This disclosure relates to water separation systems for use in hydrocarbon production wells.
Hydrocarbon wells are used to access and extract hydrocarbons from subterranean hydrocarbon reservoirs. The hydrocarbons produced from these reservoirs are often saturated with water, such as entrained formation water from the reservoirs. The produced water and hydrocarbon gas or fluid is transported across a pipeline to a downstream processing plant for water separation and process gas treatment. The separated water is then transported across a second pipeline back to the wellbore for reinjection back into the reservoir.
This disclosure describes well systems with water separation systems for separating water from a wellbore production fluid and reinjecting the separated water back into a reservoir.
In some aspects, a water separation system for a well includes a production control valve fluidly connected to a production tubing and positioned at an uphole end of the production tubing at a well head of a well site, a production fluid pathway between the production control valve and a water separator to direct a production fluid from the production control valve to the water separator, an injection control valve fluidly connected to an injection tubing and positioned at an uphole end of the injection tubing at the well head, an injection fluid pathway between the injection control valve and the water separator to direct separated water from the water separator to the injection control valve, the water separator positioned at the well site and fluidly connected to the production fluid pathway and the injection fluid pathway, the water separator to receive the production fluid, separate water from the production fluid, and direct the separated water to the injection fluid pathway, and an output fluid pathway fluidly connected to the water separator to direct the production fluid out of the water separator.
This, and other aspects, can include one or more of the following features. The water separation system can further include a second stage production control valve positioned in the output fluid pathway downstream of the water separator, the second stage production control valve to control a pressure of the production fluid in the output fluid pathway. The water separator can include a knock out drum to separate water from the production fluid. The water separation system can further include a water injection pump in the injection fluid pathway between the knock out drum and the injection control valve, the water injection pump to increase a fluid pressure of the separated water in the injection fluid pathway. The water separation system can further includes a turbocharger fluidly connected to the injection fluid pathway and to the output fluid pathway, the turbocharger to extract energy from the production fluid to boost a pressure of the separated water in the injection fluid pathway. The turbocharger can be disposed in the output fluid pathway in parallel with second stage production control valve. The turbocharger can be disposed in the injection fluid pathway in parallel with a bypass valve in the injection fluid pathway. The water separation system can further include a hydraulic recovery turbine in the output fluid pathway, the hydraulic recovery turbine to generate electrical energy from a pressure drop in a flow of the production fluid through the output fluid pathway. The hydraulic recovery turbine can be disposed in the output fluid pathway in parallel with the second stage production control valve. The water separation system can further include a turbocharger fluidly connected to the injection fluid pathway and to one of the output fluid pathway or the production fluid pathway, the turbocharger to extract energy from the production fluid to boost a pressure of the separated water in the injection fluid pathway. The water separator can include an in-line cyclonic separator. The turbocharger can include a pump section and a turbine section rotatably coupled to the pump section, the turbine section to receive a flow of the production fluid, and the pump section to boost pressure of a flow of the separated water. The turbocharger can be fluidly coupled to the injection fluid pathway downstream of the water separator and fluidly coupled to the production fluid pathway upstream of the water separator. The turbocharger can be fluidly coupled to the injection fluid pathway downstream of the water separator and fluidly coupled to the output fluid pathway downstream of the water separator. The water separation system can include a cooler along the production fluid pathway upstream of the water separator, the cooler to decrease a temperature of the production fluid in the production fluid pathway. The water separation system can further include a process control unit communicably connected to the production control valve, the injection control valve, and the output fluid pathway to control a flow of fluid through the water separation system.
Certain aspects of the disclosure encompass a method for water separation at a well site. The method includes directing, with a production fluid pathway, a first flow of a production fluid from a production control valve to a water separator, the production control valve fluidly connected to a production tubing and positioned at an uphole end of the production tubing at a well head of a well site, separating water from the first flow of production fluid with a fluid separator positioned at the well site and fluidly connected to the production fluid pathway, directing, with an injection fluid pathway, a flow of the separated water from the fluid separator to an injection control valve fluidly connected to an injection tubing and positioned at an uphole end of the injection tubing at the well head, and directing, with a output fluid pathway fluidly connected to the water separator, a second flow of the production fluid out of the water separator.
