Patent Publication Number: US-9410419-B2

Title: Device for measuring and transmitting downhole tension

Description:
BACKGROUND 
     The present disclosure relates to downhole measurements and, more particularly, to measuring the tension on a conveyance line with a downhole device. 
     After drilling and completing a wellbore that traverses a hydrocarbon-bearing formation, a tool string may be deployed down the wellbore to perform further operations on the wellbore. The tool string may be deployed using any number of conventional deployment methods, such as wireline or slickline deployment. The tool string may include a number of downhole tools and may additionally include equipment for monitoring conditions downhole. One example of a post-completion downhole tool that may be used is a perforating assembly, used in preparation for fracking and/or production operations. Upon conveyance of the tool downhole, one or more perforating guns associated with the perforating assembly are triggered to perforate the walls of the casing and wellbore and allow extraction of hydrocarbons from surrounding subterranean formations. 
     A telemetry cartridge is typically also included in tool strings and configured to communicate downhole information to the well operator at the surface. A casing collar locator (CCL) may optionally be attached to the telemetry cartridge. The CCL proves useful by passively detecting casing collars as the tool string is deployed or retrieved from the wellbore, thus resulting in providing the well operator with real-time depth information for the tool string. However, the CCL may not have sufficient signal to work in all ranges of casing sizes. The telemetry cartridge may also include tension measurement sensors to measure tension on the conveyance line. This tension information is important to the well operator as the conveyance line is typically connected to the downhole tool via a socket designed to separate the conveyance from the tool string upon experiencing a predetermined tensile load. Thus, the tension information may help the well operator prevent an unintentional disconnect of the tool string from the conveyance. 
     Unfortunately, operation of certain downhole tools, such as perforating guns, create violent disturbances which can damage the telemetry equipment and require repair or replacement of such equipment. Due to the potential for damaging telemetry equipment while using perforating equipment downhole, the telemetry cartridge and its associated sensors are often omitted from the tool string, thus depriving the well operator of valuable downhole information. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The following figures are included to illustrate certain aspects of the present disclosure, and should not be viewed as exclusive embodiments. The subject matter disclosed is capable of considerable modifications, alterations, combinations, and equivalents in form and function, without departing from the scope of this disclosure. 
         FIG. 1  is a well system that may embody or otherwise employ one or more principles of the present disclosure, according to one or more embodiments. 
         FIG. 2  is a tool string that may embody or otherwise employ one or more principles of the present disclosure, according to one or more embodiments. 
         FIG. 3  depicts a flowchart illustrating a method embodying one or more principles of the present disclosure, according to one or more embodiments. 
         FIG. 4  depicts a computer system that may embody or otherwise employ one or more principles of the present disclosure, according to one or more embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     The present disclosure relates to downhole measurements and, more particularly, to measuring the tension on a conveyance line with a downhole device. 
     The disclosed embodiments provide systems and methods for monitoring and transmitting the measured tension of a conveyance line used in wellbore operations. A tension sensor and associated data communication equipment are combined into a single unit, thus no longer requiring independent telemetry equipment. Further, embodiments of the presently disclosed devices may be implemented with existing tool strings, which already include casing collar locators and other common downhole tools designed to withstand forces and conditions resulting from particular downhole operations. Due to containing fewer parts and electronics, the systems disclosed herein are more robust and well suited to withstand the violent disturbances that may occur downhole, for example, during perforation operations. 
     Referring to  FIG. 1 , illustrated is a well system  100  that may embody or otherwise employ one or more principles of the present disclosure, according to one or more embodiments. As illustrated, the well system  100  may include a service rig  102  that is positioned on the earth&#39;s surface  104  and extends over and around a wellbore  106  that penetrates a subterranean formation  108 . The service rig  102  may be a drilling rig, a completion rig, a workover rig, or the like. In some embodiments, the service rig  102  may be omitted and replaced with a standard surface wellhead completion or installation. Moreover, while the well system  100  is depicted as a land-based operation, it will be appreciated that the principles of the present disclosure could equally be applied in any sea-based or sub-sea application where the service rig  102  may be a floating platform or sub-surface wellhead installation, as generally known in the art. 
