Patent Application
20240352853
In drilling a borehole into an earthen formation, such as for the recovery of hydrocarbons or minerals from a subsurface formation, a drill string is formed from a plurality of pipe joints connected end-to-end with a drill bit at the lower end. The drill bit is rotated, by rotation of the drill string or operation of a motor, so that the drill bit progresses downward into the earth to create a borehole along a predetermined trajectory. The drill string may include sensors that gather information about downhole operations. Information collected by the sensors may be transmitted to a device at the surface using any of a variety of communication methods. Mud pulse telemetry systems provide communication between the sensors incorporated in the drill string and the surface by modulating the pressure of drilling fluid flowing from the surface to the drill bit through the drill string.
In one example, a drilling system includes a drill string and surface equipment. The drill string includes a mud pulse transmitter. The mud pulse transmitter is configured to provide a first mud pulse transmission at a first rate responsive to drilling, and provide a second mud pulse transmission at a second rate responsive to not drilling. The surface equipment is coupled to the drill string. The surface equipment includes a mud pulse receiver. The mud pulse receiver is configured to receive the first mud pulse transmission at the first rate responsive to drilling, and receive the second mud pulse transmission at the second rate responsive to not drilling. The second rate is higher than the first rate.
In another example, a method for downhole communication includes providing, by a downhole mud pulse transmitter, a first mud pulse transmission at a first rate responsive to drilling, and receiving, by a surface mud pulse receiver, the first mud pulse transmission at the first rate responsive to drilling. The method also includes providing, by the downhole mud pulse transmitter, a second mud pulse transmission at a second rate responsive to not drilling, and receiving, by the surface mud pulse receiver, the second mud pulse transmission at the second rate responsive to not drilling.
In a further example, a downhole tool includes a mud pulse transmitter. The mud pulse transmitter includes a pulser and an encoder. The pulser is configured to modulate a pressure of drilling fluid flowing through the downhole tool. The encoder is coupled to the pulser. The encoder is configured to control the pulser to: provide a first mud pulse transmission at a first rate responsive to a resumption of drilling fluid circulation through the downhole tool, and provide a second mud pulse transmission at a second rate responsive to completion of the first mud pulse transmission.
For a detailed description of various examples, reference will now be made to the accompanying drawings in which:
Sensors 128 provided in the tool string 126 acquire information concerning various aspects of drilling operation (e.g., information about the formation being drilled). For example, resistivity sensors may be used to transmit, and then receive, high frequency wavelength signals (e.g., electromagnetic waves) that travel through the formation surrounding the sensors 128. By comparing the transmitted and received signals, information can be determined concerning the nature of the formation through which the signal traveled, such as whether it contains water or hydrocarbons. Other sensors are used in conjunction with magnetic resonance imaging (MRI). Still other sensors include gamma scintillators, which are used to determine the natural radioactivity of the formation, and nuclear detectors, which are used to determine the porosity and density of the formation.
The sensors 128 may also provide information concerning the direction of the drilling. This information can be used, for example, to control the direction in which the drill bit 114 advances while drilling. Such sensors may include a magnetometer to sense azimuth, and accelerometers to sense inclination and tool face direction.
The information collected by the sensors 128 may be transmitted to the surface equipment for analysis. Such data transmission may be provided using mud pulse telemetry. In a mud pulse telemetry system, signals from the sensors 128 are received and processed in a mud pulse transmitter 130 included in the tool string 126. The mud pulse transmitter 130 may include a data encoder and a pulser. The data encoder digitally encodes the sensor data. The pulser may include a valve that is opened and closed to generate pressure pulses in the flow of drilling fluid. The pressure pulses represent the encoded information. The pressure pulses are defined by a variety of characteristics, including amplitude (the difference between the maximum and minimum values of the pressure), duration (the time interval during which the pressure is increased), shape, and frequency (the number of pulses per unit time). Variation of the pressure pulse characteristics may represent either a single data bit (i.e., binary modulation) or multiple data bits (i.e., non-binary modulation) of digital data. The mud pulse transmitter 130 may implement any of a variety of pulse encoding algorithms.
The pressure pulses generated by the mud pulse transmitter 130 travel up the column of drilling fluid flowing down to the drill bit 114, and are sensed by a mud pulse receiver 138 provided in the surface equipment. The mud pulse receiver 138 includes a pressure transducer that detects the changes in fluid pressure caused by the mud pulse transmitter 130. The pressure transducer provides an output signal representing the detected pressure changes. The mud pulse receiver 138 is communicatively coupled to a drilling control system 132. Telemetry decoding circuitry included in the mud pulse receiver 138 of the drilling control system 132 can decode and analyze the received signal (provided by the pressure transduce) to extract the information transmitted by the mud pulse transmitter 130. The drilling control system 132 may apply the information to control drilling operations. For example, the drilling control system 132 may apply azimuth, inclination, and tool face direction information to control directional drilling.
