Patent Application
20250146403
The present invention relates to the field of well treatment and more specifically well treatments including fracturing, acidizing, acidizing fracturing, enhanced oil recovery treatment and/or water control treatments. Aspects of the invention include a method of assessing and characterising a well treatment. Another aspect relates to the optimisation of well treatments. A further aspect relates to characterisation well treatments to improve production forecasting.
The efficient recovery of hydrocarbons from a reservoir is a difficult and complex process which requires an understanding of the flow conditions of the hydrocarbons in the reservoir, formation and connected wells.
Well stimulation techniques use mechanical or chemical methods to artificially create channels in the formation which may facilitate the flow of fluids in order to extract economically viable quantities of hydrocarbon from formations with low flow characteristics. Well stimulation techniques include fracturing, acidizing and fracture acidizing methods.
Fracturing is a method which involves pumping a large volume of fracturing liquid, typically water, from a well into a formation, causing cracks in the formation enabling the flow of fluids through the cracks to extract the hydrocarbon through the formation. The cracks are filled with a supporting material called proppant to prevent the cracks from closing during hydrocarbon production. During hydraulic fracturing, planar or complex fracture networks may form. Knowing the fracture complexity can allow for better forecasting of production and improved treatment design optimization.
Acidizing is a method of exposing minerals and rock in the formation to an acid. The minerals and rock are dissolved by the acid creating channels into the rock through which hydrocarbon can flow. During acidizing of formations typically a carbonate formation, complex flow patterns called wormholes form as a result of acid transport and reaction in the porous formation media. The wormhole structure may vary significantly. Knowing the wormhole structure created in the reservoir would allow for better forecasting of production and for optimization of the treatments.
Fracture acidizing is a well-stimulation operation in which an acid is injected into a formation typical a carbonate formation at a pressure above the formation-fracturing pressure. Flowing acid may etch the fracture faces in a nonuniform pattern, forming conductive channels which remain open without a propping agent after the fracture closes.
Differential etch patterns form on the fracture faces which enhance productivity.
The length and pattern of the etched fracture depends on acid leak-off and acid spending. The development of wormholes in the fracture face can increase the reactive surface area and cause excessive leak-off and rapid spending of the acid. Knowing the etch length and pattern created in the reservoir would allow for better forecasting of production and for optimization of the treatments.
It is amongst the aims and objects of the invention to provide a method and system for characterising changes in flow profiles following well treatments.
It is another object of an aspect of the invention to provide a method and system for assessing at least one flow path and/or characteristics of at least one flow path after a well treatment using tracer data.
It is another object of the present invention to provide a method of assessing or characterising changes in flow profiles during and/or after a well treatment operation.
It is further object of the present invention to provide a method of assessing curves from tracer residence time distribution (RTD) response to assess the type of flow pattern that are created in the reservoir as a result of well treatments such as matrix acidizing, fracture acidizing, hydraulic fracturing stimulation treatments water control treatment and/or enhanced oil recovery treatment.
Further aims and objects of the invention will become apparent from reading the following description.
According to a first aspect of the invention there is provided a method of characterising a a well treatment, the method comprising:
The well treatment may be selected from the group comprising well stimulation treatment, acidizing treatment, matrix acidizing treatment, fracturing treatment, hydraulic fracturing treatment, fracture acidizing treatment, enhanced oil recovery treatment, and/or water control treatment.
The method may comprise introducing the two or more tracers at known different times and/or stages of the well treatment. The method may comprise introducing at least one tracer into a well before and/or with the well treatment. The method may comprise introducing at least one tracer into a well at an early stage or portion of the well treatment. The method may comprise introducing a first tracer into a well before and/or with the well treatment. The may comprise introducing a second or further tracer into a well at a known time after introducing the first tracer into the well. The method may comprise introducing at least one tracer into a well at a later stage or later portion of the well treatment or after at least one well treatment stage has been completed or approaching completion. The method may comprise introducing a first tracer into a well before and/or with the well treatment and introducing at least a second tracer into a well at a later stage or later portion of the well treatment or after at least one well treatment stage has been completed or approaching completion. The method may comprise introducing a plurality of tracers into the well. The method may comprise obtaining tracer test data of the reservoir and/or well before the well treatment from historical tracer injection and/or production associated with production from the reservoir. The method may comprise obtaining tracer test data from historical tests previously conducted before the well treatment. The historical tracer data may be stored in a database.
The method may comprise introducing at least one tracer into the well by injecting the tracer into the well from surface and/or from a downhole device. The method may comprise introducing each of the two or more tracers into the well by injecting the tracer into the well from surface and/or from a downhole device. Each of the two or more tracers may be installed, arranged or positioned in the well. The method may comprise introducing the at least one tracer into the well by releasing the tracer from installed, arranged or positioned tracer source in the well. Each of the two or more tracers may be a liquid, solid or gas tracer. The two or more tracers may be a solid tracer configured to slowly release from particulates pumped with the treatment such as proppant particles or fluid loss particles. The method may comprise injecting at least one partitioning tracer with at least one passive tracer into the reservoir. The method may comprise injecting at least one reactive partitioning tracer with at least one passive tracer into the reservoir. The method may comprise injecting at least one partitioning tracer with at least one passive tracer concurrently. At least one tracer may be premixed with a well treatment fluid. At least one tracer may be added to the well treatment fluid. At least one tracer may be co-injected with a well treatment fluid. At least one tracer may be co-released with the well treatment fluid. At least one tracer may be in an inflow tracer. At least one may be in particulate form. At least one may comprise a fluid loss additive. At least one may be a proppant. Each of the two or more tracers may be distinct or different to one another. Each of the two or more tracers may be a chemical tracer. Each of the two or more tracers may be non-radioactive tracer. The method may comprise introducing at least one tracer into the well with a slurry. At least one tracer may be a component or mixed with a pre-acid slurry or composition. The method may comprise introducing at least one tracer into the well with a treatment fluid. The method may comprise introducing at least one tracer into the well with an acid fluid. The method may comprise introducing at least one tracer into the well with a fracturing fluid. The first tracer may be a component or mixed with a pre-acid slurry, treatment fluid, acid fluid, pad fluid and/or fracturing fluid.