     The wellbore  106  may be drilled into the subterranean formation  108  using any suitable drilling technique and may extend in a substantially vertical direction away from the earth&#39;s surface  104  over a vertical wellbore portion  110 . At some point in the wellbore  106 , the vertical wellbore portion  110  may deviate from vertical relative to the earth&#39;s surface  104  and transition into a substantially horizontal wellbore portion  112 . In some embodiments, the wellbore  106  may be completed by cementing a casing string  116  within the wellbore  106  along all or a portion thereof. As used herein, “casing string” may refer to any downhole tubular or string of tubulars known to those skilled in the art including, but not limited to, wellbore liner, production tubing, drill string, and other downhole piping systems. 
     The system  100  may further include a downhole tool string  120  conveyed into the wellbore  106 . The downhole tool string  120  may be coupled or otherwise attached to a conveyance  118  that extends from the service rig  102 . The conveyance  118  may be, but is not limited to, wireline, slickline, an electric line, coiled tubing, combinations thereof, and the like. In some embodiments, the tool string  120  may be pumped downhole to a target location within the wellbore  106  using hydraulic pressure applied from the service rig  102  at the surface  104 . In other embodiments, the tool string  120  may be conveyed to the target location using gravitational or otherwise natural forces. 
     As will be described in greater detail below, the downhole tool string  120  may include measurement devices, and further include any number of downhole tools. In one embodiment, the sensors included in the downhole tool string  120  may be tension measurement sensors or casing collar locator sensors. In another embodiment, downhole tools included in the tool string  120  may include a wellbore perforating assembly located at or near the distal end of the tool string  120 . In operation, the wellbore perforating assembly may be capable of perforating the casing string  116  and associated cement to allow fluid communication between the wellbore  106  and the formation  108 . 
     The tool string  120  may be communicably coupled to a computer system  122  at the earth&#39;s surface  104  via conveyance  118 . The computer system  122  can be located directly on the rig  102 , or can be located anywhere on the earth&#39;s surface  104  near the rig  102 . Further, the computer system  122  can be located off-site from the rig  102 , wherein information may be sent to, and received by the computer system  122  via any method known to one of skill in the art, including wired or wireless communication methods. As described in more detail below with reference to  FIG. 4 , the computer system  122  may be any general computer system known to one of skill in the art capable of communicating (transmitting and receiving) data or signals with the downhole tool string  120 . In one embodiment, the computer system  122  may allow a well operator to control the downhole tools included in the tool string  120  via hardware or software controls. The computer system  122  may further be capable of receiving signals or data sent from the tool string  120 . The computer system  122  may also include processing capabilities to decode simultaneous signals that may be sent at varying frequencies, discussed in greater detail below. The computer system  122  can then output information received from the tool string  120  to the well operator (or any person at a remote location). 
     While  FIG. 1  depicts the downhole tool string  120  as being arranged and operating in the horizontal portion  112  of the wellbore  106 , the embodiments described herein are equally applicable for use in portions of the wellbore  106  that are vertical, deviated, or otherwise slanted. Moreover, use of directional terms such as above, below, upper, lower, upward, downward, uphole, downhole, and the like are used in relation to the illustrative embodiments as they are depicted in the figures, the upward direction being toward the top of the corresponding figure and the downward direction being toward the bottom of the corresponding figure, the uphole direction being toward the surface of the well and the downhole direction being toward the toe of the well. As used herein, the term “proximal” refers to that portion of the component being referred to that is closest to the wellhead, and the term “distal” refers to the portion of the component that is furthest from the wellhead. 
     Referring now to  FIG. 2 , with continued reference to  FIG. 1 , illustrated is an enlarged view of the exemplary tool string  120 , according to one or more embodiments of the present disclosure. As illustrated, the tool string  120  may be operatively coupled or otherwise attached to the conveyance  118  at a socket coupling  202 . In some embodiments, the tool string  120  may include a load-measuring device  204 , a casing collar locator  206 , one or more perforating guns  208  (two shown), and a lower sub  210 . In at least one embodiment, the tool string  120  may further include a bridge plug setting tool  212 . 
