Inhibiting Microbial Activity in a Subsurface Formation

Description

TECHNICAL FIELD

This disclosure relates to inhibiting microbial activity in a subsurface formation.

BACKGROUND

Hydrogen gas can be used as an energy source to decarbonize industrial sectors (e.g., transportation, manufacturing, heating) and mitigate effects of climate change. Combustion products from combusting hydrogen gas are free from harmful substances. The gravimetric energy content of hydrogen gas is larger than the gravimetric energy content of natural gas. Storage of hydrogen in underground geological formations is one option for large scale hydrogen storage. Suitable storage locations included depleted gas reservoirs, depleted oil reservoirs, artificial salt caverns, deep aquifers, hard rock caverns, and abandoned mines.

SUMMARY

Many subsurface formations suitable for large scale hydrogen storage include diverse microbial organisms (microbes). Microbes can gain energy from oxidation of electron donors and reduction of an electron acceptor. Hydrogen can be an electron donor for microbial respiration in a subsurface formation and can be used by many metabolically different groups of organisms. Oxidation of hydrogen due to microbial respiration can deplete the store of hydrogen around the microbes ultimately reducing the store of hydrogen in the subsurface formation. Further, the microbial hydrogen oxidation can result in increases in the amount of other gases such as methane or hydrogen sulfide in the subsurface formation, which may be undesirable.

This disclosure provides an approach for injecting a microbial inhibitor into a subsurface formation. Injecting microbial inhibitor into a subsurface formation used for underground hydrogen storage can prevent microbes from depleting the hydrogen supply stored in the subsurface formation. A tool can be inserted into the subsurface formation through a wellbore to inject the microbial inhibitor directly into the subsurface formation. The tool can be equipped with sensors to detect concentrations of hydrogen and/or microbes to enable targeted injection of the microbial inhibitor based on the sensed conditions in the wellbore.

A downhole tool can include a tool body and one or more tanks containing a microbial inhibitor fluid positioned within the tool body. One or more injection nozzles can be fluidly connected to the tanks containing the microbial inhibitor fluid. The injection nozzles can be extended from an outer surface of the tool body. Injection pumps in the downhole tool can pump the microbial fluid from the tanks through the injection nozzles. The downhole tool can include one or more sensors to measure a microbial concentration, a hydrogen concentration, or both. The downhole tool can include an onboard computer system disposed within the tool body. The onboard computer system can include at least one processor and a memory storing instructions executable by the at least one processor. The onboard computing system can be configured to operate the one or more injection pumps and the one or more injection nozzles to inject the microbial inhibitor fluid into a subsurface formation.

Implementations of the systems and methods of this disclosure can provide various technical benefits. The downhole tool can control injection of a microbial inhibitor into a subsurface formation based on microbial activity sensed by the downhole tool. The sensing and control can occur in real-time providing tailored injections into the subsurface formation based on the conditions in the subsurface formation. For example, the downhole tool can control injection pressures, injection quantity, and/or a type of microbial inhibitor. The injection nozzles of the downhole tool can be inserted directly into the subsurface formation to provide targeted delivery of the microbial inhibitor at specified locations within the subsurface formation. The downhole tool can be assembled of modules (e.g., a sensing module and an injection module) that improves the maintainability of the downhole tool and limits impacts on other elements of the downhole assembly.

Computing systems within the downhole tool can communicate with other computing systems within the downhole tool through a wireless network. Using wireless communications reduces the space required to connect separate computing systems by eliminating communications cables within the downhole tool. The wireless communications may be more robust in harsh environments than wired communications due to the reduced susceptibility to corroding cables or other mechanical stresses that may degrade the communications.

The details of one or more implementations of these systems and methods are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of these systems and methods will be apparent from the description and drawings, and from the claims.

DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic illustrating a subsurface formation.

FIG. 2 is a schematic illustrating a downhole wireline tool for injecting microbial inhibitor into a subsurface formation.

FIG. 3 is a schematic illustrating a Clark-type hydrogen sensor.

FIG. 4 is a flow chart for a method of injecting microbial inhibitor into a subsurface formation.

FIG. 5 is a block diagram illustrating an example computer system used to provide computational functionalities associated with described algorithms, methods, functions, processes, flows, and procedures according to some implementations of the present disclosure.

