Patent Application
20170082551
The statements in this section merely provide background to facilitate a better understanding of the various aspects of the disclosure and may not constitute prior art. It should be understood that the statements in this section of this document are to be read in this light.
Water sourced from one or more sources, can be a component used in many oil and gas field operations. Water may be transported to the oilfield site for various purposes, including drilling mud, formation fracturing, acidizing, enhanced oil recovery including steam injection, and the like. In addition to the desired hydrocarbons, many oil and natural gas producing wells also generate large quantities of waste water, commonly referred to as “produced water.” Produced water may, in some cases, include chemicals and other substances requiring that the produced water be analyzed and/or treated before being reused or discharged to the environment. In some instances, the components may include drilling mud, or “fracturing flow back water” that may contain spent fracturing fluids including polymers and inorganic cross-linking agents, friction reducers, and the like.
Economic factors connected with transporting uncontaminated water to the well site and the typically abundant supply of produced water generated on site, it is often desirable to reuse the produced water in production operations at the well site. For example, produced water can be typically used in production stimulation treatment, which involves in one method fracturing the formation utilizing a viscous treating fluid, typically a fracturing gel, wherein the subterranean formation or producing zone is hydraulically fractured and whereby one or more cracks or “fractures” are produced. In such a method, the produced water may be used as fracturing feed water. A fracturing gel is created by combining the feed water with a polymer, such as guar gum, and in some applications a cross-linker, typically borate-based or zirconium-based, to form a fluid that gels, or increases in viscosity, at desired points during the stimulation treatment. Several additives maybe added to form a treatment fluid specifically designed for the anticipated wellbore, reservoir and operating conditions.
Contaminant species laden in the source water, as well as different quality of water from different sources, often requires the source to be analyzed to determine the species and other impurities present. The types and concentrations of the species or other impurities may typically influence the treatment to be applied and/or additives mixed to the source water to create a stimulation fluid having the specific properties required to properly treat the intended formation. In a conventional process, a sample of the source water is subject to laboratory analysis and subsequently a stimulation fluid formulation is created based on the analysis of the source water sample. Generally, personnel specifically trained to operate the extensive laboratory equipment must be employed to accurately analyze the production water sample. Additionally, such laboratory equipment typically requires extensive technical support, sufficient infrastructure, transportation means when used on site, and sufficient space to operate. Such space may be unavailable, particularly on wellsite facilities, where additional space requires substantial economic investment in the platform, drilling pad or rig. Furthermore, additional manpower required to operate the laboratory equipment offshore can result in higher operating costs for the operator of the well. Thus, the water sample is typically analyzed in a laboratory setting offsite.
Another problem associated with the submission of source water samples for analysis, particularly to an offsite laboratory, is the length of time required to obtain verification of the sample composition. Such lengths of time cause a significant delay in oil/gas production while waiting for a source water sample to arrive at the laboratory, and for the laboratory to process the sample. Inductively Coupled Plasma Mass Spectrometry (ICP-MS) instrumentation and wet chemistry techniques are commonly used, and ICP-MS requires the sample to be shipped to an offsite laboratory. Wet chemistry techniques require significant glassware, a well ventilated environment and fume-hood, and pose health and safety risks in the field. Wet chemistry techniques most often require numerous manipulations of fluids and glassware and need a trained operator to determine fluid properties (chemical or physical) in a precise and accurate manner.
Therefore, the need exists for methods that can reduce or eliminate operator errors, the number of offsite laboratory experiments needed to analyze source water, as well as techniques which enable real-time QA/QC of stimulation fluids, so that the treatment may be adjusted if needed. Techniques which achieve the above would be highly desirable, and these needs are met at least in part by the following disclosure.
This section provides a general summary of the disclosure, and is not a necessarily a comprehensive disclosure of its full scope or all of its features.
In a first aspect of the disclosure, a method includes providing a water sample for analysis, where the water sample is collected from at least one water source and the water sample includes at least one analyte. The water sample and a reagent are introduced into a microfluidic mixing cell to produce a mixture of the reagent and water sample, and the mixture has a detectable characteristic indicative of concentration of the at least one analyate in the water sample. The detectable characteristic is measured by spectrophotometry to determine concentration of the at least one analyte. Then a subterranean formation treatment fluid is prepared using water from the at least one water source based on the concentration of the at least one analyte. The introducing into the microfluidic mixing cell and the measuring by spectrophotometry are conducted over an elapsed time period of about 5 minutes or less in some cases, or even over an elapsed time period of about 1 minutes or less. In some aspects, the mixture of the reagent and water sample is passed through an optical cell concurrent with the measuring the detectable characteristic by spectrophotometry. The specific location of carrying out methods according to the disclosure may be a well site, a location proximate the well site, a laboratory (mobile, stationary, or otherwise located), or any location suitable or practical for achieving the sample analysis. However, the specific location is non-limiting to embodiments of the disclosure.