This, and other aspects, can include one or more of the following features. Directing the second flow of production fluid out of the water separator can include controlling a pressure of the second flow of production fluid in the output fluid pathway with a second stage production control valve positioned in the output fluid pathway downstream of the water separator. Separating water from the first flow of production fluid with a fluid separator comprises separating water from the first flow of production fluid with one of a knock out drum or an in-line cyclonic separator. Directing the flow of separated water from the fluid separator to the injection control valve can include boosting, with a turbocharger, a pressure of at least a portion of the flow of separated water in the injection fluid pathway. The turbocharger can be fluidly connected to the injection fluid pathway and to the output fluid pathway, and boosting the pressure of at least a portion of the flow of separated water in the injection fluid pathway can include extracting energy from the second flow of production fluid in the output fluid pathway and transferring the extracted energy to the at least a portion of the flow of separated water with the turbocharger. The turbocharger can be fluidly connected to the injection fluid pathway and to the production fluid pathway, and boosting the pressure of at least a portion of the flow of separated water in the injection fluid pathway can include extracting energy from the first flow of production fluid in the production fluid pathway and transferring the extracted energy to the at least a portion of the flow of separated water with the turbocharger. The method can further include cooling, with a cooler along the production fluid pathway upstream of the water separator, the first flow of production fluid in the production fluid pathway. Directing the second flow of the production fluid out of the water separator can include directing at least a portion of the second flow of the production fluid to a hydraulic recovery turbine disposed in the output fluid pathway, and the method can include generating electrical energy from a pressure drop of the at least a portion of the second flow of the production fluid through the output fluid pathway. The method can further include directing the generated electrical energy from the hydraulic recovery turbine to an electrical component of the well head of the well site. The method can include controlling, with an advanced process controller connected to at least one of the production control valve, the injection control valve, or the output fluid pathway, the flow of fluid through the water separator and through the output fluid pathway.
In certain aspects, a water separation system for a well includes a production fluid pathway between a production tubing at a well head of a well site and a water separator, the production fluid pathway to direct a flow of production fluid from the production tubing to the water separator, an injection fluid pathway between the water separator and an injection tubing at the well head of the well site, the injection fluid pathway to direct a flow of separated water from the water separator to the injection tubing, the water separator positioned at the well site and fluidly connected to the production fluid pathway and the injection fluid pathway, the water separator to receive the flow of production fluid, separate water from the flow of production fluid, and direct the separated water to the injection fluid pathway, an output fluid pathway fluidly connected to the water separator to direct the flow of production fluid out of the water separator, and a process control unit communicably connected to the production fluid pathway, the injection fluid pathway, the water separator, and the output fluid pathway, the process control unit to control a flow of fluid through the water separation system.
This, and other aspects, can include one or more of the following features. The water separation system can further include a turbocharger fluidly connected to the injection fluid pathway and to one of the output fluid pathway or the production fluid pathway, and communicably connected to the process control unit, the turbocharger to extract energy from the production fluid and boost a pressure of the separated water in the injection fluid pathway. The water separation system can further include a hydraulic recovery turbine fluidly connected to the output fluid pathway and communicably connected to the process control unit, the hydraulic recovery turbine to generate electrical energy from a pressure drop in a flow of production fluid through the output fluid pathway.
The details of one or more implementations of the subject matter described in this disclosure are set forth in the accompanying drawings and the description below. Other features, aspects, and advantages of the subject matter will become apparent from the description, the drawings, and the claims.
Like reference numbers and designations in the various drawings indicate like elements.
This disclosure describes water separation systems for water separation and reinjection at a production well site. A water separation system includes a production control valve at a well head of a production tubing, an injection control valve at the well head of a water injection tubing, and a water separator at the well site that fluidly connects to the production control valve and the injection control valve. The control valves can take the form of a choke valve or other type of control valve for controlling a flow through the respective valve. The water separator can take the form of a knock out drum (KOD), an in-line cyclonic separator, or another separator type that separates production fluid (such as hydrocarbon gas, hydrocarbon liquid, or two-phase production hydrocarbons) from water (for example, free water or non-free water from a hydrocarbon reservoir), and feeds the separated water back to the injection control valve, for example, without the need for a water injection pump. In some instances, the water separation system includes a turbocharger to recover potential energy from the production fluid flow, convert the recovered energy to rotational kinetic energy within the turbocharger, and apply that energy to the separated water. This application of energy to the separated water can act to boost a pressure of the separated water flow from the water separator to a pressure level sufficient for reservoir reinjection, for example, without requiring a separate water injection pump to boost the pressure of the separated water. In certain implementations, the water separation system includes a cooler in the production fluid stream between the production control valve and the water separator to condense water and dehydrate the production fluid in the production fluid stream from the well head, for example, to more efficiently and more completely separate the water component from the remainder of the production fluid.