Like reference symbols in the various drawings indicate like elements.

DETAILED DESCRIPTION

Many subsurface formations suitable for large scale hydrogen storage include diverse microbial organisms (microbes). Microbes can gain energy from oxidation of electron donors and reduction of an electron acceptor. Hydrogen can be an electron donor for microbial respiration in a subsurface formation and can be used by many metabolically different groups of organisms. Oxidation of hydrogen due to microbial respiration can deplete the store of hydrogen around the microbes ultimately reducing the store of hydrogen in the subsurface formation. Further, the microbial hydrogen oxidation can result in increases in the amount of other gases such as methane or hydrogen sulfide in the subsurface formation, which may be undesirable.

This disclosure provides an approach for injecting a microbial inhibitor into a subsurface formation. Injecting microbial inhibitor into a subsurface formation used for underground hydrogen storage can prevent microbes from depleting the hydrogen supply stored in the subsurface formation. A tool can be inserted into the subsurface formation through a wellbore to inject the microbial inhibitor directly into the subsurface formation. The tool can be equipped with sensors to detect concentrations of hydrogen and/or microbes to enable targeted injection of the microbial inhibitor based on the sensed conditions in the wellbore.

A downhole tool can include a tool body and one or more tanks containing a microbial inhibitor fluid positioned within the tool body. One or more injection nozzles can be fluidly connected to the tanks containing the microbial inhibitor fluid. The injection nozzles can be extended from an outer surface of the tool body. Injection pumps in the downhole tool can pump the microbial fluid from the tanks through the injection nozzles. The downhole tool can include one or more sensors to measure a microbial concentration, a hydrogen concentration, or both. The downhole tool can include an onboard computer system disposed within the tool body. The onboard computer system can include at least one processor and a memory storing instructions executable by the at least one processor. The onboard computing system can be configured to operate the one or more injection pumps and the one or more injection nozzles to inject the microbial inhibitor fluid into a subsurface formation.

FIG. 1 illustrates a wireline operation 100 using a wireline tool 200 to inject microbial inhibitor into a subsurface formation 124. A wellbore 110 extends downhole from a wellhead 112. The wellbore 110 is a vertical wellbore but wireline operations can also be performed in other wellbores, for example, slanted or horizontal wellbores. In the wireline operation 100, the wellbore 110 penetrates through five layers 114, 116, 118, 120, 122 of a subsurface formation 124. A control truck 128 lowers the wireline tool 200 down the wellbore 110 on a wireline 136. The subsurface formation 124 can include one or more locations to store hydrogen gas within the subsurface formation (e.g., a depleted gas or oil reservoir)

As the wireline tool 200 travels downhole, sensors of the wireline tool can measure concentrations of hydrogen and/or microbes in the subsurface formation. The wireline tool 200 includes injection nozzles that can be extended from the wireline tool into the subsurface formation to enable targeted delivery of the microbial inhibitor. The wireline tool 200 can include a computing system to obtain and record the sensor measurements and control the injection of the microbial inhibitor. Alternatively, or additionally, the wireline tool 200 can be controlled from a data processing system at the control truck 128.

The wireline tool 200 can be a part of a string of multiple instruments with sensors operable to measure properties of the subsurface formation 124. For example, the string of multiple instruments can include logging tools to acquire resistivity logs, borehole image logs, porosity logs, density logs, sonic logs, and/or core samples from the wellbore 110.

FIG. 2 is a schematic of the downhole wireline tool 200 for injecting microbial inhibitor into a subsurface formation. The wireline tool 200 can be used in a wireline operation (e.g., wireline operation 100). The wireline tool 200 is shown within a wellbore 202 that has been drilled into a subsurface formation. The wireline tool 200 includes microbial inhibitor fluid to be injected into the subsurface formation through injection nozzles 210. For example, the wireline tool 200 can be run in a wellbore in a subsurface formation that stores hydrogen to inject microbial inhibitor fluid to inhibit the growth or activity of microbes in the region of the subsurface formation storing hydrogen to preserve the amount of hydrogen being stored.

The wireline tool 200 includes a tool body 204 including two tanks 214 to hold microbial inhibitor fluid. The wireline tool 200 include injection pumps 220 to pump fluid from the tanks 214 into the subsurface formation through the injection nozzles 210. The wireline tool 200 includes onboard computing systems 224, 226 to obtain measurements from the subsurface formation and to control the wireline tool 200.