In some further embodiments, the method is repeated as many times as appropriate, or even carried out on multiple mixing/measuring arrangements. As many arrangements as deemed appropriate may be used. To illustrate, the water sample and an Nth reagent may be introduced into a Nth microfluidic mixing cell to produce a mixture of the Nth reagent and water sample, the mixture having Nth detectable characteristic indicative of concentration of a Nth analyte in the water sample. The Nth detectable characteristic may be measured by spectrophotometry to determine the concentration of the Nth analyte, and a subterranean formation treatment fluid, containing water from the at least one water source, is prepared based on the concentration of the at least one analyte and the Nth analyte. The introducing into the microfluidic mixing cells and the measuring are conducted over an elapsed time period of about 5 minutes or less, or even over an elapsed time period of about 1 minutes or less.
The methodology may further include introducing the water sample into a rotating valve, passing the water sample through a sample loading loop fluidly connected with the rotating valve, and then passing the water sample and a reagent into the microfluidic mixing cell, where the elapsed time period between the introducing the water sample into the rotating valve and the measuring is about 5 minutes or less, or even about 1 minutes or less. In some cases, a carrier fluid pushes the water sample in the rotating valve and the sample loading loop prior to the introduction the water sample into the microfluidic mixing cell. In another aspect, the carrier fluid and the reagent are introduced into the microfluidic mixing cell to produce a mixture of the reagent and the carrier fluid, the mixture of the reagent and the carrier fluid measured by spectrophotometry to determine a baseline before measuring the water sample, and the mixture of the reagent and the carrier fluid is substantially free of the water sample. The introduction of carrier fluid and reagent into the microfluidic mixing cell as well as the measurement of the mixture may be conducted separate from the introducing the water sample and the reagent into the microfluidic mixing cell and the measuring the detectable characteristic. The measured baseline and the measured detectable characteristic may be compared to determine concentration of the at least one analyte.
In another aspect of the disclosure, methods include providing at least one water source, the at least one water source containing at least one analyte, then delivering an aqueous stream from the at least one water source to a mixer and to a microfluidic mixing cell, simultaneously or in any order. A water sample from the at least one water source and a reagent are introduced into a microfluidic mixing cell to produce a mixture of the reagent and water sample, and the mixture has a detectable characteristic indicative of concentration of the at least one analyate in the water sample. The detectable characteristic is measured by spectrophotometry to determine concentration of the at least one analyte, and one or more additive components are mixed in the mixer with the aqueous stream, in amounts based on the concentration of the at least one analyte measured. A treatment fluid is prepared afterward, which contains the at least one water source and the one or more additive components, and then injected into a wellbore penetrating a subterranean formation. The introducing into the microfluidic mixing cell and the measuring by spectrophotometry are conducted over an elapsed time period of about 5 minutes or less in some cases, or even over an elapsed time period of about 1 minutes or less. In some aspects, the mixture of the reagent and water sample is passed through an optical cell concurrent with the measuring the detectable characteristic by spectrophotometry.
Yet another aspect of the disclosure provides methods of preparing a subterranean formation treatment fluid by delivering an aqueous stream from at least one water source to a mixer, providing a water sample having at least one analyate from the at least one water source, and introducing the water sample and a reagent into a microfluidic mixing cell to produce a mixture of the reagent and water sample. The mixture has a detectable characteristic indicative of concentration of the at least one analyte in the water sample, and the detectable characteristic is measured by spectrophotometry to determine concentration of the at least one analyte. One or more additive components are added to the mixer and mixed with the aqueous stream, in an amount based on the concentration of the at least one analyte. A treatment fluid is prepared including the at least one water source and the one or more additive components, and thereafter pumped into a wellbore penetrating a subterranean formation. The introducing into the microfluidic mixing cell and the measuring by spectrophotometry are conducted over an elapsed time period of about 5 minutes or less in some cases, or even over an elapsed time period of about 1 minutes or less.