In some conventional water separation and reinjection operations, such as the example processing system 100 of
The example well system 202 of
The example water separation system 200 includes a water separator 220 to separate water from the production fluid, for example, from the production tubing 206. The water separator 220 is located and positioned at the well site, for example, in close proximity to the production well 204 of the well system 202. The water separator 220 fluidly connects to the production tubing 206 with a production fluid pathway 222 that extends from the production tubing 206 to an input of the water separator 220, and fluidly connects to the injection tubing 212 with an injection fluid pathway 224 that extends from an output of the water separator 220 to the injection tubing 212. The production fluid pathway 222, injection fluid pathway, or both, include a pipeline or tubing, where the production fluid pathway 222 direct the flow of production fluid from the production tubing 206 to the water separator 220, and the injection fluid pathway 224 directs the flow of separated water from the water separator 220 to the injection tubing 212.
The example water separation system 200 includes a production control valve 226 fluidly connected to the production tubing 206 and the production fluid pathway 222, and is positioned at an uphole end of the production tubing 206, for example, at the well head 208 of the well system 202. The production control valve 226 controls the flow of the production fluid from the production tubing 206 as it flows into and through the production fluid pathway 222. The example water separation system 200 also includes an injection control valve 228 fluidly connected to the injection tubing 212 and the injection fluid pathway 224, and is positioned at an uphole end of the injection tubing 212, for example, at the well head 208 of the well system 202. The injection control valve 228 controls the flow of the separated water from the water separator 220 as it through the injection fluid pathway 224 and into the injection tubing 212. In some examples, the production control valve 226, the injection control valve 228, or both, take the form of a choke valve that can vary the flow of a fluid by opening (partially or completely) or closing (partially or completely) the respective valve.
The water separation system 200 includes an output fluid pathway 230 fluidly connected to an outlet of the water separator 220. The output fluid pathway 230 receives the output production fluid after all or a portion of the water component is removed from the production fluid that enters the water separator 220. The output fluid pathway 230 directs the output production fluid out of the water separator 220, for example, to a downstream pipeline 232 leading to a hydrocarbon processing facility 234, other processing facility type, or a different destination.
The example water separation system 200 of
In some implementations, the operating pressure of the separated water in the injection fluid pathway 224 from the KOD is around 2,100 pound per square inch gauge (psig) and the operating temperature is about 190 degrees Fahrenheit (F). However, the operating pressure of the KOD can vary, for example, between 300 psig and 8,000 psig depending on the pressures in the reservoir, in the corresponding pipelines, or both. A desired injection pressure at the level of the reservoir 214 is about 500 to 600 psi above the reservoir pressure, in order for injection to be sufficiently successful. For example, if the pressure in the reservoir 214 is about 2500 psig, the injection pressure of the water at the level of the reservoir should be about 3000 psig or greater. In the example water separation system 200 of
For example, in instances where the water separator 220 operates at 200 psig or similar, the total pressure of the separated water at reservoir level without the water injection pump 304 would be about 2,620 psig. The water injection pump 304 can be utilized to increase the pressure of the separated water at the surface by about 500 psig, which would then increase the total pressure of the separated water at reservoir level above the pressure threshold of about 500 psig above reservoir pressure.
The turbocharger 402 extracts energy from the flow of production fluid through the output fluid pathway 230 and transfers that energy to the separated water flow in the injection fluid pathway 224. The transferred energy can be used to boost a pressure of the separated water, for example, to reach a minimum pressure threshold sufficient for reinjection back into the reservoir 214. Alternatively, in some instances, the turbocharger 402 can be used to extract energy from the flow of separated water in the injection fluid pathway 224 and transfers that energy to the flow of production fluid through the output fluid pathway 230. In these instances, the separated water can still have a sufficient pressure for reinjection, while transferring excess pressure to the flow of production fluid through the output fluid pathway 230, for example, in instances where the production fluid is expected to traverse considerable distance along the pipeline 232 and experience considerable drops in pressure in the pipeline 232.
In the example water separation system 400 of
In certain implementations, the turbine section 408 and the pump section 406 are switched, in that energy from the flow of separated water is extracted using the turbine section 408, and the extracted energy is imparted on the production fluid flow using the pump section 406.
In some examples, such as in the example water separation system of
The example water separation system of
The cooler 702 can take a variety of different forms. In some instances, the cooler 702 includes a heat exchanger with a first side in contact with the production fluid and a second side of the tube heat exchanger in contact with a cooling media having a lower temperature than the production fluid. The cooling media can include a water stream, a refrigerant, ambient air, or other cooling media. In some examples, the cooler 702 includes an air cooler that uses natural draft air, induced draft air, forced draft air, or a combination of these to cool the production fluid in the production fluid pathway 222.