The method may comprise calculating, estimating and/or determining at least one spatial or temporal moment for each of the two or more tracers from a measured tracer data set. The method may comprise comparing the at least one spatial or temporal moment of each of the two or more tracers. The at least one spatial or temporal moment may be at least one spatial or temporal tracer distribution moment. The method may comprise comparing at least one spatial or temporal moment for the first tracer with at least one spatial or temporal moment for the second tracer. The method may comprise measuring, calculating or determining a difference or change between the least one spatial or temporal moment for the two or more tracers. The method may comprise measuring, calculating or determining a difference or change between the least one spatial or temporal moment of the first tracer and the at least second tracer. The method may comprise associating a difference or change between the at least one spatial or temporal moment for the two of more tracers with a characteristic of the well treatment. The method may comprise associating a difference or change between the at least one spatial or temporal moment for the first tracer and the at least second tracer with a characteristic of the well treatment.
The method may comprise analysing a measured tracer data set for each of the two or more tracers. The measured tracer data set may be a tracer concentration as a function of time. The measured tracer data set may be a tracer concentration time series. The measured tracer data set may be a residence time distribution. Each of the two or more tracers may be a water tracer, an oil tracer and/or a gas tracer. The measured tracer data set may be a tracer concentration as a function of space. The measured tracer data set may be a tracer concentration measured at distinct positions in space. The measured tracer data set may be a spatial distribution of tracer. The method may comprise storing the measured tracer data sets in a database. The at least one moment may be selected from a zero order moment, a first order moment and/or a second order moment. The at least one order moment may be more than two orders.
The method may comprise calculating a residence time distribution data set for each of the two or more tracers. The method may comprise calculating a residence time distribution data set for the first tracer. The method may comprise calculating a residence time distribution data set for the second or further tracer. The method may comprise obtaining or calculating a residence time distribution by monitoring the tracer concentration produced from the reservoir as a function of time and/or space. The method may comprise creating a tracer curve from the measured tracer concentration as a function of time. The method may comprise calculating an area under the tracer curve to calculate the at least one moment of measured tracer data set. The method may comprise comparing the at least one moment of the measurement data set of the first tracer and the at least one moment of the measurement data set of the at least the second tracer to characterise and/or assess the well treatment. The method may comprise calculating a swept volume for each of the two or more tracers. The method may comprise calculating a swept volume of the first tracer in the reservoir from the first order moment of the first tracer data set. The method may comprise calculating a swept volume of the at least the second tracer in the reservoir from the first order moment of the at least the second tracer data set. The method may comprise comparing the sweep volumes from before and after the treatment.
The method may comprise comparing tracer response data following a well treatment or well treatment stage with a tracer response data conducted separately prior to the well treatment or well treatment stage. The method may comprise calculating at least one tracer arrival time characteristic. The method may comprise calculating at least one tracer arrival time characteristic for each of the two or more tracers. The method may comprise calculating tracer arrival time characteristic for the first tracer. The method may comprise calculating tracer arrival time characteristic for the second tracer. The arrival time characteristic may comprise first arrival times and/or average arrival times. The method may comprise comparing the arrival time characteristic for the two or more tracers to assess the well treatment and/or to assess a magnitude of change associated with the well treatment. The method may comprise comparing the arrival time characteristic for the first and second tracer to assess the well treatment and/or to assess a magnitude of change associated with the well treatment. The method may comprise comparing the tracer response curves of the two or more tracers to assess the well treatment.
The method may comprise comparing the at least one moment for the two or more tracers to assess the well treatment and/or to assess a magnitude of change associated with the well treatment. The method may comprise comparing the at least one moment for the first and/or second tracer to assess the well treatment and/or to assess a magnitude of change associated with the well treatment. The method may comprise analysing the measured tracer data to characterizing a reservoir flow pattern. The method may comprise analysing the measured tracer data to identify a reservoir flow pattern and/or identify a reservoir flow pattern type created by the well treatment.
The method may comprise identifying at least one characteristic including a type of stimulation pattern, flow pattern and/or fracture type. The method may comprise identifying at least one characteristic including loss in complexity and/or loss in conductivity over time. The method may comprise identifying a type of stimulation pattern, flow pattern and/or fracture types by comparing a measured tracer response curve with a library of tracer response curves associated with various stimulation pattern, flow pattern and/or fracture types. The method may comprise identifying a type of stimulation pattern, flow pattern and/or fracture type by comparing a measured tracer residence time distribution pattern with a library of residence time distribution patterns associated with various stimulation pattern, flow pattern and/or fracture types. The method may comprise identifying or characterising a degree of complexity or shape of a fracture or flow path pattern. The method may comprise identifying a type of stimulation pattern, flow pattern and/or fracture type by comparing a measured arrival time data set with a library of arrival time data sets associated with various stimulation patterns, flow patterns and/or fracture types. The method may comprise characterising and/or classifying the tracer response curve type. The method may comprise identifying a stimulation treatment status, well treatment status or pattern based on the characterised and/or classified tracer response curve type. The library of tracer response curves, residence time distribution pattern and/or arrival time data sets associated with various stimulation patterns, flow patterns and/or fracture types may be determined from model simulations, laboratory core flow experiments, laboratory fracture conductivity experiments, calibration of typical treatment results in the field and/or historical tracer injection and/or production data.
The method may comprise repeating the analysis for multiple treatment stages in a single well. For each treatment stage at least one tracer may be introduced before and/or with the well treatment. For each treatment stage at least one tracer may be introduced a later stage or later portion of the well treatment or after at least one well treatment stage has been completed or approaching completion. The method may comprise optimising the well treatment to achieve the optimum stimulation pattern, flow pattern and/or fracture type. The method may comprise optimising the well treatment to achieve the optimum stimulation pattern, flow pattern and/or fracture type in future well treatments stages. The method may comprise optimising the well treatment by adjusting one or more parameters selected from the group comprising stimulation fluid type, fluid viscosity, fluid reactivity, acid concentration, additive concentration, injection volume, injection rates, pulsing, proppant concentrations, fluid loss additive concentration and/or diverting agents. The method may comprise optimising the well treatment by adjusting additional treatment and/or changing the treatment design in subsequent stages or subsequent wells.
The method may comprise forecasting production and reservoir performance based on identified stimulation patterns, flow patterns and/or fracture types. The method may comprise adjusting production simulations and/or reservoir simulations with identified stimulation patterns, flow patterns and/or fracture types to improve or assist forecasting of production and reservoir performance. The method may comprise characterising changes in reservoir flow patterns. The method may comprise controlling or adjusting reservoir flow patterns based on the measured tracer data. The method may comprise injecting surfactants to change wettability. The method may comprise injecting diverting agents to block zones from further injection. The method may comprise injecting polymers to modify sweep profiles during enhanced oil recovery (EOR). The method may comprise injecting plugging agents for water control.