Certain embodiments of the disclosure will hereafter be described with reference to the accompanying drawings, wherein like reference numerals denote like elements. It should be understood, however, that the accompanying figures illustrate the various implementations described herein and are not meant to limit the scope of various technologies described herein, and:
The following description of the variations is merely illustrative in nature and is in no way intended to limit the scope of the disclosure, its application, or uses. The description and examples are presented herein solely for the purpose of illustrating the various embodiments of the disclosure and should not be construed as a limitation to the scope and applicability. In the summary and this detailed description, each numerical value should be read once as modified by the term “about” (unless already expressly so modified), and then read again as not so modified unless otherwise indicated in context. Also, it should be understood that a range listed or described as being useful, suitable, or the like, is intended that any and every value within the range, including the end points, is to be considered as having been stated. For example, “a range of from 1 to 10” is to be read as indicating each and every possible number along the continuum between about 1 and about 10. Thus, even if specific data points within the range, or even no data points within the range, are explicitly identified or refer to only a few specific, it is to be understood that inventors appreciate and understand that any and all data points within the range are to be considered to have been specified, and that inventors possession of the entire range and all points within the range.
Unless expressly stated to the contrary, “or” refers to an inclusive or and not to an exclusive or. For example, a condition A or B is satisfied by anyone of the following: A is true (or present) and B is false (or not present), A is false (or not present) and B is true (or present), and both A and B are true (or present).
In addition, use of the “a” or “an” are employed to describe elements and components of the embodiments herein. This is done merely for convenience and to give a general sense of concepts according to the disclosure. This description should be read to include one or at least one and the singular also includes the plural unless otherwise stated.
The terminology and phraseology used herein is for descriptive purposes and should not be construed as limiting in scope. Language such as “including,” “comprising,” “having,” “containing,” or “involving,” and variations thereof, is intended to be broad and encompass the subject matter listed thereafter, equivalents, and additional subject matter not recited.
Also, as used herein any references to “one embodiment” or “an embodiment” means that a particular element, feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. The appearances of the phrase “in one embodiment” in various places in the specification are not necessarily referring to the same embodiment.
Some method embodiments are directed to producing treatment fluids, such as fracturing fluids, based on the well site analysis of water from one or more sources. In their most basic form, some methods achieve a goal by providing at least one water sample, analyzing the water sample for types and quantities of contaminants or other impurities, and formulating a fracturing fluid composition based thereon. As used herein, the terms “contaminants” and “impurities” may be used interchangeably to include any non-water molecule components found in the water sample. Additionally, as used herein, the location proximate to the well site can be a remote laboratory facility accessible to the operator of the well site without substantial loss of well operating time. As those of ordinary skill in the art will appreciate from the disclosure that follows, there are many different ways of analyzing the water samples for types and quantities of contaminants or other impurities, and many different ways of formulating a treatment fluid composition.
The inventors have discovered that use of microfluidic techniques to analyze water from one or more sources is rapid, and requires a small amount of sample and reagent. Since this technique uses laminar flow regime and small diffusion path length, it is more repeatable, reproducible, and less susceptible to operator errors. The technique has small footprint and is therefore suitable for onsite and mobile applications. The technique also poses less health and safety risks due to the very small volumes of material being used. Microfluidics enable miniaturization and utilization of many phenomena that dominate the small scale physics. By reducing the size of the flow path, the diffusion length is reduced, and therefore reactions occur more rapidly. Furthermore, the flow regime is contained within the bounds of laminar flow, which leads to more repeatable and reproducible reactions and measurements.
In some aspects of the disclosure an instrument for performing chemical analysis is provided as part of methods to analyze water samples as part of a treatment fluid preparation and delivery operation. The instrument operates analogously to standard techniques of analytical chemistry where visually observed titration of acid with standard base solution in presence of a colored indicator, and color change indicates a transition, or the colorimetric determination of the concentration of a species in aqueous solution, or the like. The instrument does the chemical mixing and processing with significant efficiency due to the use of a microfluidic flow cell for mixing. The observations can be made in the same flow cell or an adjacent optical cell. Some advantages include high reproducibility of tests, small sample volumes, greatly reduced cycle time for the measurement, higher precision of measurement, better accuracy of measurement, and increased sensitivity compared with standard laboratory bench tests. The instrument may have several parallel microfluidic devices simultaneously performing different small experiments.