     As discussed above, the conveyance  118  may help convey the tool string  120  to a target location within the wellbore  106  ( FIG. 1 ). The conveyance  118  may also be configured to facilitate communication between the tool string  120  and the computer system  122  ( FIG. 1 ) located at the surface  104 . Such communication may include information and data being sent in both directions A and B (e.g., uphole and downhole, respectively). More specifically, direction A represents information sent from the computer system  122  to the tool string  120  downhole. This may include signals to operate the downhole tools, for example, firing the perforating guns  208  or activating the bridge plug setting tool  212 . In contrast, information sent in direction B may include information sent from the tool string  120  to the computer system  122 . Such information may include measurement data from devices in the tool string  120 , such as data relating to the detection of a casing collar from the casing collar locator  206  or tension information from the load-measuring device  204 . 
     The tool string  120  may be coupled or otherwise attached to the conveyance  118  at the socket coupling  202  using any coupling device known in the art. In one embodiment, for example, the conveyance  118  may be operatively coupled to the tool string  120  using a socket or rope socket. The socket coupling  202  may be designed to separate or sever the conveyance  118  from the tool string  120  upon experiencing a predetermined load. This may prove advantageous in preventing the conveyance  118  from severing at an intermediate location between the surface  104  ( FIG. 1 ) and the tool string  120 , which would then require an expensive fishing operation to retrieve the severed portions of the conveyance  118  and the tool string  120 . As such, the socket coupling  202  may be referred to as a “weak” point in the conveyance  118 . To prevent unwanted disconnection of the conveyance  118  from the tool string  120 , the tension between the conveyance  118  and tool string  120  may be measured in real-time using load-measuring device  204  and reported to the surface  104  for consideration by operators. 
     The load-measuring device  204  may be capable of performing multiple functions, including obtaining various downhole measurements and communicating with the computer system  122  ( FIG. 1 ). In particular, as shown in the adjacent exploded view, the load-measuring device  204  may include one or more sensors  214 , communication equipment  216 , and filter circuitry  218 . Moreover, the load-measuring device  204  may implement a pressure compensation system configured to protect the instruments and equipment arranged therein by means other than a mechanism that equalizes internal and external pressures, as such a mechanism would likely fail under the pressures incurred during perforation operations. 
     The one or more sensors  214  may be configured to measure tensile loads on the conveyance line  118  at or near the socket coupling  202 . To accomplish this, the one or more sensors  214  may encompass any sensor known to one of skill in the art capable of measuring tension. Examples of such include, but are not limited to, load cells or strain gauges (e.g., piezoelectric, piezoresistive, fiber optic, etc.). In one embodiment, a Wheatstone bridge (quarter, half, or full-bridge) configuration may be used. Notably, one of skill in the art will appreciate the robustness of this type of sensor and sensor configuration. Upon acquisition of a signal by the sensor(s)  214 , sensor compensation may be performed on the acquired signal. In one embodiment, compensation may be performed downhole by the sensor(s)  214  or by other hardware or software capabilities of the load-measuring device  204 . In another embodiment, compensation may be performed uphole by hardware or software associated with the computer system  122  ( FIG. 1 ). 
     The communication equipment  216  may be capable of communicating with the computer system  122  at the earth&#39;s surface  104 . The communication equipment  216  may include circuitry to receive or transmit data with the computer system  122  ( FIG. 1 ) via the conveyance  118 . The communication equipment  216  may be capable of transmitting signals directly acquired through the sensor(s)  214 , such as the load cell or strain gauge sensors previously discussed. The communication equipment  216  may also be capable of transmitting signals acquired by other downhole tools or measurement devices within to the tool string  120 , such as the casing collar locator (CCL)  206 . In one embodiment, the communications equipment  216  may implement data transmission of these signals to the computer system  122  by sending each signal individually on one or more transmission lines of the conveyance  118 . In another embodiment, multiple signals may be sent by the communications equipment  216  to the computer system  122  simultaneously, where signals may be sent at varying frequencies. For example, a reading from the CCL  206  may be received by the load-measuring device  204 , and then sent at a first frequency, while the load-measuring device  204  simultaneously sends data from the tension sensor  214  at a second frequency. As mentioned above, the computer system  122  ( FIG. 1 ) will then decompose the signals to obtain individual sensor information. 