The method may comprise analysing the measured tracer data to identify a flow path type through a formation. The method may comprise analysing the measured tracer data to identify and/or characterise a flow path type created as a result of a well treatment such as matrix acidizing, fracture acidizing and/or hydraulic fracturing. The flow path type may be selected from the group comprising a face dissolution, conical wormhole, dominant wormhole, ramified wormhole, uniform dissolution, an etch pattern, a near-wellbore dissolution, heterogeneous etch channel, channels, planar fractures, complex fractures and/or cracks. The method may comprise obtaining well treatment data. The well treatment data may be selected from the group comprising treatment type, treatment fluid type, fluid reactivity, injection rate, injection volume, and/or treatment pressure. The well stimulation treatment may be selected from the group comprising acidizing, matrix acidizing, fracturing, hydraulic fracturing, and/or fracture acidizing. The method may be used to characterize the type of fracture driven interaction, commonly referred to as frac hit. The method may be used to characterize the change in flow profile created by enhanced oil recovery operations.
The method may comprise creating a model of the reservoir and/or well. The method may comprise creating a model of the well treatment. The method may comprise creating a model of the well stimulation treatment. The method may comprise constructing a model of the reservoir, well and/or well treatment from measured physical data. The method may comprise constructing the model from historical measured tracer data. The method may comprise characterizing the well treatments based on the model. The method may comprise controlling and/or adjusting well treatments based on the model. The method may comprise controlling and/or adjusting parameters of well treatments based on the model. The adjustable parameters may be selected from the group comprising treatment type, treatment fluid type, reactivity, injection volume, injection rate, pulsing and/or injection pressure. The method may comprise modelling data from each of the tracers. The model tracer data set may be a tracer concentration as a function of time. The model tracer data set may be a tracer concentration time series. The model tracer data set may be a modelled residence time distribution. The model tracer data set may be a residence time distribution. The model tracer data set may be a tracer concentration as a function of space. The model tracer data set may be a tracer concentration measured at distinct positions in space. The model tracer data set may be a modelled spatial distribution of tracer. The model tracer data set may be a spatial distribution of tracer. The method may comprise creating a tracer curve from the modelled tracer concentration as a function of time. The method may comprise calculating an area under the tracer curve to calculate the at least one moment of modelled tracer data set. The method may comprise analysing the tracer data from the two or more tracers. The method may comprise modelling data from the two or more tracers. The method may comprise iteratively varying at least one a value of at least one parameter in the model until an optimal well treatment is determined. The method may comprise comparing measured tracer data with a library of modelled and/or historical tracer data sets or response curves associated with various stimulation patterns, flow patterns and/or fracture types. The method may be a computer-implemented method. The method may comprise storing the measured tracer data to a database. The method may comprise storing the model data to a database. The method may comprise interrogating or comparing the modelled tracer data, library of tracer data and/or tracer data database with at least one measured tracer data set.
The method may comprise characterizing the well treatment based on the measured tracer data set and/or model. The method may comprise modifying the well treatment based on the measured tracer data set and/or model. The method may comprise modifying a future stage of the well treatment based on the measured tracer data set and/or model. The method may comprise modifying a future well treatment based on the measured tracer data set and/or model. The method may comprise modifying injection and/or injection rates into the well and/or reservoir based on the measured tracer data set and/or model. The method may comprise modifying production and/or production rates from the reservoir based on the measured tracer data set and/or model. The reservoir and/or well may be a hydrocarbon reservoir well, an unconventional reservoir, a reservoir undergoing enhanced oil recovery (EOR) operations, or a geothermal reservoir/well.
According to a second aspect of the invention there is provided a method of characterising or assessing a well treatment, the method comprising:
The method may comprise calculating, obtaining and/or measuring a tracer data set for at least one tracer present in the well before and/or at an early stage or portion of the well treatment. The method may comprise producing fluid in the well from the reservoir after the well treatment. The method may comprise collecting samples of produced fluid.
The method may comprise analysing the samples for the presence and/or concentration of the two or more tracers. The method may comprise assessing the well stimulation treatment based on the presence and/or concentration of the tracers in the samples assessing the well treatment. The method may comprise introducing the two or more tracers at known different times and/or stages of the well treatment. The method may comprise introducing at least one tracer into a well before and/or with the well treatment. The method may comprise introducing at least one tracer into a well at an early stage of the well treatment. The method may comprise introducing a first tracer into a well before and/or with the well treatment. The may comprise introducing a second or further tracer into a well at a known time after introducing the first tracer into the well. The method may comprise introducing at least one tracer into a well at a later stage or later portion of the well treatment or after at least one well treatment stage has been completed or approaching completion. The method may comprise introducing a first tracer into a well before and/or with the well treatment and introducing at least a second tracer into a well at a later stage or later portion of the well treatment or after at least one well treatment stage has been completed or approaching completion. The method may comprise introducing a plurality of tracers into the well.
The method may comprise calculating, estimating and/or determining at least one spatial or temporal moment for each of the two or more tracers from a measured tracer data set. The method may comprise comparing the at least one spatial or temporal moment of each of the two or more tracers. The method may comprise measuring, calculating or determining a difference or change between the least one spatial or temporal moment for the two or more tracers. The method may comprise associating a difference or change between the at least one spatial or temporal moment for the two of more tracers with a characteristic of the well stimulation treatment. The method may comprise analysing a measured tracer data set for each of the two or more tracers. The measured tracer data set may be a tracer concentration as a function of time. The measured tracer data set may be a tracer concentration time series. The method may comprise calculating a residence time distribution data set for each of the two or more tracers. The method may comprise creating a tracer curve from the measured tracer concentration as a function of time. The method may comprise calculating an area under the tracer curve to calculate the at least one moment of measured tracer data set. The method may comprise comparing the at least one moment of the measurement data set of the first tracer and the at least one moment of the measurement data set of the at least the second tracer to characterise and/or assess the well treatment. The method may comprise calculating a swept volume for each of the two or more tracers. The method may comprise calculating at least one tracer arrival time characteristic. The method may comprise calculating at least one tracer arrival time characteristic for each of the two or more tracers. The method may comprise comparing the arrival time characteristic for the two or more tracers to assess the well treatment. The method may comprise analysing the measured tracer data to characterizing a reservoir flow pattern. The method may comprise analysing the measured tracer data to identify a reservoir flow pattern. The method may comprise analysing the measured tracer data to identify a reservoir flow pattern type created by the well treatment.
