Inhibiting Microbial Activity in a Subsurface Formation

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

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.

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.

is a schematic illustrating a subsurface formation.

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

is a schematic illustrating a Clark-type hydrogen sensor.

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

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.

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.

illustrates a wireline operationusing a wireline toolto inject microbial inhibitor into a subsurface formation. A wellboreextends downhole from a wellhead. The wellboreis a vertical wellbore but wireline operations can also be performed in other wellbores, for example, slanted or horizontal wellbores. In the wireline operation, the wellborepenetrates through five layers,,,,of a subsurface formation. A control trucklowers the wireline tooldown the wellboreon a wireline. The subsurface formationcan include one or more locations to store hydrogen gas within the subsurface formation (e.g., a depleted gas or oil reservoir)

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

The wireline toolcan be a part of a string of multiple instruments with sensors operable to measure properties of the subsurface formation. 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.

is a schematic of the downhole wireline toolfor injecting microbial inhibitor into a subsurface formation. The wireline toolcan be used in a wireline operation (e.g., wireline operation). The wireline toolis shown within a wellborethat has been drilled into a subsurface formation. The wireline toolincludes microbial inhibitor fluid to be injected into the subsurface formation through injection nozzles. For example, the wireline toolcan 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 toolincludes a tool bodyincluding two tanksto hold microbial inhibitor fluid. The wireline toolinclude injection pumpsto pump fluid from the tanksinto the subsurface formation through the injection nozzles. The wireline toolincludes onboard computing systems,to obtain measurements from the subsurface formation and to control the wireline tool.

The tool bodyincludes an uphole portionand a downhole portion. The uphole portionincludes sensorsand the onboard computing system. The downhole portionincludes the tanksand onboard computing system. The tool bodycan be made from steel, for example. The tool body protects internal components of the wireline toolform harsh conditions that can exist in a wellbore. In some implementations, the uphole portionand the downhole portionare separate modules (e.g., a sensing module and an injection module) that are assembled to form the downhole tool.

The tool bodytwo tanksthat can hold a microbial inhibitor fluid to be injected into the subsurface formation. The tankscan hold the same microbial inhibitor fluid or each tankcan 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 tankscan 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 toolincludes a single tank. In some implementations, the wireline toolincludes 3 or more tanks. The number of tanks included in the wireline toolcan 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 toolcan 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 tooland through the injection nozzles.

The injection nozzlesextend from an outer surfaceof the tool body. The injection nozzlesare fluidly coupled to the tanks. The injection nozzlescan have sharp tipsat distal ends of the injection nozzles to facilitate penetration of the injection nozzlesinto the subsurface formation. The tipscan be made of, for example, titanium. The sharpness of the tipscan be based on the aspect ratio of the tip(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 actuatorsattached to the injection nozzlesare operative to extend the injection nozzlesfrom a retracted position near the outer surfaceof the tool bodyto an extended position away from the outer surfaceof the tool bodyand into the subsurface formation. The hydraulic actuatorscan retract the injection nozzlesfrom the extended position to the retracted position. The hydraulic actuatorscan provide sufficient force to the injection nozzlesto 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 nozzlesinto 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 nozzlescan 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 pumpsare coupled to the tanks. The injection pumpsare operable to pump the microbial inhibitor fluid from the tanksthrough the injection nozzlesinto the subsurface formation. The injection pumpscan be, for example, pressure piston pumps that can adjust the force applied by the injection pumpto the tanksto control the amount of microbial inhibitor fluid injected into the subsurface formation.

The wireline toolincludes one or more sensorsto measure a microbial concentration, a hydrogen concentration or both. The sensorscan extend from the outer surfaceof the tool bodytoward the walls of the wellbore. The sensorscan be pushed against the walls of the wellboreto measure the microbial concentration around the formation. The sensorscan be positioned in the uphole portionof the tool body. In an example, the wireline toolincludes four microbial sensors that each have a total length of 150-200 mm. The tip of the injection nozzlesis small in comparison with the sensors. For example, the sensorscan 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 sensorscan be Clark-type hydrogen sensors (see).

