Gas and Water Breakthrough Detection

This application is a divisional and claims the benefit of priority of U.S. patent application Ser. No. 18/197,938, dated May 16, 2023, the entire contents of which are incorporated by reference in its entirety.

The present disclosure relates to computer-implemented methods and systems for gas and water breakthrough detection in producing wells.

Gas and water can be injected into a subsurface oil-bearing reservoir through injection wells to maintain reservoir pressure. Gas or water breakthrough can occur when the injected gas or water breaks through to one or more of the producing wells in the oil-bearing reservoir.

The present disclosure involves computer-implemented methods and systems for gas and water breakthrough detection in producing wells. One example computer-implemented method includes receiving flow rate measurement data of produced gas and produced oil of a producing well in a subsurface reservoir. Composition measurement data of the produced gas and the produced oil are received. An occurrence of a producing well breakthrough of gas injected into the subsurface reservoir from one or more injection wells is detected based on the received flow rate measurement data and the received composition measurement data. Oil recovery from the producing well is enhanced based on the detected occurrence of the producing well breakthrough of the injected gas.

While generally described as computer-implemented software embodied on tangible media that processes and transforms the respective data, some or all of the aspects may be computer-implemented methods or further included in respective systems or other devices for performing this described functionality. The details of these and other aspects and implementations of the present disclosure are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the disclosure will be apparent from the description and drawings, and from the claims.

Like reference numbers and designations in the various drawings indicate like elements.

This disclosure relates to composition-based gas and water breakthrough detection in producing wells. A breakthrough detection system can perform the detection by analyzing the compositions of produced hydrocarbon or the salinity of produced water from a subsurface oil-bearing reservoir or field that is under the pressure maintenance by lean gas injection or water injection.

Injected gas or water can be used to displace in-situ oil to producing wells. When a breakthrough of injected gas or water occurs, the injected gas or water can find paths from the injector to the producing wells, and less in-situ oil will be displaced to the producing wells. Therefore, gas or water injection becomes less efficient in terms of sweeping oil for recovery.

When a breakthrough of injected gas in producing wells occurs, the produced gas from the producing wells can be a mixture of formation gas and the injected gas. The injected gas primarily contains lighter carbon numbers such as Cand C. An increasing trend of the mole fractions of Cand Cin produced gas over time can indicate that injected gas has entered into the producing wells due to gas breakthrough.

The produced water during a breakthrough of injected water in producing wells can be a mixture of formation water and injected fresher water. A decreasing trend of the salinity of produced water over time can be used as an indicator for the identification of the breakthrough of injected water in producing wells. Additionally, an increasing trend of water cut of the produced water from the producing wells can be combined with the aforementioned decreasing trend of the salinity of produced water to detect the breakthrough of injected water in producing wells.

A surface inline multiphase tester or multiple testing units can be used to measure the compositions of produced hydrocarbons and the salinity of produced water. The compositions of in-situ oil from a producing zone can be obtained from an initial pressure-volume-temperature (PVT) analysis report, and the compositions of injected gas can also be analyzed through the multiphase tester. The salinity of the original formation water can be obtained from the geochemical report of water samples from exploration wells in the same field or the same reservoir. As the field is being produced, the continuous analysis of both the compositions of produced hydrocarbon and the salinity of produced water can enable the identification of increase of compositions in the lighter carbon numbers of the compositions of produced hydrocarbon and drop of salinity of the produced water. The identification can flag gas breakthrough or water breakthrough.

When a breakthrough of gas or water is detected, existing perforations for gas or water injection can be cement-squeezed off, and the formation can be re-perforated in different intervals in order to change the flowing paths for the injected gas or water for displacing in-situ oil. Numerical simulation can also be performed to find any trapped oil zones where new in-fill wells can be drilled.

illustrates an example workflowfor determining an occurrence of gas breakthrough into a producing well. In some implementations, to detect the gas breakthrough into a producing well, the breakthrough detection system collects different fluid flow measurement data, water salinity measurement data, and hydrocarbon composition measurement data. For convenience, workflowwill be described as being performed by a system of one or more computers (e.g., the breakthrough detection system), located in one or more locations, and programmed appropriately in accordance with this specification.