The method may comprise identifying a type of stimulation pattern, flow pattern and/or fracture type by comparing a measured tracer response curve with a library of tracer response curves associated with various stimulation patterns, flow patterns and/or fracture types. The method may comprise identifying a type of stimulation pattern, flow pattern and/or fracture type by comparing a measured tracer residence time distribution pattern with a library of residence time distribution patterns associated with various stimulation patterns, flow patterns and/or fracture types. The method may comprise identifying a type of stimulation pattern, flow patterns and/or fracture type by comparing a measured arrival time data set with a library of arrival time data sets associated with various stimulation patterns, flow patterns and/or fracture types. The method may comprise characterising and/or classifying the tracer response curve type. The method may comprise identifying a stimulation treatment status, well treatment status or pattern based on the characterised and/or classified tracer response curve type. The library of tracer response curves, residence time distribution pattern and/or arrival time data sets associated with various stimulation patterns, flow patterns and/or fracture types may be determined from model simulations, laboratory core flow experiments, laboratory fracture conductivity experiments, calibration of typical treatment results in the field and/or historical tracer injection and/or production data.
Embodiments of the second aspect of the invention may include one or more features of the first aspect of the invention or its embodiments, or vice versa.
According to a third aspect of the invention there is provided a method of optimising a a well treatment, the method comprising:
The method may comprise optimising the well treatment to achieve the optimum stimulation pattern, flow pattern and/or fracture type. The method may comprise optimising the well treatment to achieve the optimum stimulation pattern, flow patterns and/or fracture type in future well treatments stages. The method may comprise optimising the well treatment by adjusting one or more parameters selected from the group comprising well treatment type, stimulation type, stimulation fluid type, fluid reactivity, injection volume, injection rates, proppant concentrations and/or diverting agents. The method may comprise optimising the well treatment by adjusting additional treatment and/or changing the treatment design in subsequent stages or subsequent wells.
The method may comprise forecasting production and reservoir performance based on identified stimulation patterns, flow pattern and/or fracture types. The method may comprise adjusting production simulations and/or reservoir simulations with identified stimulation patterns, flow pattern and/or fracture types to improve or assist forecasting of production and reservoir performance. The well treatment may be selected from the group comprising well stimulation treatment, acidizing treatment, matrix acidizing treatment, fracturing treatment, hydraulic fracturing treatment, fracture acidizing treatment, enhanced oil recovery treatment, and/or water control treatment. The method may comprise characterising changes in reservoir flow patterns. The method may comprise controlling or adjusting reservoir flow patterns based on the measured tracer data. The method may comprise injecting surfactants to change wettability. The method may comprise injecting diverting agents to block zones from further injection. The method may comprise injecting polymers to modify sweep profiles during enhanced oil recovery (EOR). The method may comprise injecting plugging agents for water control.
The method may comprise analysing the measured tracer data to identify a flow path type through a formation. The method may comprise analysing the measured tracer data to identify a flow path type created as a result of a stimulation treatment such as matrix acidizing, fracture acidizing and/or hydraulic fracturing. The flow path type may be selected from the group comprising a face dissolution, conical wormhole, dominant wormhole, ramified wormhole, uniform dissolution, an etch pattern, a near-wellbore dissolution, heterogeneous etch channel, channels, planar fractures, complex fractures and/or cracks.
The method may comprise obtaining well stimulation treatment data. The well stimulation treatment data may be selected from the group comprising treatment fluid type, fluid reactivity, injection rate, injection volume, and/or treating pressure. The well stimulation treatment may be selected from the group comprising acidizing, matrix acidizing, fracturing, hydraulic fracturing, and/or fracture acidizing.
The method may comprise creating a model of the reservoir and/or well. The method may comprise controlling and/or adjusting well stimulation treatments based on the model. The method may comprise controlling and/or adjusting parameters of well stimulation treatments based on the model. The adjustable parameters may be selected from the group comprising treatment type, treatment fluid type, reactivity, injection volume, injection rate and/or injection pressure. The method may comprise controlling the stimulation treatment based on the measured tracer data set and/or model. The method may comprise controlling a future stage of stimulation treatment based on the measured tracer data set and/or model. The method may comprise controlling a future stimulation treatment based on the measured tracer data set and/or model. The method may comprise controlling injection and/or injection rates into the well and/or reservoir based on the measured tracer data set and/or model. The method may comprise controlling production and/or production rates from the reservoir based on the measured tracer data set and/or model.
Embodiments of the third aspect of the invention may include one or more features of the first or second aspects of the invention or their embodiments, or vice versa.
According to a fourth aspect of the invention there is provided a method of characterising a a hydraulic fracturing treatment, the method comprising:
The method may comprise analysing the measured tracer data to identify a flow path type through a formation. The method may comprise analysing the measured tracer data to identify a flow path type created as a result of a hydraulic fracturing treatment. The method may comprise identifying a flow path type selected from the group comprising channels, planar fractures, complex fractures and/or cracks. The method may comprise characterizing a loss in conductivity from a hydraulic fracture over time. At least one tracer may be a solid tracer. At least one tracer may be a slow release tracer. At least one tracer may be located or positioned into the near-wellbore region. At least one tracer may be an inflow tracer placed in the completion or a particulate tracer in the near wellbore. At least one tracer may be located or positioned into a fracture network. The method may comprise exposing the two or more tracers to the same flow rate from the same fracture. The method may comprise assessing a difference in tracer response from the two or more tracers to characterize a loss in conductivity over time.
Embodiments of the fourth aspect of the invention may include one or more features of any of the first to third aspects of the invention or their embodiments, or vice versa.
According to a fifth aspect of the invention there is provided a method of characterising a well stimulation acidizing treatment, the method comprising:
The method may comprise introducing at least one tracer into a well before and/or with the well stimulation treatment. The method may comprise introducing the two or more tracers at known different times and/or stages of the well stimulation treatment. The method may comprise introducing at least one tracer into a well at an early stage of the well stimulation treatment. The method may comprise introducing a first tracer into a well before and/or with the well stimulation treatment. The method may comprise introducing a second or further tracer into a well at a known time after introducing the first tracer into the well. The method may comprise introducing at least one tracer into a well at a later stage or later portion of the well stimulation treatment or after at least one well stimulation treatment stage has been completed or approaching completion. The method may comprise introducing a first tracer into a well before and/or with the well stimulation treatment and introducing at least a second tracer into a well at a later stage or later portion of the well stimulation treatment or after at least one well stimulation treatment stage has been completed or approaching completion. The method may comprise introducing a plurality of tracers into the well.