Some embodiments of the disclosure may use valves and/or pumps to manipulate the various liquids that are combined and mixed in the microfluidic device. The microfluidic cell itself may be transparent to light and can be organized and structured in a variety of ways to afford (1) a controlled path length for fluid flow that exerts a specific shear/mixing energy on the liquid(s), and (2) a controlled optical/voltammetric cell of known dimensions for measuring the parameter of interest (e.g. fluorescence, absorption, conductivity). In addition, the cell, which is selected to be small, and made of sturdy resilient material, which may be heated and pressurized quickly and reliably. These two factors can contribute positively to reduced cycle time in measurement, and are frequently more accurately representative of actual field conditions for measurements that need to simulate wellbore conditions.
Methods may utilize such instruments for the on-location analysis of source water which is produced or flowback water. In some aspects, an operator would obtain a sample of water for analysis and a small amount of the water would be introduced to a reservoir in the instrument. In some other aspects, a sample of water may be pumped from the source, and a small amount of the water would be introduced into a reservoir in the instrument. The instrument useful in some method embodiments includes a plurality of additional reservoirs for various chemical reagents that are appropriate for the various analyses to be performed. The instrument's control function includes an instruction set appropriate to each of the analyses that are required—for example, in the analysis of boron, the protocol as outlined by D. L. Callicoat & J. D. Wolszon in Anal. Chem., 1959, 31 (8), pp 1434-1437, incorporated herein in its entirety, is to acidify the sample with sulfuric acid and then age the mixture in the presence of excess carminic acid. The intensity of color of the resulting boron-carminic acid complex is compared to a calibration curve which allows for direct evaluation of concentration of boron. These steps are automated into the instrument, thus removing operator error as a variable—the device would add a pre-acidified carminic acid solution to the sample and mix in the microfluidic channel. The colored solution would exit the mixing channel and fill the view cell, where color intensity is determined by an inexpensive spectrophotometer (i.e. a diode, a single-wavelength device, and the like). If required, the calibration curve can also be automated. By extension, several different workflows for different ions or chemical species in solution can be automated in parallel. Where there is overlap in the workflows, the same components may be used if the overall work process allows this. Also, It will be understood by one of ordinary skill in the art that other conventional analysis techniques may be employed to analyze the water sample in an efficient and simplistic manner at or proximate the well site. One non-limiting example includes analyzing light transmittance. In such an analysis, an optical reader, such as a colorimeter or filter photometer, is used to evaluate the color reaction according to the transmitted light method. A light beam is passed through the sample, and the amount of light transmitted depends on the amount of color present in the sample. For example, if the sample is very dark in color, limited light will pass through, which indicates a high analyte concentration. Other suitable detection techniques are within the scope of the disclosure, including, but not limited to, near infrared (NIR), fluorescent spectroscopy, resistivity, and the like.
Some embodiments of the disclosure also relate to techniques used for treating hydrocarbon-bearing subterranean formations—such as to increase the production of oil/gas from the formation and more particularly, a process for treating a subterranean formation by optimizing fluids for and even during treatment. Subterranean formation treatments include, but are not limited to, fracturing, acidizing, wellbore cleanout, gravel packing, acid diversion, cementing, fluid loss control, placing a pill, and the like. The techniques may also be applied to preparation and delivery of drilling mud and completion fluids. Some methods in accordance with the disclosure employ continuous real time analysis of boron concentration in supplied aqueous medium useful for blending with viscosifying agents or other components rheology model that directly describes the chemical reactions that occur in a crosslinked viscosifying agent based treatment fluid. One example of such a fluid is a borate-crosslinked guar-based fracturing fluid.
As used herein, the term “flowback” will be understood to mean the process of allowing fluids to flow from the well following a treatment, either in preparation for a subsequent phase of treatment or in preparation for cleanup and returning the well to production. One example of treatment employed within the scope of the disclosure is hydraulic fracturing. The term “hydraulic fracturing” as used herein refers to the injection of a viscous or slickwater fracturing fluid into a subterranean formation or zone at a rate and pressure sufficient to cause the formation or zone to break down with the attendant production of one or more fractures. The continued pumping of the viscous fracturing fluid extends the fractures, and a proppant such as sand or other particulate material may be suspended in the fracturing fluid and introduced into the created fractures. The proppant material functions to prevent the formed fractures from closing upon reduction of the hydraulic pressure which was applied to create the fracture in the formation or zone whereby conductive channels remain through which produced fluids can readily flow to the well bore upon completion of the fracturing treatment.