The tool body 204 includes an uphole portion 206 and a downhole portion 208. The uphole portion 206 includes sensors 222 and the onboard computing system 224. The downhole portion 208 includes the tanks 214 and onboard computing system 226. The tool body 204 can be made from steel, for example. The tool body protects internal components of the wireline tool 200 form harsh conditions that can exist in a wellbore. In some implementations, the uphole portion 206 and the downhole portion 208 are separate modules (e.g., a sensing module and an injection module) that are assembled to form the downhole tool 200.

The tool body 204 two tanks 214 that can hold a microbial inhibitor fluid to be injected into the subsurface formation. The tanks 214 can hold the same microbial inhibitor fluid or each tank 214 can hold a different microbial inhibitor fluid to enable the application of the microbial inhibitor fluid to be tailored to the types of microbes present in the subsurface formation. The microbial inhibitor fluid is generally in a liquid form. The tanks 214 can be pressurized to facilitate injection of the liquid through the injection nozzles. Example microbial inhibitor fluids include tetrakis (hydroxymethyl) phosphonium sulfate (TPHS), diamine, tris(hydroxymethyl)nitromethane (THNM).

In some implementations, the wireline tool 200 includes a single tank. In some implementations, the wireline tool 200 includes 3 or more tanks. The number of tanks included in the wireline tool 200 can depend, for example, on the volume of fluid to be injected into the subsurface formation, or the number of different microbial inhibitor fluids to be injected into the subsurface formation. In some implementations, the wireline tool 200 can be connected to a source of microbial inhibitor fluid on the surface by a tube running down the wellbore, and the microbial inhibitor fluid can be pumped from the surface to the wireline tool 200 and through the injection nozzles 210.

The injection nozzles 210 extend from an outer surface 212 of the tool body 204. The injection nozzles 210 are fluidly coupled to the tanks 214. The injection nozzles 210 can have sharp tips 216 at distal ends of the injection nozzles to facilitate penetration of the injection nozzles 210 into the subsurface formation. The tips 216 can be made of, for example, titanium. The sharpness of the tips 216 can be based on the aspect ratio of the tip 216 (e.g., ratio of minimum diameter to maximum diameter). For example, a sharp tip can have an aspect ratio of 1/10 or less, 1/20 or less, 1/100 or less.

Hydraulic actuators 218 attached to the injection nozzles 210 are operative to extend the injection nozzles 210 from a retracted position near the outer surface 212 of the tool body 204 to an extended position away from the outer surface 212 of the tool body 204 and into the subsurface formation. The hydraulic actuators 218 can retract the injection nozzles 210 from the extended position to the retracted position. The hydraulic actuators 218 can provide sufficient force to the injection nozzles 210 to penetrate into the subsurface formation. The hydraulic actuators can provide a force greater than the formation pressure (e.g., 600-800 psi greater than the formation pressure).

Penetration of the injection nozzles 210 into the subsurface formation enables the microbial inhibitor fluid to be injected more uniformly into the reservoir relative to injecting the microbial inhibitor fluid into the wellbore. The injection nozzles 210 can penetrate, for example, 0.5-1 feet (15-30 cm) into the subsurface formation. The penetration depth depends on the type of rock in the formation. Example types of rock in which the downhole tool can be used include carbonates, sandstone, limestone, and other higher porous rocks, as well as salt caverns.

One or more injection pumps 220 are coupled to the tanks 214. The injection pumps 220 are operable to pump the microbial inhibitor fluid from the tanks 214 through the injection nozzles 210 into the subsurface formation. The injection pumps 220 can be, for example, pressure piston pumps that can adjust the force applied by the injection pump 220 to the tanks 214 to control the amount of microbial inhibitor fluid injected into the subsurface formation.

The wireline tool 200 includes one or more sensors 222 to measure a microbial concentration, a hydrogen concentration or both. The sensors 222 can extend from the outer surface 212 of the tool body 204 toward the walls of the wellbore 202. The sensors 222 can be pushed against the walls of the wellbore 202 to measure the microbial concentration around the formation. The sensors 222 can be positioned in the uphole portion 206 of the tool body 202. In an example, the wireline tool 200 includes four microbial sensors that each have a total length of 150-200 mm. The tip of the injection nozzles 210 is small in comparison with the sensors 222. For example, the sensors 222 can have a 20 mm diameter and the tips 216 of the injection nozzles 210 can have a 2 mm diameter tip. In some implementations, the sensors 222 can be Clark-type hydrogen sensors (see FIG. 3).