In step, a computer system receives flow rate measurement data of produced gas and produced oil of a producing well in a subsurface reservoir that is measured over a period of time. In some implementations, the flow rate measurement data of produced gas and produced oil can be measured using a multiphase tester. The multiphase tester can be a surface multiphase tester located downstream of a wellhead. An example multiphase tester is the phase testerof.

illustrates a schematic of an oil-bearing reservoir under gas and water injection. The injected lean gasand injected watercan be put into a subsurface oil-bearing reservoir for pressure maintenance of the oil-bearing reservoir. The injected lean gasand injected watercan be from one or more injection wells in the subsurface reservoir, for example, from injection wells adjacent to the producing well. A phase testercan be used to measure the flow rates of produced oil, gas, and water from a producing well in the oil-bearing reservoir. The phase testercan be a surface multiphase tester located downstream of a wellhead. The phase testercan also measure the compositions of produced hydrocarbon and the salinity of produced water of the producing well. Additionally, the phase testercan measure the compositions of gas injected into the subsurface oil-bearing reservoir, for example, injected lean gas. Other data, for example, pressure and temperature of produced fluid stream, can also be measured by phase tester.

Returning to, in step, the computer system receives composition measurement data of the produced gas and the produced oil. In some implementations, the composition measurement data of gas injected into the subsurface reservoir, for example, injected lean gasof, can be measured by phase testerof. The composition measurement data can include mole fraction measurement data of the compositions of the injected gas.

In step, the computer system detects, based on the received flow rate measurement data and the received composition measurement data, an occurrence of a breakthrough of gas injected into the subsurface reservoir from one or more injection wells. In some implementations, this detection involves two steps.

In the first step, the computer system determines, based on the received flow rate measurement data, that a first increasing trend of gas oil ratio (GOR) of the produced gas and the produced oil occurs within a predetermined period of time. The computer system can calculate the GOR as a ratio of the measured flow rate of the produced gas to the measured flow rate of the produced oil. In some implementations, at the beginning of a gas breakthrough, the GOR may show some variations. For example, the GOR can be higher than or equal to the original GOR at the beginning of a gas breakthrough. However, the GOR can continue to increase after the initial transitional gas breakthrough or during a stabilized gas breakthrough. In some implementations, the computer system determines the first increasing trend of GOR through a regression process of the calculated GOR data over the predetermined period of time. More specifically, the computer system determines the first increasing trend of GOR if the GOR after regression is increasing over the predetermined period of time.

In the second step, the computer system determines, based on the received composition measurement data, that a second increasing trend of a total percentage of compositions of the injected gas in produced fluids of the producing well occurs within the predetermined period of time. In some implementations, the mole fractions of the carbon numbers in the compositions of the hydrocarbons produced from the producing well and affected by the gas breakthrough can depend on the compositions of injected gas (e.g., injected lean gasof). For example, when a breakthrough of injected gas in the producing well occurs, the mole fractions of Cand C, which are the lighter carbon numbers in the compositions of the injected gas, can be detected in the compositions of the hydrocarbons produced from the producing well, using, for example, a multiphase tester (e.g., phase testerof). As more injected gas gets into the producing well during the breakthrough, the mole fractions of Cand Cin the compositions of the hydrocarbons produced from the producing well can increase over time. Therefore, when the breakthrough of injected gas in the producing well occurs and during the predetermined period of time, the mole fractions of both Cand Ccan be consistently higher than the initial mole fractions of Cand Cat the beginning of the breakthrough of injected gas in the producing well, and can continue to increase during the predetermined period of time. Based on the composition data of the produced hydrocarbons from the producing well and measured by the multiphase test over the predetermined period of time, the second increasing trend can be determined using a regression process similar to the one used for determining the first increasing trend described above.

In some implementations, the computer system can select the predetermined period of time based on the formation characteristics of the producing well, such as heterogeneity and permeability.

In some implementations, once the computer system determines that both the first increasing trend and the second increasing trend occur within the predetermined period of time, it detects an occurrence of the breakthrough of the injected gas in the producing well.