Depending on the water source, the sample of water can contain contaminants or other impurities subject to analysis, or otherwise termed “analytes”, where the contaminants can originate from natural sources or man-made sources. For example, a sample of water taken from a water source utilized in high-viscosity fracturing operations can contain gellants in the form of polymers with hydroxyl groups, such as guar gum or modified guar-based polymers; cross-linking agents including borate-based, titanium-based or zirconium-based cross-linkers; non-emulsifiers; and sulfate-based gel breakers in the form of oxidizing agents such as ammonium persulfate. A sample of water taken from a water source utilized in drilling fluid treatments can include acids and caustics such as soda ash, weighting agents such as barite, calcium carbonate, sodium hydroxide and magnesium hydroxide, bactericides, defoamers, emulsifiers, filtrate reducers, shale control inhibitors, deicers including methanol and thinners and dispersants. Also, a sample of water taken from a water source utilized in slickwater fracturing operations can include viscosity reducing agents such as polymers of acrylamide.
Water samples can include other impurities from one or more water sources that can influence the relative amounts of ingredients used to prepare treatment fluids. In at least one embodiment, the water sample includes one or more impurities from the group of boron, iron, iodine, calcium, sulfate, nitrate, nitrate, chloride, phosphate, magnesium, potassium, strontium, aluminum, bicarbonate, hydroxide, carbonate, arsenic, barium, bromine, chromium, cobalt, copper, manganese, nickel, silica, titanium, vanadium, zinc, zirconium, alkalinity, pH, and combinations thereof. Such impurities may naturally occur in the water source or may be introduced by activities related to oil and natural gas production. The water sample can include impurities having a buffering capacity of about 2 to about 3.5. Optionally, the water sample can include impurities having a buffering capacity of about 6.0 to about 7.2. Optionally, the water sample can include impurities having a buffering capacity of about 7.8 to about 8.8. In an alternate embodiment, the water sample includes impurities having organic content. In measurements made in embodiments of the disclosure, any suitable reagent useful for measuring a detectable characteristic may be used, including, but not limited to carminic acid, ferrozine, o-phenanthroline, chronotropic acid, Griess reagent, vanadomolybdate, o-cresolphthalein, calgamite, tannic acid, methylene blue, hydroxyanthraquinone, phenolphthalein, thymol blue, bromocresol, and any combinations thereof.
Now referencing
In
Based upon the identification and concentration 110 of analyte(s) determined, the relative amounts of water from one or more water sources (100, 102) and other components 112 (only one shown) introduced into mixing system 114 can be controlled at points 110a (in delivery conduits 116) and 110b (in conduits 118). A subterranean formation treatment fluid 120 including water from the at least one water source (100, 102) and other components 112, having desired fluid properties may then be introduced into wellbore 122 at sufficient pressure to treat the subterranean formation adjacent the wellbore at a target zone.
While
Now referring to
A water sample 206 is introduced into conduit 208, and ultimately a specific volume of sample 206 is injected into microfluidic mixing cell 202. Likewise, a specific volume of reagent 210 is injected into microfluidic mixing cell 202 by device 212. Water sample 206 and reagent 210 pass through microfluidic mixing cell 202 to produce a substantially homogenous mixture of reagent 210 and water sample 206, in a short period of time enabling unexpected elapsed time periods between introduction of the water sample and measuring the detectable characteristic(s), such periods being about 5 minutes or less, or even as low as about 1 minute or less.
To further illustrate benefits provided by arrangement 200, the mixing and processing is achieved with significant efficiency due to the use of a microfluidic mixing cell 202. As the constituent water sample 206 and reagent 210 travel simultaneously through the channel 214, significant intermixing of the constituents occurs, which is exhibited at region 216. The microfluidic mixing cell 202 may be a lamination-based compact glass microfluidic device that allows rapid mixing of two or three fluid streams in each of the two independent mixing geometries. Substantially homogenous mixing can be achieved with the system at both high as well as low flow rate ratios. The microfluidic mixing cell 202 has excellent chemical stability, high visibility (allowing access for optics), and good optical transmission. The microfluidic mixing cell 202 performs exceptionally fast, works in continuous flow mode and achieves total mixing of two or more fluid streams within milliseconds. In some embodiments, physical dimensions of microfluidic mixing cell 202 enable significant miniaturization and mobility of the arrangement. Some benefits include field deployment, real-time operation relative treatment fluid preparation, high reproducibility of tests, small sample volumes, greatly reduced cycle time for the measurement, higher precision of measurement, better accuracy of measurement, and increased sensitivity in comparison with standard bench tests.