The wireline tool 200 includes onboard computing systems 224, 226. Each of the onboard computing systems 224, 226 can include at least one processor and a memory storing instructions to be executed by the at least one processor. In some implementations, the onboard computing systems 224, 226 can be a programmable logic device (PLD) such as a field-programmable gate array (FPGA).

As shown in FIG. 2, one onboard computing system 224 is positioned in the uphole portion 206 of the tool body 204, and one onboard computing system 226 is positioned in the downhole portion 208 of the tool body 204. The onboard computing system 224 can be configured to operate the one or more sensors 222 to measure a microbial concentration level or a hydrogen concentration or both in the wellbore. For example, the onboard computing system 224 can receive signals from and transmit signals to the one or more sensors 222. The onboard computing system 224 can process the received signals to determine the microbial concentration level or the hydrogen concentration. The onboard computing system 224 can transmit data representing the microbial concentration level or the hydrogen concentration to the onboard computing system 226.

The onboard computing system 226 can be configured to control the injection of the microbial inhibitor fluid into the subsurface formation. For example, the onboard computing system 226 can operate the injection pumps 220 and the injection nozzles 210 to inject the microbial inhibitor fluid into the subsurface formation. The onboard computing system 226 can control the injection quantities, the intervals (time and space) between injections, and injection pressure levels. The onboard computing system 226 can control the injections based on data received from the one or more sensors 222 (e.g., data transmitted by the onboard computing system 224). For example, in response to measuring a higher level of microbial concentration, the onboard computing system 226 can increase the quantity, the frequency, and/or the pressure levels of the injections to increase an amount of microbial inhibitor fluid injected into the subsurface formation. In some implementations, the onboard computing system 226 can determine a mixture of microbial inhibitor fluids to inject into the subsurface formation based on a detected type of microbe in the subsurface formation.

The onboard computing systems 224, 226 can communicate with each other through a wireless communications network (e.g., short range radio communications). Wireless communication avoids potential breaks that could occur in a wired connection due to the harsh environment of the wellbore. Wireless communication also does not require space for cables to be run from one onboard computing system to another onboard computing system. Since the distance between the onboard computing systems 224, 226 is limited by the size of the tool body 204, the wireless communications can be maintained between the two onboard computing systems within the wellbore.

One or more of the onboard computing systems 224, 226 can also be connected with a data processing system (e.g., computer or control system) located at the surface. The connection to the data processing system located at the surface is a wired communications link. In some implementations, only the computing system 224 that is located in the uphole portion 206 of the tool body 204 is connected with a wired network connection (e.g., through a wireline connector) with the data processing system at the surface. In such implementations, the onboard computing system 226 (and any additional onboard computing systems) can communicate with the data processing system at the surface through wireless communications with the onboard computing system 224.

In some implementations, the wireline tool 200 includes only one onboard computing system that can operate the sensors, control the microbial inhibitor fluid injections, and communicate with a data processing system at the surface. In some implementations, the wireline tool 200 does not include an onboard computing system. The wireline tool 200 is instead controlled by a data processing system located at the surface (e.g., in a control truck).

FIG. 3 is a schematic of a Clark-type hydrogen sensor 300 that can be used in the wireline tool 200 to measure hydrogen concentration in a subsurface formation. The Clark-type (or amperometric) hydrogen sensor 300 produces an electrical current as a function of the hydrogen concentration. The hydrogen sensor 300 includes an internal reference electrode 302 and a sensing anode 304. The hydrogen sensor 300 includes a high-sensitivity picoammeter 306. The sensing anode 304 is polarized against the internal reference electrode 302 by a voltage supply 308. The sensing anode 304 and the reference electrode 302 can be at least partially immersed in an electrolyte fluid 312 (e.g., potassium chloride, potassium bromide). The sensing anode 304 can include for example platinum, gold, and/or palladium. The reference electrode 302 can include, for example, silver and/or silver chloride.