The wireline toolincludes onboard computing systems,. Each of the onboard computing systems,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,can be a programmable logic device (PLD) such as a field-programmable gate array (FPGA).

As shown in, one onboard computing systemis positioned in the uphole portionof the tool body, and one onboard computing systemis positioned in the downhole portionof the tool body. The onboard computing systemcan be configured to operate the one or more sensorsto measure a microbial concentration level or a hydrogen concentration or both in the wellbore. For example, the onboard computing systemcan receive signals from and transmit signals to the one or more sensors. The onboard computing systemcan process the received signals to determine the microbial concentration level or the hydrogen concentration. The onboard computing systemcan transmit data representing the microbial concentration level or the hydrogen concentration to the onboard computing system.

The onboard computing systemcan be configured to control the injection of the microbial inhibitor fluid into the subsurface formation. For example, the onboard computing systemcan operate the injection pumpsand the injection nozzlesto inject the microbial inhibitor fluid into the subsurface formation. The onboard computing systemcan control the injection quantities, the intervals (time and space) between injections, and injection pressure levels. The onboard computing systemcan control the injections based on data received from the one or more sensors(e.g., data transmitted by the onboard computing system). For example, in response to measuring a higher level of microbial concentration, the onboard computing systemcan 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 systemcan 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,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,is limited by the size of the tool body, the wireless communications can be maintained between the two onboard computing systems within the wellbore.

One or more of the onboard computing systems,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 systemthat is located in the uphole portionof the tool bodyis 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(and any additional onboard computing systems) can communicate with the data processing system at the surface through wireless communications with the onboard computing system.

In some implementations, the wireline toolincludes 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 tooldoes not include an onboard computing system. The wireline toolis instead controlled by a data processing system located at the surface (e.g., in a control truck).

is a schematic of a Clark-type hydrogen sensorthat can be used in the wireline toolto measure hydrogen concentration in a subsurface formation. The Clark-type (or amperometric) hydrogen sensorproduces an electrical current as a function of the hydrogen concentration. The hydrogen sensorincludes an internal reference electrodeand a sensing anode. The hydrogen sensorincludes a high-sensitivity picoammeter. The sensing anodeis polarized against the internal reference electrodeby a voltage supply. The sensing anodeand the reference electrodecan be at least partially immersed in an electrolyte fluid(e.g., potassium chloride, potassium bromide). The sensing anodecan include for example platinum, gold, and/or palladium. The reference electrodecan 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. The hydrogen oxidizes at the surface of the sensing anode. The resulting oxidation current is measured by the picoammeter, which generates an electrical signal representing the measured current. The signal can be transmitted to an onboard computing system (e.g., onboard computing system).

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.

is a flow chart for an example methodfor injecting a microbial inhibitor into a subsurface formation. The methodcan be implemented on a data processing system (e.g., onboard computing systems,).

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). 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). 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). 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.

is a block diagram of an example computer systemused 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 computeris 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 computercan include input devices such as keypads, keyboards, and touch screens that can accept user information. Also, the computercan include output devices that can convey information associated with the operation of the computer. 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 computercan 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 computeris communicably coupled with a network. In some implementations, one or more components of the computercan 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 computeris 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 computercan 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 computercan receive requests over networkfrom a client application (for example, executing on another computer). The computercan respond to the received requests by processing the received requests using software applications. Requests can also be sent to the computerfrom 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 computercan communicate using a system bus. In some implementations, any or all of the components of the computer, including hardware or software components, can interface with each other or the interface(or a combination of both), over the system bus. Interfaces can use an application programming interface (API), a service layer, or a combination of the APIand service layer. The APIcan include specifications for routines, data structures, and object classes. The APIcan be either computer-language independent or dependent. The APIcan refer to a complete interface, a single function, or a set of APIs.

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