     The communication equipment  216  may also receive signals from the computer system  122  in direction A. These signals may be intended to reach downhole tools, thus, the load-measuring device  204  may act similar to a pass-through, receiving such signals from the computer system  122  and allowing them to propagate to their intended downhole tool or device. Examples of such signals may be arming and detonation signals for the perforating guns  208  or a control signal to operate the bridge plug setting tool  212 . 
     The filter circuitry  218  may be configured to assist in preventing signal crosstalk between signals being sent in opposing directions A and B, and thereby preventing unwanted signals from reaching downhole tools. If such crosstalk were to occur and unintended signals ultimately reach the downhole tools, such as the perforating guns  208  and/or the bridge plug setting tool  212 , this may cause unintentional operation of such downhole tools. In such cases, this may result in costly damage to the downhole tools, the tool string  120 , and the wellbore  106  ( FIG. 1 ). For example, if an unintended signal were to reach the perforating guns  208 , this may cause premature detonation of the perforating guns  208  at an unintended depth, which would then require remedial operations to repair the wellbore  106 . One of skill in the art will appreciate that, while implementing filters (e.g., the filter circuitry  219 ) to assist in preventing crosstalk, the filter circuitry  218  must still allow signals intended for downhole tools to propagate therethrough. 
     A person of skill in the art will readily appreciate the distinguishing features of the arrangement within the tool string  120 . For instance, it may be desirable to measure tension on the conveyance  118  at or near the socket coupling  202  downhole, as opposed to measuring tension at the rig  102  or the earth&#39;s surface  104 . This may be especially desirable when operating in a substantially horizontal wellbore portion  112  ( FIG. 1 ), as surface measurements may be inaccurate due to portions of the conveyance  118  resting on the casing  116  when in the horizontal portion  112  of the wellbore  106 . 
     Additionally, traditional telemetry devices are usually arranged below or otherwise incorporated with the CCL  206 . According to the presently described embodiments, the telemetry device and the CCL  206  are arranged separately. For example, the load-measuring device  204  (including the communication equipment  216 ) is located closer to the proximal end of the tool string  120  than the CCL  206 , and is independent of the CCL  206 , thus enabling the load-measuring device  204  to be used with any current tool string. As a result, the load-measuring device  204  may also be used without requiring separate telemetry equipment. 
     Further, as described in the present disclosure, the simplicity and robustness of the load-measuring device  204  allows it to be used in conjunction with perforation operations and other violent downhole operations. In conventional systems, casing collar locators are usually designed similar to typical sensors, thus incapable of withstanding the pressures and forces that may be generated during perforation operations. Similarly, conventional telemetry cartridges and their associated sensors may use pressure compensation systems that equalize internal and external pressures, which likely fail when experiencing dramatic pressure differentials during perforation operations and thus are often omitted from the tool. However, as presently described, the CCL  206  is specially designed to withstand the conditions that occur during perforation operations. Additionally, the load-measuring device  204  implements a pressure compensation system which protects instruments and equipment therein by means other than a mechanism equalizing internal and external pressures. Therefore, the load-measuring device  204  itself may use fewer and more sturdy components, thus being more robust with less chance of communication failure during violent downhole operations. As such, the present disclosure enables use of tension monitoring equipment with tools having a violent nature. 