Partial external gas pressure drives the sensing process by pressing the hydrogen through the tip sensor membrane 310. The hydrogen oxidizes at the surface of the sensing anode 304. The resulting oxidation current is measured by the picoammeter 306, which generates an electrical signal representing the measured current. The signal can be transmitted to an onboard computing system (e.g., onboard computing system 224).

The microbial concentration can be determined based on the hydrogen concentration. For example, the purity of the hydrogen concentration in the reservoir can be estimated based on the amount of injected hydrogen in the formation and the measured hydrogen concentration. If the hydrogen concentration decreases despite significant hydrogen injection, then this can indicate a decrease of the hydrogen purity and increased microbial concentration.

FIG. 4 is a flow chart for an example method 400 for injecting a microbial inhibitor into a subsurface formation. The method 400 can be implemented on a data processing system (e.g., onboard computing systems 224, 226).

The data processing system can measure a microbial concentration or a hydrogen concentration in a wellbore in a subsurface formation using one or more sensors of a downhole tool (step 402). Example measurements can include hydrogen concentration, pressure, temperature, and/or gas composition of gases in the wellbore. In some implementations, the data processing system determines the microbial concentration based on the measured hydrogen concentration. The data processing system can determine that the microbial concentration exceeds a threshold microbial concentration or that the hydrogen concentration falls below a threshold hydrogen concentration. The threshold microbial concentration or hydrogen concentration can be obtained from a user. For example, a degradation of 5% of the hydrogen concentration in the subsurface formation, as compared to the hydrogen concentration in the injected area can indicate that the microbial concentration has exceeded the threshold microbial concentration. Alternatively, or additionally, the threshold microbial concentration or threshold hydrogen concentration can be determined based on values of microbial concentration obtained from the subsurface formation (e.g., an average value, a median value, a maximum value, a minimum value).

The data processing system extends one or more nozzles from the downhole tool into the subsurface formation (step 404). For example, the data processing system operates a hydraulic system including one or more hydraulic actuators to extend the one or more nozzles into the subsurface formation.

The data processing system injects a microbial inhibitor into the subsurface formation by operating one or more injection pumps to pump the microbial inhibitor from the one or more tanks within the downhole tool through the one or more injection nozzles into the subsurface formation (step 406). For example, in response to determining that the microbial concentration exceeds the threshold microbial concentration or that the hydrogen concentration falls below the threshold hydrogen concentration the data processing system injects the microbial inhibitor. The data processing system can determine an amount, a rate, and/or a frequency to inject the microbial inhibitor into the subsurface formation based on the measurements from the one or more sensors.

FIG. 5 is a block diagram of an example computer system 500 used to provide computational functionalities associated with described algorithms, methods, functions, processes, flows, and procedures described in the present disclosure, according to some implementations of the present disclosure. The illustrated computer 502 is intended to encompass any computing device such as a server, a desktop computer, a laptop/notebook computer, a wireless data port, a smart phone, a personal data assistant (PDA), a tablet computing device, or one or more processors within these devices, including physical instances, virtual instances, or both. The computer 502 can include input devices such as keypads, keyboards, and touch screens that can accept user information. Also, the computer 502 can include output devices that can convey information associated with the operation of the computer 502. The information can include digital data, visual data, audio information, or a combination of information. The information can be presented in a graphical user interface (UI) (or GUI).

The computer 502 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 502 is communicably coupled with a network 530. In some implementations, one or more components of the computer 502 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 502 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 502 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 502 can receive requests over network 530 from a client application (for example, executing on another computer 502). The computer 502 can respond to the received requests by processing the received requests using software applications. Requests can also be sent to the computer 502 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 502 can communicate using a system bus 503. In some implementations, any or all of the components of the computer 502, including hardware or software components, can interface with each other or the interface 504 (or a combination of both), over the system bus 503. Interfaces can use an application programming interface (API) 512, a service layer 513, or a combination of the API 512 and service layer 513. The API 512 can include specifications for routines, data structures, and object classes. The API 512 can be either computer-language independent or dependent. The API 512 can refer to a complete interface, a single function, or a set of APIs.