The method may comprise analysing the measured tracer data to identify a flow path type through a formation. The method may comprise analysing the measured tracer data to identify a flow path type created as a result of the acidizing treatment. The method may comprise identifying a flow path type selected from the group comprising face dissolution, conical wormhole, dominant wormhole, ramified wormhole, uniform dissolution, an etch pattern, a near-wellbore dissolution and/or heterogeneous etch channel, depth of perforation, channel size and type, planar fractures, complex fractures and/or cracks.
Embodiments of the fifth aspect of the invention may include one or more features of any of the first to fourth aspects of the invention or their embodiments, or vice versa.
According to a sixth aspect of the invention there is provided a method of characterising a an acidizing fracturing treatment, the method comprising:
The method may comprise introducing at least one tracer into a well before and/or with the well stimulation treatment. The method may comprise introducing the two or more tracers at known different times and/or stages of the well stimulation treatment. The method may comprise introducing at least one tracer into a well at an early stage of the well stimulation treatment. The method may comprise introducing a first tracer into a well before and/or with the well stimulation treatment. The method may comprise introducing a second or further tracer into a well at a known time after introducing the first tracer into the well. The method may comprise introducing at least one tracer into a well at a later stage or later portion of the well stimulation treatment or after at least one well stimulation treatment stage has been completed or approaching completion. The method may comprise introducing a first tracer into a well before and/or with the well stimulation treatment and introducing at least a second tracer into a well at a later stage or later portion of the well stimulation treatment or after at least one well stimulation treatment stage has been completed or approaching completion. The method may comprise introducing a plurality of tracers into the well.
The method may comprise analysing the measured tracer data to identify a flow path type through a formation. The method may comprise analysing the measured tracer data to identify a flow path type created as a result of the acidizing fracturing treatment. The method may comprise identifying a flow path type selected from the group comprising face dissolution, conical wormhole, dominant wormhole, ramified wormhole, uniform dissolution, an etch pattern, a near-wellbore dissolution and/or heterogeneous etch channel, depth of perforation, channel size and type, planar fractures, complex fractures and/or cracks.
Embodiments of the sixth aspect of the invention may include one or more features of any of the first to fifth aspects of the invention or their embodiments, or vice versa.
According to a seventh aspect of the invention, there is provided a method of characterising a well stimulation treatment, the method comprising:
The samples previously may be collected from the production flow after introducing a first tracer into the well into the well before and/or with a well stimulation treatment; and introducing at least a second tracer at a later stage of the well stimulation treatment or after the well stimulation treatment has been completed.
Embodiments of the seventh aspect of the invention may include one or more features of any of the first to sixth aspects of the invention or their embodiments, or vice versa.
According to an eighth aspect of the invention, there is provided a method of optimising a well stimulation treatment, the method comprising:
The samples may be previously collected from the production flow after introducing a first tracer into the well into the well before and/or with a well stimulation treatment; and introducing at least a second tracer at a later stage of the well stimulation treatment or after the well stimulation treatment has been completed. The method may comprise optimising the well stimulation treatment to achieve the optimum stimulation pattern and/or fracture type. The method may comprise optimising the well stimulation treatment to achieve the optimum stimulation pattern and/or fracture type in future well stimulation treatments stages. The method may comprise optimising the well stimulation treatment by adjusting one or more parameters selected from the group comprising stimulation fluid type, fluid viscosity, fluid reactivity, acid concentration, additive concentration, injection volume, injection rates, pulsing, proppant concentrations, fluid loss additive concentration and/or diverting agents. The method may comprise optimising the well stimulation treatment by adjusting additional treatment and/or changing the treatment design in subsequent stages or subsequent wells.
The method may comprise forecasting production and reservoir performance based on identified stimulation patterns, flow patterns and/or fracture types. The method may comprise adjusting production simulations and/or reservoir simulations with identified stimulation patterns and/or fracture types to improve or assist forecasting of production and reservoir performance.
The method may comprise characterising changes in reservoir flow patterns. The method may comprise modifying or adjusting reservoir flow patterns based on the measured tracer data. The method may comprise injecting surfactants to change wettability. The method may comprise injecting diverting agents to block zones from further injection. The method may comprise injecting polymers to modify sweep profiles during enhanced oil recovery (EOR). The method may comprise injecting plugging agents for water control. The method may comprise analysing the measured tracer data to identify a flow path type through a formation. The method may comprise analysing the measured tracer data to identify a flow path type created as a result of a stimulation treatment such as matrix acidizing, fracture acidizing and/or hydraulic fracturing. The flow path type may be selected from the group comprising a face dissolution, conical wormhole, dominant wormhole, ramified wormhole, uniform dissolution, an etch pattern, a near-wellbore dissolution, heterogeneous etch channel, channels, planar fractures, complex fractures and/or cracks.
The method may comprise obtaining well stimulation treatment data. The well stimulation treatment data may be selected from the group comprising treatment fluid type, fluid reactivity, injection rate, injection volume, and/or treating pressure. The well stimulation treatment may be selected from the group comprising acidizing, matrix acidizing, fracturing, hydraulic fracturing, frac hit, enhanced oil recovery and/or fracture acidizing.
The method may comprise creating a model of the reservoir and/or well. The method may comprise creating a model of the well stimulation treatment. The method may comprise constructing a model of the reservoir, well and/or well stimulation treatment from measured physical data. The method may comprise constructing the model from historical measured tracer data. The method may comprise characterizing the well stimulation treatments based on the model. The method may comprise creating a tracer curve from the modelled tracer concentration as a function of time. The method may comprise calculating an area under the tracer curve to calculate the at least one moment of modelled tracer data set.
The method may comprise controlling and/or adjusting well stimulation treatments based on the model. The method may comprise controlling and/or adjusting parameters of well stimulation treatments based on the model. The adjustable parameters may be selected from the group comprising treatment type, treatment fluid type, reactivity, injection volume, injection rate and/or injection pressure.
The method may comprise characterizing the stimulation treatment based on the measured tracer data set and/or model. The method may comprise controlling the stimulation treatment based on the measured tracer data set and/or model. The method may comprise controlling a future stage of stimulation treatment based on the measured tracer data set and/or model. The method may comprise controlling a future stimulation treatment based on the measured tracer data set and/or model. The method may comprise controlling injection and/or injection rates into the well and/or reservoir based on the measured tracer data set and/or model. The method may comprise controlling production and/or production rates from the reservoir based on the measured tracer data set and/or model.
The reservoir and/or well may be a hydrocarbon reservoir well, an unconventional reservoir; a geothermal reservoir/well.
Embodiments of the eighth aspect of the invention may include one or more features of any of the first to seventh aspects of the invention or their embodiments, or vice versa.
