Downhole pumping tools

Methods, systems, and computer-readable medium to perform operations including: determining, based on at least one dimension of an annulus of a wellbore, a respective downhole position at which to position at least one of an upper sensor and a lower sensor of a downhole pumping tool that includes a pump; positioning the downhole pumping tool in the wellbore such that at least one of the upper sensor and the lower sensor are positioned at the respective downhole position; in response to the upper sensor detecting a first fluid level in the annulus, activating the pump so that the pump pumps fluid from the annulus into a tubing of the wellbore, where the tubing carries the fluid to the surface; and in response to the lower sensor detecting a second fluid level in the annulus, deactivating the pump, where the second fluid level is below the first fluid level.

TECHNICAL FIELD

This description relates to downhole pumping tools.

BACKGROUND

The productivity index of a reservoir is a measure of the reservoir's potential or ability to produce hydrocarbons. A reservoir that has a low productivity index has low production potential or ability to produce hydrocarbons.

SUMMARY

In low productivity index reservoirs, fluids (for example, hydrocarbon fluids) take time to accumulate within wellbores. As result, in practice, pumps are not used in wellbores located in low productivity index reservoirs since pumps are susceptible to burning, for example, in scenarios where the fluid level is too low to be pumped. Instead, sucker rod or plunger lift technologies are used in these wellbores since such mechanical devices are not susceptible to burning. However, sucker rod or plunger lift technologies have depth limitations, and thus, cannot be used in wellbores that extend beyond a certain depth. Wellbores that extend beyond the depth limitations of sucker rod or plunger lift technologies are increasingly being used in practice. Therefore, an alternative for sucker rod or plunger lift technologies, particularly in low productivity index reservoirs, is desired.

This disclosure describes tools that enable using pumps, such as electrical submersible pumps, in low productivity index reservoirs. The tools can be deployed, for example, downhole in wellbores located in low productivity index reservoirs. In an embodiment, a downhole pumping tool includes a first packer, a second packer, a pump, a first sensor, and a second sensor. The first packer, the second packer, and a tubing of the wellbore form an annulus when engaged with a downhole casing of the wellbore. The pump defines an inlet from the annulus into the tubing, which can carry fluids to the surface. The first sensor and the second sensor are located along a side of the tubing and are longitudinally separated such that the first sensor is closer to the first packer than the second sensor, and the second sensor is closer to the pump than the first sensor. The first sensor is configured to activate the pump when fluid in the annulus reaches a first fluid level. The second sensor is configured to deactivate the pump when the fluid reaches a second fluid level that is below the first fluid level.

Aspects of the subject matter described in this specification may be embodied in methods that include the actions of: determining, based on at least one dimension of an annulus of a wellbore, a respective downhole position at which to position at least one of an upper sensor and a lower sensor of a downhole pumping tool that includes a pump; positioning the downhole pumping tool in the wellbore such that at least one of the upper sensor and the lower sensor are positioned at the respective downhole position; in response to the upper sensor detecting a first fluid level in the annulus, activating the pump so that the pump pumps fluid from the annulus into a tubing of the wellbore, where the tubing carries the fluid to the surface; and in response to the lower sensor detecting a second fluid level in the annulus, deactivating the pump, where the second fluid level is below the first fluid level.

The previously-described implementation is applicable using a computer-implemented method; a non-transitory, computer-readable medium storing computer-readable instructions to perform the computer-implemented method; and a computer system including 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. These and other embodiments may each optionally include one or more of the following features.

In some implementations, the actions further including affixing a first packer to a first outer surface of the tubing and a casing of the wellbore, where the first packer longitudinally closer to the first sensor than the second sensor; and affixing a second packer to a second outer surface of the tubing and the casing, where the first and second outer surfaces are on horizontally opposite sides of the tubing, and where the tubing, the first packer, the second packer form the annulus when engaged with the casing.

In some implementations, the upper and lower sensors are located between a first plurality of perforations in the casing and the first packer.

In some implementations, the first packer and the second packer are inflatable packers.

In some implementations, the tubing is a production string.