The service layer 513 can provide software services to the computer 502 and other components (whether illustrated or not) that are communicably coupled to the computer 502. The functionality of the computer 502 can be accessible for all service consumers using this service layer. Software services, such as those provided by the service layer 513, 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 502, in alternative implementations, the API 512 or the service layer 513 can be stand-alone components in relation to other components of the computer 502 and other components communicably coupled to the computer 502. Moreover, any or all parts of the API 512 or the service layer 513 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 502 includes an interface 504. Although illustrated as a single interface 504 in FIG. 5, two or more interfaces 504 can be used according to particular needs, desires, or particular implementations of the computer 502 and the described functionality. The interface 504 can be used by the computer 502 for communicating with other systems that are connected to the network 530 (whether illustrated or not) in a distributed environment. Generally, the interface 504 can include, or be implemented using, logic encoded in software or hardware (or a combination of software and hardware) operable to communicate with the network 530. More specifically, the interface 504 can include software supporting one or more communication protocols associated with communications. As such, the network 530 or the interface's hardware can be operable to communicate physical signals within and outside of the illustrated computer 502.

The computer 502 includes a processor 505. Although illustrated as a single processor 505 in FIG. 5, two or more processors 505 can be used according to particular needs, desires, or particular implementations of the computer 502 and the described functionality. Generally, the processor 505 can execute instructions and can manipulate data to perform the operations of the computer 502, including operations using algorithms, methods, functions, processes, flows, and procedures as described in the present disclosure.

The computer 502 also includes a database 506 that can hold data for the computer 502 and other components connected to the network 530 (whether illustrated or not). For example, database 506 can hold data 516 (e.g., microbial concentration data, hydrogen quality data). For example, database 506 can be an in-memory, conventional, or a database storing data consistent with the present disclosure. In some implementations, database 506 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 502 and the described functionality. Although illustrated as a single database 506 in FIG. 5, two or more databases (of the same, different, or combination of types) can be used according to particular needs, desires, or particular implementations of the computer 502 and the described functionality. While database 506 is illustrated as an internal component of the computer 502, in alternative implementations, database 506 can be external to the computer 502.

The computer 502 also includes a memory 507 that can hold data for the computer 502 or a combination of components connected to the network 530 (whether illustrated or not). Memory 507 can store any data consistent with the present disclosure. In some implementations, memory 507 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 502 and the described functionality. Although illustrated as a single memory 507 in FIG. 5, two or more memories 507 (of the same, different, or combination of types) can be used according to particular needs, desires, or particular implementations of the computer 502 and the described functionality. While memory 507 is illustrated as an internal component of the computer 502, in alternative implementations, memory 507 can be external to the computer 502.

The application 508 can be an algorithmic software engine providing functionality according to particular needs, desires, or particular implementations of the computer 502 and the described functionality. For example, application 508 can serve as one or more components, modules, or applications. Further, although illustrated as a single application 508, the application 508 can be implemented as multiple applications 508 on the computer 502. In addition, although illustrated as internal to the computer 502, in alternative implementations, the application 508 can be external to the computer 502.

The computer 502 can also include a power supply 514. The power supply 514 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 514 can include power-conversion and management circuits, including recharging, standby, and power management functionalities. In some implementations, the power-supply 514 can include a power plug to allow the computer 502 to be plugged into a wall socket or a power source to, for example, power the computer 502 or recharge a rechargeable battery.

There can be any number of computers 502 associated with, or external to, a computer system containing computer 502, with each computer 502 communicating over network 530. 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 502 and one user can use multiple computers 502.

Implementations of the subject matter and the functional operations described in this specification can be implemented in digital electronic circuitry, in tangibly embodied computer software or firmware, in computer hardware, including the structures disclosed in this specification and their structural equivalents, or in combinations of one or more of them. Software implementations of the described subject matter can be implemented as one or more computer programs. Each computer program can include one or more modules of computer program instructions encoded on a tangible, non transitory, computer-readable computer-storage medium for execution by, or to control the operation of, data processing apparatus. Alternatively, or additionally, the program instructions can be encoded in/on an artificially generated propagated signal. The example, the signal can be a machine-generated electrical, optical, or electromagnetic signal that is generated to encode information for transmission to suitable receiver apparatus for execution by a data processing apparatus. The computer-storage medium can be a machine-readable storage device, a machine-readable storage substrate, a random or serial access memory device, or a combination of computer-storage mediums.