According to a ninth aspect of the invention there is provided an interpretation method for a treatment of a well comprising;
The known times of the well treatment may be before, during and/or after the well treatment. The method may comprise analysing the tracer data to estimate at least one characteristic of the well after the treatment based on the presence and/or concentration of tracers in the samples. The method may comprise introducing at least one tracer before or at an early stage or portion of the well treatment. The well treatment may be selected from the group comprising well stimulation treatment, acidizing treatment, matrix acidizing treatment, fracturing treatment, hydraulic fracturing treatment, fracture acidizing treatment, enhanced oil recovery treatment, and/or water control treatment.
Embodiments of the ninth aspect of the invention may include one or more features of any of the first to eighth aspects of the invention or their embodiments, or vice versa.
According to a tenth aspect of the invention there is provided a computer-readable medium, comprising statements, instructions and/or code configured to direct at least one processor to compare at least a first tracer data set and a second tracer data set;
wherein the first tracer data set is obtained from a first tracer introduced into the well before a well treatment, with a well treatment and/or at an early stage or portion of the well treatment and measured first tracer concentrations as a function of time in produced fluids;
The at least one processor may be configured to calculate and/or analyse an arrival time of the first tracer data set. The at least one processor may be configured to calculate and/or analyse an arrival time of the second or further tracer data set. The at least one processor may be configured to calculate and/or analyse a residence time distribution of the first tracer data set. The at least one processor may be configured to calculate and/or analyse a residence time distribution of the second or further tracer data set. The at least one processor may be configured to calculate at least one moment of the first tracer data set. The at least one processor may be configured to calculate at least one moment of the second tracer data set. The at least one processor may be configured to determine a comparison value of the at least one moment of the first tracer data set compared to the at least one moment of the second tracer data set. The method may comprise calculating at least one moment of the residence time distribution data from the first tracer data set. The method may comprise calculating at least one moment of the residence time distribution data from the second tracer data set. The at least one processor may be configured to compare the tracer response curves of the two or more tracers to assess the well stimulation treatment. The at least one processor may be configured to compare measured tracer response curves with a library of tracer response curves associated with various stimulation pattern and/or fracture types. The at least one processor may be configured identifying a type of stimulation patterns and/or fracture types by comparing a measured tracer residence time distribution pattern with a library of residence time distribution patterns associated with various stimulation pattern and/or fracture types.
Embodiments of the tenth aspect of the invention may include one or more of any of features of the first to ninth aspects of the invention or their embodiments, or vice versa.
According to an eleventh aspect of the invention there is provided a system for characterising and/or optimising a well stimulation treatment, the systems comprises:
The at least one tracer release mechanism may be configured to be located in the well. The at least one tracer release mechanism may be configured to be located downhole. The at least one tracer release mechanism may be configured to be located at surface. The at least one tracer release mechanism may be configured to release tracer into the well. The released tracer may be carried with a well stimulation fluid or displacement fluid into the formation and/or reservoir. The at least one tracer release mechanism may be configured to pump or inject tracer into the well. The system may comprise two or more tracer release mechanism. The system may comprise a tracer release mechanism for each tracer. The at least one tracer release mechanism may be configured to release, pump or inject tracer on command and/or a pre-programmed timer or sequence. The at least one tracer release mechanism may be configured introduce the two or more tracer into a well at known times and/or stages of the well stimulation treatment.
The at least one sampling device may be configured to collect or take samples of the production flow. The at least one sampling device may be configured to collect or take samples at one or more sampling times. The at least one sampling device may be configured to collect or take samples of well fluid at the surface or downhole. The at least one sampling device may be configured to collect or take samples for further analysis onsite or offsite. The at least one sampling device may be configured to detect the presence of one or more tracers. The at least one sampling device may be configured to detect the presence of tracer one or more tracers in real time. The sampling device may be configured to measure the concentration of one or more tracers in the well fluid. The sampling device may be configured to measure the concentration of one or more tracers in the well fluid in real time.
The system may comprise a tracer analyser. The system may comprise at least one processor. The at least one processor may be a computer processor. The at least one processor may be configured to analyse and/or compare tracer data sets of the two or more tracers in collected samples.
Embodiments of the eleventh aspect of the invention may include one or more of any of features of the first to tenth aspects of the invention or their embodiments, or vice versa.
According to a twelfth aspect of the invention there is provided a method of characterising a well treatment, the method comprising:
The well treatment may be selected from the group comprising well stimulation treatment, acidizing treatment, matrix acidizing treatment, fracturing treatment, hydraulic fracturing treatment, fracture acidizing treatment, enhanced oil recovery treatment, and/or water control treatment.
The at least one tracer in the well before the well treatment and/or in an early portion of the well treatment is preferably distinct from the at least one tracer introduced into the well at a later stage or later portion of the well treatment or after at least well treatment stage has been completed or approaching completion. The method may comprise calculating, estimating and/or determining at least one spatial or temporal tracer distribution moment for each distinct tracer introduced or present in the well before, during and/or after each stage or portion of a well treatment. The method may comprise introducing at least one tracer into a well before and/or with the well treatment. The method may comprise calculating, estimating and/or determining at least one spatial or temporal tracer distribution moment for at least one tracer in the well before the well treatment from historical tracer injection and/or production associated with production from the reservoir. The method may comprise introducing each of the two or more tracers into the well by injecting the two or more tracers into the well from surface or from a downhole device. The method may comprise introducing at least one tracer into the well by releasing tracer from tracer sources installed, arranged or positioned in the well. The method may comprise introducing two or more tracer into the same injector well or different injector wells. The method may comprise introducing two or more tracers into an injector well, a production well or a combination of at least one injector well and production well. The method may comprise associating a difference or change between the at least one spatial or temporal tracer distribution moment for the two of more tracers with a characteristic of the well treatment. The at least one moment may be selected from a zero order moment, a first order moment, a second order moment, and/or a higher order moment.
The method may comprise analysing a measured tracer concentration data set for each of the two or more tracers. The measured tracer concentration data set is tracer concentration as a function of time, tracer concentration as a function of space and/or a residence time distribution. The method may comprise creating a tracer curve from the measured tracer concentration as a function of time and comparing the tracer curves of the two or more tracers to assess the well treatment. The method may comprise calculating an area under the tracer curve to calculate the at least one moment of measured tracer data set and comparing the area under the tracer curve for each of the two or more tracers.