The cooler 702 is provided in the example water separation system 700 of
The HPRT 902 harnesses the pressure drop of the output production fluid along the output fluid pathway 230, and generates electrical energy from the pressure drop in the flow of the output production fluid through the output fluid pathway 230. The HPRT 902 recovers energy from some or all of the output production fluid along the output fluid pathway 230 by reducing the pressure of the fluid. An example HPRT 902 can include a reverse-rotating centrifugal pump that recovers energy from a higher-pressure process liquid by reducing its pressure that may otherwise be wasted across throttle valves. The HPRT 902 can include a horizontal or vertical type, single stage or multistage type, or overhung or between-bearing type. The materials making up the HPRT 902 do not require special metallurgy. For example, the materials of the HPRT 902 can include carbon steel, stainless steel, chrome, a combination of these, or other materials.
In some implementations, the HPRT 902 acts as a pump with a reverse rotation, and a higher inlet pressure of a fluid relative to a lower outlet pressure of the fluid. The rotation of a rotor within the HPRT 902, which rotate in response to the high pressure fluid engaging and causing blades or vanes along the rotor to rotate, is used to generate energy, such as electrical energy when the rotor rotates relative to a stator
An HPRT 902 operates near at Best Efficiency Point (BEP). In some implementations, at a point below the BEP of the HPRT 902, the capability of the HPRT 902 to recover energy may diminish and the HPRT 902 becomes a drag on the fluid system. In some examples, the amount of electrical power recovered by the HPRT 902 can be calculated with equation 1, below:
where HP is the energy recovered by the HPRT 902, Q is the turbine capacity in gallons per minute (gpm), H is the differential head across the HPRT 902 in units of feet (ft), SG is the specific gravity of liquid, and E is the HPRT efficiency decimal.
The parallel configuration of the HPRT 902 with the second stage production control valve 236 allows for the HPRT 902 to be utilized in part, utilized in full, or bypassed entirely as the output production fluid flows along the output fluid pathway 230.
In some instances, such as in the example water separation system 900 of
The APC 904 includes and uses model predictive controllers in combination with machine learning and artificial intelligence to monitor and control the overall performance of the example system 900, for example, while manipulating the opening and flow of fluid through the production control valve 226, the injection control valve 228, fluid flow and fluid level of the separator 220, fluid pressure in the separator 220, power generated from the HPRT 902, a combination of these, or other controllable aspects of the example system 900. For example, the APC 904 can detect characteristics of the flow in the separator 220, production pathway 222, injection pathway 224, output fluid pathway 230, or a combination of these, and control the flow of fluid through the water separator 220, through the output fluid pathway 230, or both, based on the detected characteristics. For example, if the APC 904 detects a pressure of the fluid in the output fluid pathway 230 upstream of the HPRT 902 that is below a threshold pressure value, the APC can control the example system 900 such that the production fluid flows through the second stage production valve 236 and bypasses the HPRT 902 in full or in part.
The prediction models for certain process variables can be built using mechanistic models, by experiment, by using the artificial intelligence of the historical data, or a combination of these. These process variables can include production fluid flow through the 230, pressure in the separator 220, power generation or recovery at the HPRT 902 (or turbocharger), production control valve 226 opening, fluid level in the separator 220, injection flow through the injection control valve 228, or other variables. The APC 904 can be utilized to avoid violating certain hard constraints, like carbon deposition on the anode.
In some implementations, a pressure of the second flow of production fluid in the output fluid pathway is controlled with a second stage production control valve positioned in the output fluid pathway downstream of the water separator. The fluid separator can include a knock out drum, an in-line cyclonic separator, or another type of fluid separator. In some examples, the in-line cyclonic separator is a compact separator that can provide benefits in crowded installations, such as in offshore hydrocarbon well sites. Directing the flow of separated water from the fluid separator to the injection control valve can include boosting a pressure of the portion of the flow of separated water in the injection fluid pathway with a turbocharger. The turbocharger can be fluidly connected to the injection fluid pathway and to the output fluid pathway, and the turbocharger can act to extract energy from the second flow of production fluid in the output fluid pathway and transfer the extracted energy to the portion of the flow of separated water. In some instances, the turbocharger can be fluidly connected to the injection fluid pathway and to the production fluid pathway, and can act to extract energy from the first flow of production fluid in the production fluid pathway and transfer the extracted energy to the portion of the flow of separated water. In certain implementations, a portion of the second flow of the production fluid is directed to a hydraulic recovery turbine disposed in the output fluid pathway, where the hydraulic recovery turbine can generate electrical energy from a pressure drop in the second flow of the production fluid through the output fluid pathway. The generated electrical energy from the hydraulic recovery turbine can be directed to an electrical component of the well head of the well site, or to other components.