As the borehole 116 is extended into the formation, drilling operations must be periodically suspended to add drill pipe 118 to the drill string 108. A drill pipe 118 may be about 10 meters (m) in length, and the drill pipe 118 may be added to the drill string 108 in three pipe sections referred to as stands. Accordingly, in some examples, each time the borehole 116 has been extended by about 30 m, drilling operations are halted to add a new stand of drill pipe to the drill string 108. While drilling is halted to extend the drill string 108 drilling fluid is not being pumped through the drill string 108, and the mud pulse transmitter 130 is unable to communicate with the surface equipment. When the new drill pipe has been added to the drill string 108, pumping of drilling fluid resumes and the mud pulse transmitter 130 is able to modulate the fluid pressure and communicate with the surface equipment. The sensors 128 can detect whether drilling fluid is circulating (e.g., by sensing vibration or flow). In some examples of the drilling system 100, after the new drill pipe has been added to the drill string 108 and drilling fluid circulation has resumed, sensors 128 detect the circulation of drilling fluid, and the mud pulse transmitter 130 transmits survey data (a survey frame) to the surface equipment. The survey data may include inclination, azimuth, gravity, magnetic field and/or other measurements. The drilling control system 132 may delay the commencement of drilling (e.g., delay rotation of the drill string 108 and/or the drill bit 114) until the survey data has been received (e.g., to apply the survey data to control drilling direction).
In the survey time interval between when the circulation of drilling fluid resumes, and drilling resumes, the communication channel provided by the drilling fluid is less noisy than when drilling (e.g., when the drill bit 114 is rotating). Because the communication channel is less noisy, the mud pulse transmitter 130 may provide the survey data at a higher transmission rate than is used while drilling. For example, while drilling, the mud pulse transmitter 130 may transmit at a first rate, and during the survey time interval the mud pulse transmitter may transmit at a second rate that is higher than the first rate. In some implementations the second rate may be 1.5 times, 2 times, etc. higher than the first rate. By increasing the transmission rate during the survey time interval, the survey data transmission time is reduced, and drilling can resume sooner than would be otherwise possible. Accordingly, the idle time (time spent not drilling) of the drilling system 100 is reduced and the expense of drilling the borehole 116 is reduced.
After the mud pulse transmitter 130 transmits the survey data, the mud pulse transmitter 130 may lower the transmission rate to provide reliable communication of drilling data while drilling. The drilling data may include tool face angle, drill bit rotation speed (revolutions per minute), gamma ray measurements, vibration measurements, temperature measurements, and/or other measurements. The mud pulse receiver 138 and the drilling control system 132 may be configured to receive mud pulse telemetry at the second (higher) rate in the survey time interval (e.g., after resumption of drilling fluid circulation following addition of a stand of pipe) and receive mud pulse telemetry at the first (lower) rate while drilling (e.g., after transmission/reception of the survey data). In some implementations of the drilling system 100, the first and second rates are programmed into the mud pulse transmitter 130 and the mud pulse receiver 138 prior to deployment.
The encoder 202 is coupled to the pulser 204. The encoder 202 generates a control signal 210 that is provided to the pulser 204. The control signal 210 controls the operation of the pulser 204 to encode data in drilling fluid pressure variations. The encoder 202 is also coupled to the sensors 128 for reception of various measurements provided by the sensors 128. In practice, the encoder 202 may be coupled to the sensors 128 through processing and conditioning circuits that prepare the measurements received from the sensors 128 for transmission via the mud pulse transmitter 130. The sensor measurements and any other information encoded in the control signal 210 by the encoder 202 may be stored in a memory provided within the encoder 202 or external to the encoder 202 in various examples of the mud pulse transmitter 130.
The encoder 202 may receive as inputs a survey rate 206 and a drill rate 208 that specify transmission rates for transmission of data from the tool string 126 to the surface equipment. The survey rate 206 may specify a higher transmission rate than the drill rate 208. In various implementations of the mud pulse transmitter 130, the survey rate 206 and the drill rate 208 may be stored in memory. The memory in which the survey rate 206 and the drill rate 208 are stored may be provided within the encoder 202 or external to the encoder 202. The encoder 202 may select which of the survey rate 206 and the drill rate 208 is to be used to transmit data to the surface equipment based on the measurements provided by the sensors 128. For example, if the measurements provided to the sensors 128 indicate that the drill string 108 and/or the drill bit 114 are rotating to drill the borehole 116, then because noise in the drilling fluid increases, with drilling, the encoder 202 may select the drill rate 208 to improve communication reliability. If the measurements provided by the sensors 128 indicate that the drill string 108 and/or the drill bit 114 are not rotating to drill the borehole 116, then the encoder 202 may select the survey rate 206 to decrease transmission time.