The terms “data processing apparatus,” “computer,” and “electronic computer device” (or equivalent as understood by one of ordinary skill in the art) refer to data processing hardware. For example, a data processing apparatus can encompass all kinds of apparatus, devices, and machines for processing data, including by way of example, a programmable processor, a computer, or multiple processors or computers. The apparatus can also include special purpose logic circuitry including, for example, a central processing unit (CPU), a field programmable gate array (FPGA), or an application specific integrated circuit (ASIC). In some implementations, the data processing apparatus or special purpose logic circuitry (or a combination of the data processing apparatus or special purpose logic circuitry) can be hardware- or software-based (or a combination of both hardware-and software-based). The apparatus can optionally include code that creates an execution environment for computer programs, for example, code that constitutes processor firmware, a protocol stack, a database management system, an operating system, or a combination of execution environments. The present disclosure contemplates the use of data processing apparatuses with or without conventional operating systems, for example LINUX, UNIX, WINDOWS, MAC OS, ANDROID, or IOS.

The methods, processes, or logic flows described in this specification can be performed by one or more programmable computers executing one or more computer programs to perform functions by operating on input data and generating output. The methods, processes, or logic flows can also be performed by, and apparatus can also be implemented as, special purpose logic circuitry, for example, a CPU, an FPGA, or an ASIC.

Computer readable media (transitory or non-transitory, as appropriate) suitable for storing computer program instructions and data can include all forms of permanent/non-permanent and volatile/non-volatile memory, media, and memory devices. Computer readable media can include, for example, semiconductor memory devices such as random access memory (RAM), read only memory (ROM), phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), and flash memory devices. Computer readable media can also include, for example, magnetic devices such as tape, cartridges, cassettes, and internal/removable disks.

While this specification contains many specific implementation details, these should not be construed as limitations on the scope of what may be claimed, but rather as descriptions of features that may be specific to particular implementations. Certain features that are described in this specification in the context of separate implementations can also be implemented, in combination, in a single implementation. Conversely, various features that are described in the context of a single implementation can also be implemented in multiple implementations, separately, or in any suitable sub-combination. Moreover, although previously described features may be described as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can, in some cases, be excised from the combination, and the claimed combination may be directed to a sub-combination or variation of a sub-combination.

Particular implementations of the subject matter have been described. Other implementations, alterations, and permutations of the described implementations are within the scope of the following claims as will be apparent to those skilled in the art. While operations are depicted in the drawings or claims in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed (some operations may be considered optional), to achieve desirable results. In certain circumstances, multitasking or parallel processing (or a combination of multitasking and parallel processing) may be advantageous and performed as deemed appropriate.

Moreover, the separation or integration of various system modules and components in the previously described implementations should not be understood as requiring such separation or integration in all implementations, and it should be understood that the described program components and systems can generally be integrated together in a single software product or packaged into multiple software products.

Accordingly, the previously described example implementations do not define or constrain the present disclosure. Other changes, substitutions, and alterations are also possible without departing from the spirit and scope of the present disclosure.

Furthermore, any claimed implementation is considered to be applicable to at least a computer-implemented method; a non-transitory, computer-readable medium storing computer-readable instructions to perform the computer-implemented method; and a computer system comprising a computer memory interoperably coupled with a hardware processor configured to perform the computer-implemented method or the instructions stored on the non-transitory, computer-readable medium.

A number of implementations of these systems and methods have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of this disclosure. Accordingly, other implementations are within the scope of the following claims.

EXAMPLES

In an example implementation, a downhole tool for injecting a microbial inhibitor into a subsurface formation includes a tool body; one or more tanks disposed within the tool body, the one or more tanks configured to contain a microbial inhibitor fluid; one or more injection nozzles fluidly connected to the one or more tanks, the one or more injection nozzles extending from an outer surface of the tool body; one or more injection pumps fluidly coupled to the one or more tanks and operable to pump the microbial inhibitor fluid from the one or more tanks through the one or more injection nozzles; one or more sensors configured to measure a microbial concentration, a hydrogen concentration, or both; and an onboard computer system disposed within the tool body configured to operate the one or more injection pumps and the one or more injection nozzles to inject the microbial inhibitor fluid into a subsurface formation in response to measurements from the one or more sensors.

In an aspect combinable with the example implementation, the one or more injection nozzles include sharp tips to penetrate the subsurface formation to inject the microbial inhibitor fluid directly into the subsurface formation.