In some implementations, the downhole pumping tool further includes: a porous housing defining an inner volume; and a floatable object that floats on the fluid, wherein the floatable object, the first sensor, and the second sensor are located within the inner volume, and wherein the first sensor and the second sensor are configured to detect the floatable object.

In some implementations, the pump is an electric submersible pump.

The subject matter described in this specification can be implemented in particular implementations so as to realize one or more of the following advantages. The disclosed tools enable using pumps, such as electrical submersible pumps, in low productivity index reservoirs. In particular, the tools significantly reduce or eliminate the risk of pumps burning out, for example, in low productivity index reservoirs. Using the disclosed tools improves drilling operations and facilitates hydrocarbon exploration in formations that existing tools are not capable of exploring.

DETAILED DESCRIPTION

The present disclosure describes a downhole pumping tool that is operable to pump a fluid from a subterranean zone to the surface. The tool includes tubular conduits affixed to each other and positioned in a wellbore. Further, the tool includes wellbore seals that help form an annulus in the wellbore. Hydrocarbon fluid from the subterranean zone collects in the annulus. When the hydrocarbon fluid level reaches a first predefined level, a pump pumps the hydrocarbon fluid from the annulus into the tubular conduit. Then, when the hydrocarbon fluid level falls to a second predefined level, the pumps stops pumping the hydrocarbon fluid. By operating as such, the tool avoids scenarios where the fluid level is too low to pump, which can result in the pump burning.

FIG.1is a schematic illustration of an example wellbore system100that includes a downhole pumping tool102, according to some implementations. More specifically,FIG.1illustrates the downhole pumping tool102disposed in a wellbore located in a formation104. In this arrangement, the downhole pumping tool102receives a hydrocarbon fluid (for example, oil) from the formation104through perforations116in a casing118of the wellbore. The downhole pumping tool102directs the flow of the hydrocarbon fluid into an annulus formed in the wellbore system100. The hydrocarbon fluid then accumulates in the annulus.

In an embodiment, the wellbore system100includes a downhole conveyance that is operable to convey (for example, run in) the downhole pumping tool102into the wellbore. Although not shown, a drilling assembly deployed on the surface may form the wellbore prior to running the downhole pumping tool102into the wellbore. In some embodiments, the wellbore system100extends from the surface and through one or more geological formations in the Earth including the formation104. The formation104includes a hydrocarbon fluid zone and is located under the surface. As explained in more detail below, one or more wellbore casings, such as the casing118, can be installed in at least a portion of the wellbore.

In some embodiments, the wellbore system100is deployed on a body of water rather than a terranean surface. In these embodiments, the surface may be an ocean, gulf, sea, or any other body of water under which hydrocarbon-bearing formations can be found. In short, reference to “a surface” includes both land and water surfaces and contemplates forming and developing one or more wellbore systems100from either or both locations.

In some embodiments, the downhole conveyance includes a tubular production string made up of multiple tubing joints. As an example, a tubular production string (also known as a production casing) includes sections of steel pipe, which are threaded so that they can interlock together. As shown inFIG.1, the wellbore system100includes tubing106. As another example, the downhole conveyance includes coiled tubing. As yet another example, a wireline or slickline conveyance (not shown) is communicably coupled to the downhole pumping tool102.

In some embodiments, the wellbore is cased with one or more casings such as casing118. In some examples, the wellbore is from vertical (for example, a slant wellbore). In other examples, the wellbore is a stepped wellbore, such that a portion is drilled vertically downward and then curved to a substantially horizontal wellbore portion. Additional substantially vertical and horizontal wellbore portions can be added according to, for example, the type of surface, the depth of one or more target subterranean formations, the depth of one or more productive subterranean formations, or other criteria. As shown inFIG.1, the casing118includes perforations116through which hydrocarbon fluid flows from the formation104into an annulus120.

In some embodiments, the downhole pumping tool102includes an electric submersible pump (ESP)110, an upper sensor112a, a lower sensor112b, a first seal108a, and a second seal108b. The tubing106includes a lower vertical opening in which the ESP110is disposed. The first seal108aand the second seal108bare configured to form a seal between the tubing106and the casing118. As shown inFIG.1, the first seal108ais affixed to a first outer surface of the tubing106and the second seal108bis affixed to a second outer surface of the tubing106, where the first and the second outer surfaces are on horizontally opposite sides of the tubing106. In some implementations, the first seal108aand the second seal108bare packers, for example, inflatable packers or mechanical packers. When sealed, the first seal108a, the second seal108b, the tubing106, and the casing118form the annulus120that functions as a receptacle for hydrocarbon fluids.