Referring again to
As described above, in some embodiments, the device or arrangement 200 the device only injects and mixes the reagent with the water sample, and waiting is not required. Then the reagent and water sample 206 are mixed in the microfluidic mixing cell 202. This may be achieved by introducing water sample 206 into a rotating valve 222 through conduit 208 into port 6 of rotating valve. Water sample 206 then passes through a sample loading loop 224 fluidly connected with ports 1 and 4 of rotating valve 222, as depicted in
Rotating valve 222 may advance to a next position as depicted in
The events illustrated above and shown in
Now referring to
In an embodiment, the analyte contained in water source (304 and/or 306) is a crosslinker, such as borate ions, and at least one component is supplied from additive sources (316, 318) which is crosslinkable with the crosslinker. For example, guar, or its derivatives are commonly known as crosslinkable with borate ions. In the case that a guar, or guar derivative, and borate crosslinker are supplied from additive sources (316, 318) for mixing in mixer 314 with water from water source (304 and/or 306), and where a select ratio of the two components is important, measuring and understanding the borate ion content in water supplied from the water source(s) is very advantageous. Understanding the borate ion content in water mixed with the viscosity controlling additive components, such as borate ions and guars, allows more precise tailoring of the treatment fluid composition to achieve desired fluid properties for the treatment. An advantage of performing the measurement of the analyte in the method set forth above include a real time, or near real time, assessment of analyte content, in order to tailor the treatment fluid composition. Additionally, any variation in analyte content in the water source(s) as they are streamed into the mixer over time, may be detected as well. Further, unexpected spikes or sharp increases in fluid viscosity may be avoided, or curtailed, thus minimizing damage to the mixing, pumping equipment, piping and/or wellbore.
Referring again to
While generally a mixer 314 and blender 334 are depicted in
Referring again to
In another embodiment of the disclosure, another method of preparing a subterranean formation treatment fluid is provided. With reference to
As depicted in
In some embodiments, data regarding information and properties of the well to be treated and desired properties of the oilfield fluid composition are entered into the formulation database. The well data may be entered manually utilizing methods discussed above regarding the analyte(s) concentration or the data may be entered automatically through the use of sensors or other electronic methods. For example, the formulation database may be in electronic communication with sensors capable of determining well temperature and pressure. Optionally, the data may be entered automatically, manually, and or in combinations thereof. Well data entered into the formulation database for the well to be treated can include temperature and pressure. Desired fluid properties of the oilfield fluid composition can also be entered, wherein the desired fluid properties can include pH, initial viscosity, viscosity delay slope, final broken viscosity, sand transport time, onset of crosslinking, type of gelling agent, type of crosslinker, type of breaker, types of other additives (scale inhibitor), type of biocide, type of paraffin control, type of clay control, and combinations thereof.
In another embodiment, the formulation database generates a fluid model, wherein the fluid model can be utilized to formulate a fluid composition, which will be discussed in further detail below. The formulation database includes physical and chemical properties related to the analytes and the well to be treated. The formulation database can also include fundamental physical and chemical relationships, empirical evidence, algorithms based on testing results, and the like. In an embodiment, the formulation database is in an electronic format and can be located on a computer at the well site. Optionally, the formulation database can be hosted on a remote server accessible by a computer located at the well site.
The formulation database may generate a fluid model utilized to formulate a fluid composition. Specifically, the fluid model provides a recommendation on the composition of the formulation fluid to be used. The recommendation can include concentration of gelling agent, concentration of crosslinker, concentration of buffers, concentration of breaker, concentration of other additives, and combinations thereof. The fluid model may be generated in various formats. In an embodiment, the fluid model may be generated in a spreadsheet format, a report format, a graphical format, a tabular format, and combinations thereof. The fluid model can be in an electronic format and can be located on a computer at the well site. Optionally, the formulation database can be hosted on a remote server accessible by a computer located at the well site. The computer can be operatively connected to at least one fluid producing device, wherein one or more signals generated by the computer in reference to the fluid model can include instructions on fluid composition to be generated by the fluid producing device.
In an exemplary embodiment, at least one recommendation included in the fluid model generated by the formulation database is acted upon by the operator of the well site to produce a fluid composition suitable for use as a fracturing fluid. In an embodiment, the fracturing fluid will have one or more of the following properties configured according to the recommendations provided in the oilfield fluid model: pH, initial viscosity, viscosity delay slope, final broken viscosity, sand transport time, onset of crosslinking, type of gelling agent, type of crosslinker, type of breaker, types of other additives (scale inhibitors), type of biocide, type of paraffin control, type of clay control, and combinations thereof.