In another aspect combinable with any of the previous aspects, the one or more injection nozzles are attached to one or more hydraulic actuators, the one or more hydraulic actuators operable to move the one or more injection nozzles from a retracted position to an extended position to insert the one or more injection nozzles into the subsurface formation.

In another aspect combinable with any of the previous aspects, the one or more sensors include a Clark-type hydrogen sensor including an internal reference electrode and a sensing anode.

In another aspect combinable with any of the previous aspects, the Clark-type hydrogen sensor is electrically coupled with a picoammeter to measure an oxidation current.

In another aspect combinable with any of the previous aspects, the onboard computer system is a first onboard computer system, and the downhole tool further includes a second onboard computer system configured to operate the one or more sensors to determine a microbial concentration level, where the tool body includes a downhole portion and an uphole portion, the downhole portion including the one or more tanks, the one or more injection pumps, and the first onboard computer system, and the uphole portion including the one or more sensors, and the second onboard computer system, and where the first onboard computer system and the second onboard computer system are configured to communicate over a wireless communications network.

In another aspect combinable with any of the previous aspects, the one or more injection pumps include pressure piston pumps.

In another aspect combinable with any of the previous aspects, the onboard computer system is further configured to determine an amount, a rate, and a frequency to inject the microbial inhibitor fluid into the subsurface formation based on the measurements from the one or more sensors.

In another aspect combinable with any of the previous aspects, the one or more sensors extend from the outer surface of the tool body toward walls of a wellbore.

In another example implementation, a method for operating a downhole tool to inject a microbial inhibitor in a subsurface formation includes extending one or more injection nozzles from the downhole tool into the subsurface formation; and injecting a microbial inhibitor into the subsurface formation by operating one or more injection pumps to pump the microbial inhibitor from one or more tanks within the downhole tool through the one or more injection nozzles into the subsurface formation.

An aspect combinable with the example implementation includes measuring a microbial concentration or a hydrogen concentration in a wellbore of the subsurface formation using one or more sensors of the downhole tool.

Another aspect combinable with any of the previous aspects includes in response to determining that the microbial concentration exceeds a threshold microbial concentration or determining that the hydrogen concentration falls below a threshold hydrogen concentration, injecting the microbial inhibitor into the subsurface formation.

Another aspect combinable with any of the previous aspects includes determining an amount, a rate, and a frequency to inject the microbial inhibitor into the subsurface formation based on measurements from the one or more sensors.

In another aspect combinable with any of the previous aspects, the one or more sensors include a Clark-type hydrogen sensor including an internal reference electrode; a sensing anode; and a picoammeter electrically coupled to the internal reference electrode and the sensing anode and operable to measure an oxidation current.

In another aspect combinable with any of the previous aspects, extending the one or more injection nozzles includes operating a hydraulic system coupled to the one or more injection nozzles to extend the one or more injection nozzles from a retracted position near an outer surface of the downhole tool to an extended position away from the outer surface of the downhole tool to insert the one or more injection nozzles into the subsurface formation.

In another aspect combinable with any of the previous aspects, the one or more injection pumps comprise pressure piston pumps.

In another example implementation, a downhole tool for injecting a microbial inhibitor into a subsurface formation includes a tool body; a tank disposed within the tool body configured to contain a microbial inhibitor fluid; an injection nozzle fluidly connected to the tank, the injection nozzle extending from an outer surface of the tool body; an injection pump fluidly coupled to the tank and operable to pump the microbial inhibitor fluid from the tank through the injection nozzle; and a sensor operable to measure a microbial concentration, a hydrogen concentration, or both.

An aspect combinable with the example implementation includes a first onboard computer system configured to control the injection pump and the injection nozzle to inject the microbial inhibitor fluid into a subsurface formation; and a second onboard computer system configured to operate the sensor to determine a microbial concentration level, a hydrogen concentration, or both.

In another aspect combinable with any of the previous aspects, the first onboard computer system and the second onboard computer system each include a field programmable gated array.

In another aspect combinable with any of the previous aspects, the injection nozzle is attached to a hydraulic actuator, the hydraulic actuator operable to move the injection nozzle from a retracted position to an extended position to insert the injection nozzle into the subsurface formation.