In step, the computer system enhances oil recovery from the producing well based on the detected occurrence of the breakthrough of the injected gas in the producing well. In some implementations, the computer system enhances oil recovery by improving cyclic gas injection based on the detected occurrence of the breakthrough of the injected gas in the producing well. For example, existing perforations for gas injection can be cement-squeezed off, and the formation can be re-perforated in different intervals in order to change the flowing paths for the injected gas for displacing in-situ oil. Due to the complexity of the flowing paths inside the porous media such as tortuosity, change of flowing paths of the injected gas can displace more oil toward the producing well. Numerical simulation can also be performed to find any trapped oil zones where new in-fill wells can be drilled.

illustrates an example workflowfor determining an occurrence of water breakthrough into a producing well. In some implementations, to detect the water breakthrough into a producing well, a breakthrough detection system collects different fluid flow measurement data and water salinity measurement data. For convenience, workflowwill be described as being performed by a system of one or more computers (e.g., the breakthrough detection system), located in one or more locations, and programmed appropriately in accordance with this specification.

In step, a computer system receives flow rate measurement data of produced water and produced oil of a producing well in a subsurface reservoir that is measured over a period of time. In some implementations, the flow rate measurement data of produced water and produced oil can be measured using a multiphase tester. The multiphase tester can be a surface multiphase tester located downstream of a wellhead. An example multiphase tester is the phase testerof.

In step, the computer system receives salinity measurement data of the produced water of the producing well over the period of time. In some implementations, the salinity measurement data can be measured by a multiphase tester, for example, phase testerof.

In step, the computer system determines, based on the received flow rate measurement data and the received salinity measurement data, an occurrence of a producing well breakthrough of water injected into the subsurface reservoir. In some implementations, this determination process includes two steps.

In the first step, the computer system determines, based on the received flow rate measurement data, that an increasing trend of water cut of the produced water occurs within a predetermined period of time. The computer system can calculate the water cut as a ratio of the measured water flow rate to the measured total liquid rate (e.g., measured oil flow rate plus measured water flow rate) in a produced fluid stream of the producing well. In some implementations, the water cut can continue to increase during a stabilized water breakthrough. In some implementations, the computer system determines the increasing trend of water cut through a regression process of the calculated water cut data over the predetermined period of time, and an increasing trend of water cut can be determined if the water cut after regression is increasing over the predetermined period of time.

In the second step, the computer system determines, based on the received salinity measurement data, that a decreasing trend of salinity of the produced water of the producing well occurs within the predetermined period of time. The computer system can determine the decreasing trend using a regression process similar to the one used for determining the increasing trend of water cut described above.

In some implementations, the computer system can select the predetermined period of time based on the formation characteristics of the producing well, such as heterogeneity and permeability. For example, the predetermined period of time can be four to five days. A longer time interval such as ten to thirty days can also be used depending on the oil operating company.

In some implementations, once the computer system determines that both the increasing trend and the decreasing trend occur within the predetermined period of time, it detects an occurrence of the producing well breakthrough of water injected into the subsurface reservoir from one or more injection wells.

In step, the computer system enhances oil recovery from the producing well based on the detected occurrence of the breakthrough of the injected water in the producing well. In some implementations, the computer system enhances oil recovery by improving cyclic water rejection based on the detected occurrence of the breakthrough of the injected water in the producing well.

illustrates an example processof detecting gas breakthrough in producing wells. For convenience, the processwill be described as being performed by a system of one or more computers, located in one or more locations, and programmed appropriately in accordance with this specification.

In step, a computer system receives flow rate measurement data of produced gas and produced oil of a producing well in a subsurface reservoir.

In step, the computer system receives composition measurement data of the produced gas and the produced oil.

In step, the computer system detects, based on the received flow rate measurement data and the received composition measurement data, an occurrence of a producing well breakthrough of gas injected into the subsurface reservoir from one or more injection wells.