The computer 1202 can serve in a role as a client, a network component, a server, a database, a persistency, or components of a computer system for performing the subject matter described in the present disclosure. The illustrated computer 1202 is communicably coupled with a network 1230. In some implementations, one or more components of the computer 1202 can be configured to operate within different environments, including cloud-computing-based environments, local environments, global environments, and combinations of environments.
At a high level, the computer 1202 is an electronic computing device operable to receive, transmit, process, store, and manage data and information associated with the described subject matter. According to some implementations, the computer 1202 can also include, or be communicably coupled with, an application server, an email server, a web server, a caching server, a streaming data server, or a combination of servers.
The computer 1202 can receive requests over network 1230 from a client application (for example, executing on another computer 1202). The computer 1202 can respond to the received requests by processing the received requests using software applications. Requests can also be sent to the computer 1202 from internal users (for example, from a command console), external (or third) parties, automated applications, entities, individuals, systems, and computers.
Each of the components of the computer 1202 can communicate using a system bus 1203. In some implementations, any or all of the components of the computer 1202, including hardware or software components, can interface with each other or the interface 1204 (or a combination of both), over the system bus 1203. Interfaces can use an application programming interface (API) 1212, a service layer 1213, or a combination of the API 1212 and service layer 1213. The API 1212 can include specifications for routines, data structures, and object classes. The API 1212 can be either computer-language independent or dependent. The API 1212 can refer to a complete interface, a single function, or a set of APIs.
The service layer 1213 can provide software services to the computer 1202 and other components (whether illustrated or not) that are communicably coupled to the computer 1202. The functionality of the computer 1202 can be accessible for all service consumers using this service layer. Software services, such as those provided by the service layer 1213, can provide reusable, defined functionalities through a defined interface. For example, the interface can be software written in JAVA, C++, or a language providing data in extensible markup language (XML) format. While illustrated as an integrated component of the computer 1202, in alternative implementations, the API 1212 or the service layer 1213 can be stand-alone components in relation to other components of the computer 1202 and other components communicably coupled to the computer 1202. Moreover, any or all parts of the API 1212 or the service layer 1213 can be implemented as child or sub-modules of another software module, enterprise application, or hardware module without departing from the scope of the present disclosure.
The computer 1202 includes an interface 1204. Although illustrated as a single interface 1204 in
The computer 1202 includes a processor 1205. Although illustrated as a single processor 1205 in
The computer 1202 also includes a database 1206 that can hold data for the computer 1202 and other components connected to the network 1230 (whether illustrated or not). For example, database 1206 can be an in-memory, conventional, or a database storing data consistent with the present disclosure. In some implementations, database 1206 can be a combination of two or more different database types (for example, hybrid in-memory and conventional databases) according to particular needs, desires, or particular implementations of the computer 1202 and the described functionality. Although illustrated as a single database 1206 in
The computer 1202 also includes a memory 1207 that can hold data for the computer 1202 or a combination of components connected to the network 1230 (whether illustrated or not). Memory 1207 can store any data consistent with the present disclosure. In some implementations, memory 1207 can be a combination of two or more different types of memory (for example, a combination of semiconductor and magnetic storage) according to particular needs, desires, or particular implementations of the computer 1202 and the described functionality. Although illustrated as a single memory 1207 in
The application 1208 can be an algorithmic software engine providing functionality according to particular needs, desires, or particular implementations of the computer 1202 and the described functionality. For example, application 1208 can serve as one or more components, modules, or applications. Further, although illustrated as a single application 1208, the application 1208 can be implemented as multiple applications 1208 on the computer 1202. In addition, although illustrated as internal to the computer 1202, in alternative implementations, the application 1208 can be external to the computer 1202.
The computer 1202 can also include a power supply 1214. The power supply 1214 can include a rechargeable or non-rechargeable battery that can be configured to be either user- or non-user-replaceable. In some implementations, the power supply 1214 can include power-conversion and management circuits, including recharging, standby, and power management functionalities. In some implementations, the power-supply 1214 can include a power plug to allow the computer 1202 to be plugged into a wall socket or a power source to, for example, power the computer 1202 or recharge a rechargeable battery.
There can be any number of computers 1202 associated with, or external to, a computer system containing computer 1202, with each computer 1202 communicating over network 1230. Further, the terms “client,” “user,” and other appropriate terminology can be used interchangeably, as appropriate, without departing from the scope of the present disclosure. Moreover, the present disclosure contemplates that many users can use one computer 1202 and one user can use multiple computers 1202.
A number of implementations have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the disclosure.
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