     The CCL  206  may be used for depth correlation of the tool string  120  and is designed for use in violent downhole operations (e.g., perforating operations). As the CCL  206  passes by a casing joint, or collar, the difference in metal thickness across two magnets associated with the CCL  206  induces a current spike in a coil also associated with the CCL  206 . The CCL  206  is typically a passive device or sensor and may be communicatively coupled to load-measuring device  204 . In exemplary operation, the CCL  206  may be configured to convey its acquired signals to the load-measuring device  204  such that the load-measuring device  204  may transmit such signals to the computer system  122  ( FIG. 1 ). 
     Similar to the CCL  206 , the perforating guns  208  and the bridge plug setting tool  212  may also be communicatively coupled to the load-measuring device  204 . Accordingly, the load-measuring device  204  may receive command signals from the computer system  122  and otherwise act as a pass-through such that the signals are able to reach the perforating guns  208  and the bridge plug setting tool  212 . 
     Referring now to  FIG. 3 , a schematic flowchart of a method  300  of measuring a load on a conveyance line is illustrated, according to one or more embodiments. According to the method  300 , a tool string may be conveyed downhole, as at  302 . As described herein, the tool string may be deployed using any number of conventional deployment methods, such as wireline or slickline deployment. The tool string may include various downhole tools and/or measurement devices, such as a load-measuring device, a casing collar locator, perforating guns used during fracking operations, and/or a bridge plug setting tool. 
     The tool string may be communicably coupled to a computer system at the earth&#39;s surface. More particularly, the load-measuring device of the tool string may include communication equipment capable of communicating with the computer system via the conveyance or via other telemetry methods and systems. The tool string and the computer system may both send and receive signals. In one embodiment, the downhole tool string may be configured to transmit measurements from one or more downhole sensors to the computer system. In another embodiment, command signals originating from the computer system may be conveyed to the tool string downhole and intended to operate the downhole tools as coupled to the tool string. 
     As at  304 , various types of measurements may be acquired using the downhole measurement devices included in the tool string. In one embodiment, such measurement devices may include a casing collar locator that operates to detect casing collars, thus providing the well operator with real-time knowledge of the tool string current depth. In another embodiment, such measurement devices may include the load-measuring device, which may be configured to measure load (e.g., tension), communicate with the computer system at the surface, and/or filter signals (as discussed below). Acquisition of data from the load-measuring device measures strain on the conveyance. Because the coupling between the conveyance and the tool string may have a preset release tension, tension measurement information may be helpful to the well operator to assist preventing unintentional release between the conveyance and the downhole tool string. 
     After measurements have been taken, the data can be transmitted by the load-measuring device to the computer system located at or near the earth&#39;s surface via the conveyance line, as at  306 . In one embodiment, signals may be individually transmitted to the computer system. In another embodiment, the load-measuring device may combine signals to send them simultaneously, but at varying frequencies. The uphole computer system would then decouple the received signals into individual sensor measurements. 
     The downhole tool string can also receive signals from the uphole computer system. Such signals may be intended to operate downhole tools, such as firing a perforating gun or operating a bridge plug setting tool, as at  308 . To prevent crosstalk, the load-measuring device may implement filter circuitry. The filter circuitry may assist preventing crosstalk by allowing signals intended for downhole tools to pass through, but simultaneously preventing uphole signals from accidentally being communicated back downhole. 
     Referring now to  FIG. 4 , with reference again to  FIG. 1 , illustrated is an exploded view of the computer system  122 , according to one or more embodiments. As illustrated, the computer system  122  may include components such as a bus  402 , a controller  404 , memory  406 , a communications unit  408 , and peripheral devices  410 . Computer programs or algorithms executed by computer system  122  may be implemented using software, hardware, or a combination of both. In some embodiments, the computer system  122  may be arranged at or near the service rig  102 . In other embodiments, however, the computer system  122  may be remotely located. 
     The bus  402  may provide electrical conductivity and a communication pathway among the various components of the computer system  122 . The controller  404  may be a general-purpose microprocessor, a microcontroller, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA), a Programmable Logic Device (PLD), a controller, a state machine, gated logic, discrete hardware components, or any other suitable device that can perform calculations or other manipulations of information. 