The ESP110includes an inlet that faces a bottom surface of the annulus120and includes an outlet into the tubing106. Thus, the ESP110forms a passage for hydrocarbon fluids to flow from the annulus120into the tubing106(and then to the surface). For example, the ESP110injects hydrocarbon fluids from the annulus120into the tubing106. The ESP110is controlled based on a hydrocarbon fluid level in the annulus. More specifically, the upper sensor112aand the lower sensor112bdetect the hydrocarbon fluid level and turn the ESP110on or off based on detected level. Within examples, the upper sensor112aand the lower sensor112bcan be an image sensors, optical sensors, time-of-flight sensors, motion detectors, fluid level sensors, electromagnetic sensors, tactile sensors, or proximity sensors.

As shown inFIG.1, the upper sensor112ais located closer to the seal first108athan the lower sensor112b, and the lower sensor112bis located closer to the ESP110than the upper sensor112a. In an example arrangement, the upper sensor112aand the lower sensor112bare positioned on an outer surface of the tubing106. In another example, the upper sensor112aand the lower sensor112bare positioned near the outer surface of the tubing106, for example, on a standalone structure. The standalone structure can include movable platforms on which the upper sensor112aand the lower sensor112bare installed. The position of the movable platforms can be adjusted in order to adjust the positions of the upper sensors112aand the lower sensor112b. In yet another example, the upper sensor112aand the lower sensor112bare disposed within a porous housing (for example, a side-perforated housing). The porous housing defines an inner volume in which the upper sensor112aand the lower sensor112bare disposed. In some examples, the porous housing is a side-perforated pocket or housing122that houses the sensors112a,112band the floating object114.

In some embodiments, the upper sensor112ais configured to turn on the ESP110when the fluid level in the annulus reaches a level at which the upper sensor112ais installed. This operation ensures that the ESP110is operated only when there is sufficient hydrocarbon fluid in the annulus to be pumped. The lower sensor112bis configured to turn off the ESP110when the fluid level in the annulus falls to a level at which the lower sensor112bis installed. This operation ensures that the ESP110is turned off when the fluid level falls below a level at which the ESP110cannot pump the fluid without risk of burning.

In some embodiments, an object114that can float on the hydrocarbon fluid is disposed in the annulus. The object114is also referred to as a floating object or a floatable object. In these embodiments, the upper sensor112aand the lower sensor112bdetect the fluid level when the floating object114, which floats on the surface of the fluid, is detected by the upper sensor112aor the lower sensor112b. When the upper sensor112adetects the floating object, the upper sensor112asignals the ESP110to turn on. And when the lower sensor112bdetects the floating object, the lower sensor112bsignals the ESP110to turn off.

FIG.2AandFIG.2Bare schematic illustrations of an example downhole pumping tool in operation, according to some implementations. Specifically,FIG.2Aillustrates a scenario200in which the ESP110is turned on andFIG.2Billustrates a scenario210in which the ESP110is turned off. As shown inFIG.2A, a fluid level in the annulus120has reached a level at which the upper sensor112ais located. The upper sensor112adetermines that the fluid level has reached a first predetermined level by either detecting the surface of the fluid or by detecting the floating object114. In response to the determination, the upper sensor112asends signals the ESP110to turn on. The ESP110turns on and pumps fluid from the annulus120into the tubing106. Turning toFIG.2B, after the ESP110pumps the fluid into the tubing106, the fluid level in the annulus120begins to drop. As shown inFIG.2B, the fluid level in the annulus120has reached a level at which the lower sensor112bis located. The upper sensor112adetermines that the fluid level has reached a second predetermined level predetermined level by either detecting the surface of the fluid or by detecting the floating object114. Once the lower sensor112bdetermines that the fluid level in the annulus120has dropped to the second predetermined level, the lower sensor112bsignals the ESP110to turn off. As a result, the ESP110stops pumping fluid into the tubing106.