The method may comprise calculating a swept volume for each of the two or more tracers and comparing the swept volume of each of the two or more tracers. The method may comprise calculating an arrival time characteristic for each of the two or more tracers and comparing the arrival time characteristic for the two or more tracers to assess a magnitude of change associated with the well stimulation treatment. The method may comprise analysing the measured tracer concentration data to characterise and/or identify a flow type pattern selected from the group comprising a face dissolution, conical wormhole, dominant wormhole, ramified wormhole, uniform dissolution, an etch pattern, a near-wellbore dissolution, heterogeneous etch channel, channels, planar fractures, complex fractures and/or cracks. The method may comprise identifying and/or characterising flow patterns by comparing a measured tracer response curve with a library of tracer response curves associated with various flow type patterns. The method may comprise improving production forecasting based on characterising flow patterns after the well treatment.
The tracers may be selected from the group comprising water tracers, oil tracers, gas tracers, or tracers deployed as solids such as in a polymer matrix, impregnated proppant, or fluid loss material. The tracer may be immobilized within and/or to a tracer release apparatus. The tracer release apparatus may comprise tracer molecules and a carrier. The carrier may be a matrix material. The matrix material may be a polymeric material.
The tracer material may be chemically immobilized in a way that it releases tracer molecules or particles in the presence of a chemical trigger. The tracer may be selected from the group comprising chemical, fluorescent, phosphorescent, metallic complex, particles, nano particles, quantum dots, magnetic, poly functionalized PEG and PPGs, DNA, antibodies and/or radioactive compounds. The tracer may comprise chemical tracers selected from the group comprising perfluorinated hydrocarbons or perfluoroethers. The perfluorinated hydrocarbons may be selected from the group of perfluoro buthane (PB), perfluoro methyl cyclopentane (PMCP), perfluoro methyl cyclohexane (PMCH).
The method may comprise introducing at least one distinctive tracer into a well before and/or with a further well treatment and introducing a different tracer into the well at a later stage or later portion of the well treatment or after at least well treatment stage has been completed or approaching completion and comparing the at least one spatial or temporal moment of the tracers to estimate at least one characteristic of the further well treatment.
Embodiments of the twelfth aspect of the invention may include one or more of any of features of the first to eleventh aspects of the invention or their embodiments, or vice versa.
According to a thirteenth aspect of the invention there is provided a method of optimising a well treatment, the method comprising:
The method may comprise optimising the well treatment by adjusting one or more parameters selected from the group comprising stimulation fluid type, fluid viscosity, fluid reactivity, acid concentration, additive concentration, injection volume, injection rates, pulsing, proppant concentrations, fluid loss additive concentration and/or diverting agents.
The method may comprise characterising changes in reservoir flow patterns and optimising the well treatment by adjusting additional treatment and/or changing the treatment design in subsequent stages or subsequent wells.
Embodiments of the thirteenth aspect of the invention may include one or more of any of features of the first to twelfth aspects of the invention or their embodiments, or vice versa.
According to a fourteenth aspect of the invention there is provided an interpretation method for a well treatment of a well comprising;
Embodiments of the fourteenth aspect of the invention may include one or more of any of features of the first to thirteenth aspects of the invention or their embodiments, or vice versa.
According to a fifteenth aspect of the invention there is provided an interpretation method for a well treatment of a well comprising;
The known times including before, during and/or after the well stimulation treatment.
Embodiments of the fifteenth aspect of the invention may include one or more of any of features of the first to fourteenth aspects of the invention or their embodiments, or vice versa.
According to a sixteenth aspect of the invention there is provided an interpretation method for a well treatment of a well comprising;
The two or more tracers may be injected in the same injector well. The two or more tracers may be injected in the different injector wells. The tracers may arrive at the production well at two or more times after the stimulation treatment.
Embodiments of the sixteenth aspect of the invention may include one or more of any of features of the first to fifteenth aspects of the invention or their embodiments, or vice versa.
There will now be described, by way of example only, various embodiments of the invention with reference to the following drawings (like reference numerals referring to like features) in which:
Well stimulation techniques use mechanical or chemical methods to artificially create channels or flow paths through the formation matrix which may facilitate the flow of fluids from a reservoir to a well. Well stimulation techniques include fracturing, acidizing and fracture acidizing methods. During matrix acidizing of a carbonate formation complex flow patterns called wormholes, form as a result of transport and reaction in the porous media. The wormhole structure depends on parameters such as the acid type, injection rate, and temperature and include face dissolution, conical wormholes, dominant wormholes, ramified wormhole, and uniform dissolution.
Analysis may also provide information on the inflow profile in the producer well.
Residence Time Distribution (RTD) is the distribution of times used by a population of tracer particles to travel through a medium. The tracers represent elements of fluid that travel through different paths, and that therefore use different amounts of time to pass through a medium. Interpretation of tracer data by use of residence time distribution (RTD) analysis may also be used to quantify sweep volume and the magnitude of connections in oil and gas reservoirs. The zero-order temporal moment of the residence time distributions (m0=∫(t)dt) give the fraction of fluid produced from the well. The first order moment m1=∫t·E(t)dt is closely related to average residence time (<t>=m1/m0).
In
In
In
In
As shown in
In an example shown in
Additionally, or alternatively a similar approach can be used to characterize other changes in reservoir flow patterns such as those that occur due to injection of surfactants to change wettability, injection of diverting agents to block zones from further injection, injection of polymers to modify sweep profiles during enhanced oil recovery (EOR) or plugging agents for water control. The injection or release of different tracers before and after the induced reservoir change and analysis of the tracer response data would be applied to provide flow profile change type curves. Additionally or alternatively tracer arrival time data may be used, such as the difference in first arrival times for tracer 2 and/or tracer 1 responses to assess and/or optimise a stimulation operation.
The etch pattern can be optimized by controlling and changing the treatment design. The etch pattern can be further impacted by viscous fingering associated with alternating stages of different treatment fluids with different viscosities. The etch patterns on the fracture face 340 can be characterized as near-wellbore dissolution as shown in
In hydraulic fracturing with fracturing fluids such as slickwater or polymer the channels which form may be planar fractures 410 having primary fractures 412 shown as
In
In
From the measured tracer data calculations a graph 700 showing a ratio of skewness between the Tracer 2 and Tracer 1 responses may be plotted versus the difference in variance between the Tracer 2 and Tracer 1 responses as shown in
Once the stimulation operation (or stages) is completed, production is induced and samples of the produced fluid are collected at step 522 at known times at a known sampling location. At step 524 the samples are analysed. In this example the analysis step includes measuring the type and tracer concentration in the samples. The analysis step may include a tracer residence time distribution analysis, measuring the arrival time of each tracer and the sampling time, calculating an average travel time to the sample location and/or swept volume of the tracer. The analysis may comprise comparing the tracer response for the first tracer with the second and optionally subsequent tracers. The first tracer response may be considered a baseline response before the stimulation treatment affects or changes the flow pattern though the matrix. The first and second tracer response are compared to identify flow path pattern and characterise the stimulation treatment for each of the stages at step 526. The characterised stimulation treatment may be used to optimise future stimulation treatments at step 528.