     The memory  406  can be one or more machine-readable media. Machine-readable media may include storage integrated into a processing system, such as might be the case with an ASIC. Machine-readable media may also include storage external to a processing system, such as a Random Access Memory (RAM), a flash memory, a Read Only Memory (ROM), a Programmable Read-Only Memory (PROM), an Erasable PROM (EPROM), registers, a hard disk, a removable disk, a CD-ROM, a DVD, or any other suitable storage device. In one aspect, a machine-readable medium is a non-transitory machine-readable medium, a machine-readable storage medium, or a non-transitory machine-readable storage medium. In one aspect, a computer-readable medium is a non-transitory computer-readable medium, a computer-readable storage medium, or a non-transitory computer-readable storage medium. Instructions may be executable, for example, by a client device or server or by a processing system of a client device or server. Instructions can be, for example, a computer program including code. 
     The communications unit  408  may be capable of communication, both sending and receiving signals, with the tool string  120  ( FIG. 1 ) located downhole via the conveyance  118 . Example signals that may be sent from communications unit  408  to the tool string  120  may include signals to operate downhole tools, such as firing a perforating gun or setting a bridge plug. Example signals that may be received by the communications unit  408  from the downhole tool string  120  may include sensor signals such as from a casing collar locator or a tension sensor. Further, should the computer system  122  be remote from the rig  102 , the communications unit  408  may handle communications with any device acting as an intermediary (not shown) in between the computer system  122  and the tool string  120 . 
     Additionally, the computer system  122  may include one or more peripheral devices  410 . The peripheral devices  410  may include, but are not limited to, a monitor (e.g., displays, GUIs, etc.), user input devices (e.g., keyboard, mouse, touchscreen, hardware or software controls, etc.), a printer, additional storage memory, etc. In one embodiment, peripheral devices  410  may be a touchscreen panel configured to both inform a well operator as to downhole conditions and signals, and allow the well operator to send signals to downhole tools. 
     Therefore, the disclosed systems and methods are well adapted to attain the ends and advantages mentioned as well as those that are inherent therein. The particular embodiments disclosed above are illustrative only, as the teachings of the present disclosure may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. Furthermore, no limitations are intended to the details of construction or design herein shown, other than as described in the claims below. It is therefore evident that the particular illustrative embodiments disclosed above may be altered, combined, or modified and all such variations are considered within the scope of the present disclosure. The systems and methods illustratively disclosed herein may suitably be practiced in the absence of any element that is not specifically disclosed herein and/or any optional element disclosed herein. While compositions and methods are described in terms of “comprising,” “containing,” or “including” various components or steps, the compositions and methods can also “consist essentially of” or “consist of” the various components and steps. All numbers and ranges disclosed above may vary by some amount. Whenever a numerical range with a lower limit and an upper limit is disclosed, any number and any included range falling within the range is specifically disclosed. In particular, every range of values (of the form, “from about a to about b,” or, equivalently, “from approximately a to b,” or, equivalently, “from approximately a-b”) disclosed herein is to be understood to set forth every number and range encompassed within the broader range of values. Also, the terms in the claims have their plain, ordinary meaning unless otherwise explicitly and clearly defined by the patentee. Moreover, the indefinite articles “a” or “an,” as used in the claims, are defined herein to mean one or more than one of the element that it introduces. If there is any conflict in the usages of a word or term in this specification and one or more patent or other documents that may be incorporated herein by reference, the definitions that are consistent with this specification should be adopted. 
     As used herein, the phrase “at least one of” preceding a series of items, with the terms “and” or “or” to separate any of the items, modifies the list as a whole, rather than each member of the list (i.e., each item). The phrase “at least one of” does not require selection of at least one item; rather, the phrase allows a meaning that includes at least one of any one of the items, and/or at least one of any combination of the items, and/or at least one of each of the items. By way of example, the phrases “at least one of A, B, and C” or “at least one of A, B, or C” each refer to only A, only B, or only C; any combination of A, B, and C; and/or at least one of each of A, B, and C.