Formation and downhole pressure and temperature can have an impact on fluid rheology. In the case of pressure, when there is adequate pressure present in the treatment or delivery environment, the effective crosslinking functionality of a crosslinking agent, such as a borate, may be significantly reduced. Such pressures are those on the order of magnitude of 103 psi or greater, such 4×103 psi or greater. At 4×103 psi, measured viscosity is about half of the viscosity of a borate crosslinker at ambient surface pressure. Thus, the pressure affects on a borate crosslinker can be taken into account in some embodiments, and methodologies in accordance with the disclosure further improved the precision in prepared borate crosslinked treatment fluids.
Methods of the invention may also be useful for real-time QA/QC of the fluids, thus making possible to adjust the fluid components during an operation to achieve a further optimized fluid and treatment schedule. As described above, a rheology model can be used to further extrapolate monitored surface characteristics such as viscosity, pumping rate, temperature, polymer concentration, crosslinker concentration, breaker concentration to bottom-hole conditions.
In addition to preparing a treatment fluid, such as a fracturing fluid, embodiments of the disclosure may be useful for generating measurements could be used for measuring boron, or any other applicable analytes, in such processes involving ground water analysis, stock tank analysis, boron removal for environmentally friendly discharge, preparing drilling fluid, cementing fluid, acidizing fluid, completion fluid, gravel packing fluid, and the like, as well as wellbore flow back testing and environmental measurements and monitoring. The measurement could be used as a “live” measurement with a feedback loop to control the flow and chemicals, or in a batch mode prior to injection as well.
The following examples are presented to illustrate the use and some benefits of microfluidic mixing cells with optical cells, and should not be construed to limit the scope of the disclosure, unless otherwise expressly indicated in the appended claims. All percentages, concentrations, ratios, parts, etc. are by weight unless otherwise noted or apparent from the context of their use.
In a first example, a microfluidic based instrument (also referred to as “current device” or “current system” herein) was constructed for the detection of analytes, such as boron, in aqueous media, and compared to existing commercial methods. The boron value of four field water samples was measured in the instrument and compared against ICP-MS results. The current device was constructed having components generally described in
A carminic acid method was used which is a colorimetric assay where the chemical reaction between boron and the acid induces a color change in the solution (see Callicoat, 1959; Gupta and Boltz, 1974). For boron and a 10 mm absorption path, the color developed can be measured at wavelengths between 575 nm and 750 nm with a sensitivity decreasing with the increasing wavelength. Based on the carminic acid assay, a three factor improvement in sensitivity was observed. For a similar end of reaction absorption, a much shorter development time is observed: about 1 minute versus 30 minutes. High sensitivities (6.30×10−2 a.u/ppm) with good reproducibility (1% at 95% confidence), a low limit of detection (0.2 ppm) and a 3.5% precision characterize the instrument and method of using. The instrument was capable of determining boron in samples containing up to 40000 mg/l of chloride over a range of 0-500 ppm [B]. With higher back pressure, determining boron in samples containing chloride concentrations higher than 40000 mg/l is possible. Interferences from ionic species are reported and experimentally quantified for the nitrate case. The carminic acid method proved to be highly sensitive to boron.
Samples and carminic acid reagent were mixed in the microfluidic mixer and the color change was recorded with the spectrophotometer. Light absorption of the solution at a specific wavelength (610 nm±1 nm) was proportional to the boron concentration (in accordance with Beer-Lambert's law). The results listed in Table 1 were obtained at ambient temperature. A 1 cm absorption flow cell with a mixing ratio of carminic acid to sample of 5:1 (v:v) was used. Sensitivity, limit of detection and measuring range are scalable with the path length of the cell. Definition of the terminology used in table 1 can be found in the International Vocabulary of Metrology (VIM) report by the Joint Committee for Guides in Metrology (JCGM_200_2008 VIM.pdf).
Interferences from ionic species are reported and experimentally quantified for the nitrate case. The carminic acid method for the determination of boron is the least sensitive to interferences (Callicoat, 1959; Lòpez et al., 1993). False positives and negatives in presence of high concentrations of certain ionic species (nitrate, strong oxidants, transition metals) are nonetheless reported (Aznarez et al., 1985; Gupta and Boltz, 1974; Lòpez et al., 1993; Ross and White, 1960). Table 2 summarizes the most common interferences reported in the literature. When applicable, masking agents and concentration limits are given.