Optionally as shown in dotted box 570, a library of tracer response signatures for each stimulation treatment and the possible range of flow patterns and/or flow channels may be created as shown in step 530. The library may comprise tracer response signatures corresponding to a range of flow path types created as a result of various stimulation treatments such as matrix acidizing, fracture acidizing and/or hydraulic fracturing. The flow path type may include face dissolution, conical wormhole, dominant wormhole, ramified wormhole, uniform dissolution, an etch pattern, a near-wellbore dissolution, heterogeneous etch channel, channels, planar fractures, complex fractures and/or cracks.
At step 532 the measured tracer data may be compared with the library of simulation treatment responses to identify and/or characterise the stimulation treatment and flow path pattern. If the measured tracer data does not match a signature in the library, the library may be tuned or iteratively adjusted at step 540 until the modelled tracer data substantially matches the measured tracer data to within a desired target range. At step 536 based on the characterised stimulation treatment and/or flow path pattern the parameters of subsequent stimulation treatment stages or stimulation treatments may be optimised to achieve an optimum stimulation pattern and/or fracture type to improve depth penetration or conductivity. The method may comprise optimising the well stimulation treatment by adjusting one or more parameters selected from the group comprising stimulation fluid type, fluid viscosity, reactivity, acid concentration, additive concentration, injection volume, injection rates, pulsing, proppant concentrations, fluid loss additive concentration and/or diverting agents.
Optionally a model of the well and reservoir may be created or updated at step 550 with the stimulation treatment data to facilitate improved knowledge and/or control of production and reservoir performance. The model may be based on data selected from the group comprising: seismic data, geological data, reservoir geometry, core data, log data, rock mechanics, temperature, pressure, gravity, density, viscosity; reservoir permeability, reservoir heterogeneities, solubility, fluid chemistry; porosity, fluid saturation. The model may be updated with reservoir and/or pathways of injected tracer, modelled migration pathways, modelled tracer injection tracer amounts, volumes and injection rates, injection locations, sampling locations, tracer arrival time, residence time distribution, physical behaviour of tracer, stimulation type, stimulation fluid; channel type, wormhole type and/or fracture type.
The analysis of tracers in the collected samples may be a separate method to the collection of samples. Samples may be analysed at a time or jurisdiction which is separate and distinct from the sampling location and the collection of the samples. The analysis of measured tracer data may be a separate method to the collection or analysis of the samples. The tracer data may be analysed at a time or jurisdiction which is separate and distinct from the sampling location, collection of the samples and or measurement of tracer concentrations.
In the above example the first tracer and the second tracer are injected, it will be appreciated that in other examples the tracers may be released into the wellbore via alternative mechanisms such as a tracer release apparatus. The above examples describe well stimulation treatments including acidizing and fracturing treatments. It will be appreciated that the methods may be used to characterise and optimise other types of well treatment including enhanced oil recovery treatment, and/or water control treatment.
An embodiment of the invention may comprise pumping a well treatment such as a well stimulation treatment in a production well with no tracers in the treatment and analysis can be made based on tracers injected from an injection well and monitored in a production well. The first tracer (tracer 1) analysis may be based on residence time distribution measured from tracer response prior to the stimulation treatment and a second tracer (tracer 2) analysis would be based on residence time distribution measured from tracer response after the stimulation treatment, with both based on measurement from the production well that is stimulated. An embodiment of the invention may be used to characterize loss in conductivity that may occur during production from a hydraulic fracture over time. The method may comprise slow release tracer as tracer n (where n is 2 or higher) that is placed out into the fracture network and tracer 1 would be a slow release tracer placed in the near-wellbore region (such as an inflow tracer placed in the completion or a particulate tracer in the near wellbore). The method may comprise exposing both tracers to the same flow rate from the same fracture, the difference in tracer response for tracer n and tracer 1 characterizes the loss in conductivity that occurs over time.
The invention may provide methods of characterising and/or optimising a well stimulation treatment. The method may comprise introducing two or more tracers into a well at known times and/or stages of the well stimulation treatment. The method comprises producing fluid in the well from a reservoir, collecting samples of produced fluid and analysing the samples for the presence and/or concentration of the two or more tracers. Based on the presence and/or concentration of tracers in the samples estimating characteristics of the well stimulation treatment.
Embodiments of the invention may use tracer data including tracer curves from tracer residence time distribution flow back responses to facilitate the assessment and characterization of the type of flow pattern created in the reservoir as a result of well treatment including matrix acidizing, fracture acidizing, hydraulic fracturing, water control treatment and/or enhanced oil recovery treatments. By injecting two or more tracers in a treatment with at least a first tracer being injected before or at the start of a treatment before the flow profile has been significantly changed by the treatment and a second tracer injected at a later stage after the treatment has changed the flow profile, the change in the flow profile can be characterized.
Embodiments of the invention may be used to characterize other changes in reservoir flow patterns such as those that occur due to injection of surfactants to change wettability, injection of diverting agents to block zones from further injection, injection of polymers to modify sweep profiles during enhanced oil recovery (EOR), or plugging agents for water control. By injecting different tracers before and after the induced reservoir change and analysing the produced tracer data, changes in a flow profile may be characterized.
Throughout the specification, unless the context demands otherwise, the terms ‘comprise’ or ‘include’, or variations such as ‘comprises’ or ‘comprising’, ‘includes’ or ‘including’ will be understood to imply the inclusion of a stated integer or group of integers, but not the exclusion of any other integer or group of integers. Furthermore, relative terms such as “up”, “down”, “top”, “bottom”, “upper”, “lower”, “upward”, “downward”, “horizontal”, “vertical”, “and the like are used herein to indicate directions and locations as they apply to the appended drawings and will not be construed as limiting the invention and features thereof to particular arrangements or orientations.
The foregoing description of the invention has been presented for the purposes of illustration and description and is not intended to be exhaustive or to limit the invention to the precise form disclosed. The described embodiments were chosen and described in order to best explain the principles of the invention and its practical application to thereby enable others skilled in the art to best utilise the invention in various embodiments and with various modifications as are suited to the particular use contemplated. Therefore, further modifications or improvements may be incorporated without departing from the scope of the invention as defined by the appended claims.