In step, the computer system enhances oil recovery from the producing well based on the detected occurrence of the producing well breakthrough of the injected gas.

illustrates a schematic diagram of an example computing system. The systemcan be used for the operations described in association with the implementations described herein. For example, the systemmay be included in any or all of the server components discussed herein. The systemincludes a processor, a memory, a storage device, and an input/output device. The components,,, andare interconnected using a system bus. The processoris capable of processing instructions for execution within the system. In some implementations, the processoris a single-threaded processor. The processoris a multi-threaded processor. The processoris capable of processing instructions stored in the memoryor on the storage deviceto display graphical information for a user interface on the input/output device.

The memorystores information within the system. In some implementations, the memoryis a computer-readable medium. The memoryis a volatile memory unit. The memoryis a non-volatile memory unit. The storage deviceis capable of providing mass storage for the system. The storage deviceis a computer-readable medium. The storage devicemay be a floppy disk device, a hard disk device, an optical disk device, or a tape device. The input/output deviceprovides input/output operations for the system. The input/output deviceincludes a keyboard and/or pointing device. The input/output deviceincludes a display unit for displaying graphical user interfaces.

Certain aspects of the subject matter described here can be implemented as a method. Flow rate measurement data of produced gas and produced oil of a producing well in a subsurface reservoir are received. Composition measurement data of the produced gas and the produced oil are received. An occurrence of a producing well breakthrough of gas injected into the subsurface reservoir from one or more injection wells is detected based on the received flow rate measurement data and the received composition measurement data. Oil recovery from the producing well is enhanced based on the detected occurrence of the producing well breakthrough of the injected gas.

An aspect taken alone or combinable with any other aspect includes the following features. Detecting the occurrence of the producing well breakthrough of the injected gas includes determining, based on the received flow rate measurement data, that a first increasing trend of gas oil ratio of the produced gas and the produced oil occurs within a predetermined period of time; determining, based on the received composition measurement data, that a second increasing trend of a total percentage of compositions of the injected gas in produced fluids of the producing well occurs within the predetermined period of time; and in response to determining that both the first increasing trend and the second increasing trend occur within the predetermined period of time, detecting the occurrence of the producing well breakthrough of the injected gas.

An aspect taken alone or combinable with any other aspect includes the following features. The one or more injection wells are adjacent to the producing well.

An aspect taken alone or combinable with any other aspect includes the following features. The composition measurement data includes mole fraction measurement data of compositions of the produced gas and the produced oil.

An aspect taken alone or combinable with any other aspect includes the following features. The flow rate measurement data and the composition measurement data are from a multiphase tester coupled to the producing well

An aspect taken alone or combinable with any other aspect includes the following features. Measurement data of the multiphase tester further includes flow measurement data of produced water from the producing well.

An aspect taken alone or combinable with any other aspect includes the following features. The multiphase tester is a surface multiphase tester.

Certain aspects of the subject matter described here can be implemented as a method. Flow rate measurement data of produced water and produced oil of a producing well in a subsurface reservoir are received. Salinity measurement data of the produced water of the producing well are received. An occurrence of a producing well breakthrough of water injected into the subsurface reservoir from one or more injection wells is detected based on the received flow rate measurement data and the received salinity measurement data. Oil recovery from the producing well is enhanced based on the detected occurrence of the producing well breakthrough of the injected water.

An aspect taken alone or combinable with any other aspect includes the following features. Detecting the occurrence of the producing well breakthrough of the injected water includes determining, based on the received flow rate measurement data, that an increasing trend of water cut of the produced water occurs within a predetermined period of time; determining, based on the received salinity measurement data, that a decreasing trend of salinity of the produced water of the producing well occurs within the predetermined period of time; and in response to determining that both the increasing trend and the decreasing trend occur within the predetermined period of time, detecting the occurrence of the producing well breakthrough of water injected into the subsurface reservoir from the one or more injection wells.

An aspect taken alone or combinable with any other aspect includes the following features. The one or more injection wells are adjacent to the producing well.

An aspect taken alone or combinable with any other aspect includes the following features. The flow rate measurement data and the salinity measurement data are from a multiphase tester coupled to the producing well.

An aspect taken alone or combinable with any other aspect includes the following features. Measurement data of the multiphase tester further includes flow measurement data of produced gas from the producing well.