FIG.3illustrates a flowchart of an example method300, according to some implementations. For clarity of presentation, the description that follows generally describes the method300in the context of the other figures in this description. For example, the method300can be performed by the computing system400shown inFIG.4. However, it will be understood that the method300can be performed, for example, by any suitable system, environment, software, and hardware, or a combination of systems, environments, software, and hardware, as appropriate. In some implementations, various steps of the method300can be run in parallel, in combination, in loops, or in any order.

At step302, the method300involves determining, based on at least one dimension of an annulus of a wellbore, a respective downhole position at which to position at least one of an upper sensor and a lower sensor of a downhole pumping tool that includes a pump. In an example, the at least one dimension of the annulus is used to determine a volume of the annulus, which, in turn, is used to determine an amount of fluid that can be stored in the annulus. Since the position of the upper sensor determines the fluid level at which the pump is turned on, the position of the upper sensor determines the amount of fluid in the annulus when the pump is turned on. Similarly, since the position of the lower sensor determines the fluid level at which the pump is turned off, the position of the lower sensor determines the amount of fluid in the annulus when the pump is turned off. The position of the lower sensor can be determined such that the amount of fluid that is in annulus when the pump is turned off is greater than a minimum amount of fluid that the pump needs to operate without burning. The minimum amount of fluid can be determined, for example, based on specifications of the pump.

In another example, the at least one dimension of the annulus is used to determine a distance between the upper sensor and the lower sensor. In this example, the distance is a function of at least one of a height of the annulus and a flow rate of fluid into the annulus. For instance, the lower the flow rate of fluid into the annulus the greater the distance between the upper sensor and the lower sensor in order to avoid frequently switching the pump on/off.

At step304, the method300involves positioning the downhole pumping tool in the wellbore such that at least one of the upper sensor and the lower sensor are positioned at the respective downhole position. In an example, a downhole conveyance is used to position the downhole pumping tool in the wellbore. In particular, a computing system can control the downhole conveyance to position the downhole pumping tool such that the upper sensor and the lower sensor are disposed at the respective positions determined in step302.

At step306, the method300involves in response to the upper sensor detecting a first fluid level in the annulus, activating the pump so that the pump pumps fluid from the annulus into a tubing of the wellbore, where the tubing carries the fluid to the surface. At step308, the method300involves in response to the lower sensor detecting a second fluid level in the annulus, deactivating the pump, where the second fluid level is below the first fluid level.

In some implementations, the method300further includes affixing a first packer to a first outer surface of the tubing and a casing of the wellbore, where the first packer longitudinally closer to the first sensor than the second sensor; and affixing a second packer to a second outer surface of the tubing and the casing, where the first and second outer surfaces are on horizontally opposite sides of the tubing, and where the tubing, the first packer, the second packer form the annulus when engaged with the casing. In some implementations, affixing the packers involves a computing device or a human operator controlling a robotic device or a downhole conveyance to affix the packers to the outer surface of the tubing and the casing of the wellbore.

In some implementations, the upper and lower sensors are located between a first plurality of perforations in the casing and the first packer.

In some implementations, the first packer and the second packer are inflatable packers.

In some implementations, the tubing is a production string.

In some implementations, the downhole pumping tool further includes: a porous housing defining an inner volume; and a floatable object that floats on the fluid, wherein the floatable object, the first sensor, and the second sensor are located within the inner volume, and wherein the first sensor and the second sensor are configured to detect the floatable object.

In some implementations, the pump is an electric submersible pump.

FIG.4is a block diagram of an example computer system400that can be 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. In some implementations, a controller of the wellbore system100or the downhole pumping tool can be the computer system400or include the computer system400. In some implementations, the controller can communicate with the computer system400.