With the exception of nitrate (Rosenfeld and Selmer-Olsen, 1979), the quantitative relationship between the interferent and the carminic acid was not studied, and only limits were reported. The sensitivity to pH and the use of buffers to control the pH of the sample were noted (Evans and Krahenbühl, 1994).
In another example, sensitivity and reproducibility of the sensitivity are compared. The sensitivity S of a technique is defined as the absorption change (a. u.) induced by a 1 ppm concentration variation. This value can be expressed in a. u./ppm or in ppm−1 and corresponds to the slope of the calibration curve when plotting absorption versus concentration, as shown in
The reproducibility of the sensitivity of the current device or system and manual measurements is represented
In another example, the measurement time and affect thereof, were evaluated. For the current device, with a development time seven times shorter than typical manual methods, the color change was 50% higher at 610 nm (see
In another example, due to the nature of some of the waters to be measured, chloride concentrations can be relatively high, in the order of 50-60 g/l for the average water sample and higher than 200 g/l. In this study, NaCl was added incrementally to a 10 ppm boron standard and then measured using the current device with a 6 bar back pressure element. For [Cl−]<100,000 mg/l, no chemical interferences were observed. However, the air bubbles (HCl) generated by the reaction of sulfuric acid with the salt impaired the optical measurement. No reliable data could be collected for [Cl−]>100,000 mg/l. Nitrate ions were also evaluated. Nitric acid was used as a nitrate (NO3) standard and added to a 10 ppm B standard to study its impact on the carminic acid complex absorption (Ross and White, 1960). A strong false positive (15% signal change for a 50 ppm NO3− addition) was observed as shown in
In yet another example, boron analyte concentration was determined in oilfield water samples using the current device, according to some method embodiments of the disclosure. Four different water samples with their certificate of analysis from an external laboratory were tested using the current device. Results and comparison against other techniques are presented in
The effect of filtering (0.2 μm pre-filtering) and decanting of the sample were also evaluated. The influence was found to be insignificant. However, agitating the sample before measurement and pre-filtering may be useful to avoid particles blocking the passages in the microfluidic mixing cell of the current device.
Chemicals used in the foregoing examples were sourced and handled as follows: carminic acid, 99.999% sulfuric acid and boric acid were sourced from Sigma Aldrich; and, deionized water was supplied by ThermoScientific. To prevent contamination from borosilicate glass each solution was prepared and stocked into plastic vessels. Sulfuric acid resistant bottles (polymethylpentene, PMP) and graduated cylinders were used to store the reagent. The colorimetric reagent was prepared by dissolving 276 mg of carminic acid in 250 ml of 99.999% sulfuric acid and left overnight to fully dissolve. A 1-litre boron stock solution (1,000 ppm) was prepared by dissolving 5.6364 g of boric acid in deionized water. Serial dilutions of the stock solution provided the daily prepared working standards (0-200 ppm).
The foregoing description of the embodiments has been provided for purposes of illustration and description. Example embodiments are provided so that this disclosure will be sufficiently thorough, and will convey the scope to those who are skilled in the art. Numerous specific details are set forth such as examples of specific components, devices, and methods, to provide a thorough understanding of embodiments of the disclosure, but are not intended to be exhaustive or to limit the disclosure. It will be appreciated that it is within the scope of the disclosure that individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.
Also, in some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail. Further, it will be readily apparent to those of skill in the art that in the design, manufacture, and operation of apparatus used in methods to achieve that described in the disclosure, variations in apparatus design, construction, condition, erosion of components, gaps between components may present, for example.
Although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms may be only used to distinguish one element, component, region, layer or section from another region, layer or section. Terms such as “first,” “second,” and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the example embodiments.
Spatially relative terms, such as “inner,” “outer,” “beneath,” “below,” “lower,” “above,” “upper,” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. Spatially relative terms may be intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the example term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.
Although a few embodiments of the disclosure have been described in detail above, those of ordinary skill in the art will readily appreciate that many modifications are possible without materially departing from the teachings of this disclosure. Accordingly, such modifications are intended to be included within the scope of this disclosure as defined in the claims.
This application claims the benefit of U.S. Provisional Application No. 61/971,960 filed Mar. 28, 2014, which is incorporated herein in its entirety.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2015/022664 | 3/26/2015 | WO | 00 |
| Number | Date | Country | |
|---|---|---|---|
| 61971960 | Mar 2014 | US |