The illustrated computer402is intended to encompass any computing device such as a server, a desktop computer, an embedded 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 computer402can include input devices such as keypads, keyboards, and touch screens that can accept user information. Also, the computer402can include output devices that can convey information associated with the operation of the computer402. 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). In some implementations, the inputs and outputs include display ports (such as DVI-I+2x display ports), USB 3.0, GbE ports, isolated DI/O, SATA-III (6.0 Gb/s) ports, mPCIe slots, a combination of these, or other ports. In instances of an edge gateway, the computer402can include a Smart Embedded Management Agent (SEMA), such as a built-in ADLINK SEMA 2.2, and a video sync technology, such as Quick Sync Video technology supported by ADLINK MSDK+. In some examples, the computer402can include the MXE-5400 Series processor-based fanless embedded computer by ADLINK, though the computer402can take other forms or include other components.

The computer402can 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 computer402is communicably coupled with a network430. In some implementations, one or more components of the computer402can be configured to operate within different environments, including cloud-computing-based environments, local environments, global environments, and combinations of environments.

The computer402can receive requests over network430from a client application (for example, executing on another computer402). The computer402can respond to the received requests by processing the received requests using software applications. Requests can also be sent to the computer402from 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 computer402can communicate using a system bus. In some implementations, any or all of the components of the computer402, including hardware or software components, can interface with each other or the interface404(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 API and service layer. The API can include specifications for routines, data structures, and object classes. The API can be either computer-language independent or dependent. The API can refer to a complete interface, a single function, or a set of APIs.

The service layer can provide software services to the computer402and other components (whether illustrated or not) that are communicably coupled to the computer402. The functionality of the computer402can 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 computer402, in alternative implementations, the API or the service layer can be stand-alone components in relation to other components of the computer402and other components communicably coupled to the computer402. Moreover, any or all parts of the API or the service layer 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 computer402can include an interface404. Although illustrated as a single interface404inFIG.4, two or more interfaces404can be used according to particular needs, desires, or particular implementations of the computer402and the described functionality. The interface404can be used by the computer402for communicating with other systems that are connected to the network430(whether illustrated or not) in a distributed environment. Generally, the interface404can include, or be implemented using, logic encoded in software or hardware (or a combination of software and hardware) operable to communicate with the network430. More specifically, the interface404can include software supporting one or more communication protocols associated with communications. As such, the network430or the interface's hardware can be operable to communicate physical signals within and outside of the illustrated computer402.

The computer402includes a processor405. Although illustrated as a single processor405inFIG.4, two or more processors405can be used according to particular needs, desires, or particular implementations of the computer402and the described functionality. Generally, the processor405can execute instructions and can manipulate data to perform the operations of the computer402, including operations using algorithms, methods, functions, processes, flows, and procedures as described in the present disclosure.

The computer402can also include a database406that can hold data for the computer402and other components connected to the network430(whether illustrated or not). For example, database406can be an in-memory, conventional, or a database storing data consistent with the present disclosure. In some implementations, database406can 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 computer402and the described functionality. Although illustrated as a single database406inFIG.4, 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 computer402and the described functionality. While database406is illustrated as an internal component of the computer402, in alternative implementations, database406can be external to the computer402.

The computer402also includes a memory407that can hold data for the computer402or a combination of components connected to the network430(whether illustrated or not). Memory407can store any data consistent with the present disclosure. In some implementations, memory407can 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 computer402and the described functionality. Although illustrated as a single memory407inFIG.4, two or more memories407(of the same, different, or combination of types) can be used according to particular needs, desires, or particular implementations of the computer402and the described functionality. While memory407is illustrated as an internal component of the computer402, in alternative implementations, memory407can be external to the computer402.

An application can be an algorithmic software engine providing functionality according to particular needs, desires, or particular implementations of the computer402and the described functionality. For example, an application can serve as one or more components, modules, or applications. Multiple applications can be implemented on the computer402. Each application can be internal or external to the computer402.

The computer402can also include a power supply414. The power supply414can include a rechargeable or non-rechargeable battery that can be configured to be either user- or non-user-replaceable. In some implementations, the power supply414can include power-conversion and management circuits, including recharging, standby, and power management functionalities. In some implementations, the power-supply414can include a power plug to allow the computer402to be plugged into a wall socket or a power source to, for example, power the computer402or recharge a rechargeable battery.

There can be any number of computers402associated with, or external to, a computer system including computer402, with each computer402communicating over network430. 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 computer402and one user can use multiple computers402.