When drilling is halted to add a stand of drill pipe to the drill string 108, the measurements provided by sensors 128 may indicate that drilling is halted by detecting that the circulation of drilling fluid through the drill string 108 has been a halted (e.g., operation of the pump 120 has been suspended), rotation of the drill string 108 or the drill bit 114 is halted, etc. When the stand of drill pipe has been connected to the drill string 108, and the circulation of drilling fluid in the drill string 108 resumes, the sensors 128 may detect the resumption of drilling fluid circulation. Based on an indication of the resumption of drilling fluid circulation provided by the sensors 128, the encoder 202 may select the survey rate 206 for use in transmission of survey data (e.g., a survey frame) to the surface equipment. When transmission of the survey data is complete, the surface equipment may resume drilling, and the encoder 202 may select the drill rate 208 for use in transmission of drilling data to the surface equipment. Accordingly, the mud pulse transmitter 130 reduces the transmission time of survey data and reduces the time that drilling is halted when a new stand of pipe is added to the drill string 108.
The decoder 302 may receive as inputs the survey rate 206, the drill rate 208, and a control signal 312. In various implementations of the mud pulse receiver 138, the survey rate 206 and the drill rate 208 may be stored in memory. The memory in which the survey rate 206 and the drill rate 208 are stored may be provided within the decoder 302 or external to the decoder 302. The decoder 302 may select which of the survey rate 206 and the drill rate 208 is to be used to receive (e.g., decode) data transmitted by the tool string 126 based on the control signal 312. For example, the control signal 312 may indicate which of the survey rate 206 or the drill rate 208 is to be applied to receive mud pulse transmission. The control signal 312 may be provided, for example, by the drilling control system 132 based on the current state of the drilling system 100. If the drilling control system 132 is rotating the drill string 108 and/or the drill bit 114 to drill the borehole 116, then the control signal 312 may be set to cause the decoder 302 to select and apply the drill rate 208 (to improve communication reliability). If the drilling control system 132 is not rotating the drill string 108 and/or the drill bit 114 (not drilling the borehole 116), then the control signal 312 may be set to cause the decoder 302 to select and apply the survey rate 206 (to decrease communication time).
When the drilling control system 132 halts drilling to add a stand of drill pipe to the drill string 108, the drilling control system 132 halts the circulation of drilling fluid through the drill string 108 (e.g., halts operation of the pump 120). When the stand of drill pipe has been connected to the drill string 108, the drilling control system 132 reactivates the pump 120 to resume the circulation of drilling fluid in the drill string 108. While drilling is halted, before or at the resumption of drilling fluid circulation, the drilling control system 132 may set the control signal 312 to cause the decoder 302 to use the survey rate 206 for reception of survey data via mud pulse telemetry. When reception of the survey data (reception of the survey frame) is complete, the drilling control system 132 may resume drilling, and the drilling control system 132 may set the control signal 312 to cause the decoder 302 to use the drill rate 208 for reception of drill data via mud pulse telemetry. Accordingly, the mud pulse receiver 138 operates in conjunction with the mud pulse transmitter 130 to reduce the time that drilling is halted when a new stand of pipe is added to the drill string 108.
In block 402, the drill string 108 and/or the drill bit 114 are rotating to drill and extend the borehole 116. The sensors 128 acquire drilling data (e.g., tool face angle, drill bit rotation speed (revolutions per minute), gamma ray measurements, vibration measurements, temperature measurements, etc.). The mud pulse transmitter 130 transmits a drill frame containing the drilling data to the surface equipment at the drill rate.
In block 404, the tool string 126 determines whether drilling is ongoing. If drilling is ongoing, then acquisition and transmission of drilling data continues in block 402. Suspension of drilling may be determined by sensing motion of the drill string 108, such as lack of rotation, lifting of the drill string 108, lack of drilling fluid circulation, etc. If drilling is halted in block 404, then circulation of drilling fluid is halted in conjunction with suspension of drilling, and the sensors 128 acquire survey data (e.g., inclination, azimuth, gravity, magnetic field, tool face direction, etc.) in block 406.
In block 408, the tool string 126 determines whether the circulation of drilling fluid has resumed. For example, the sensors 128 may include a flow sensor or a vibration sensor that detects drilling fluid circulation. If the circulation of drilling fluid in the drill string 108 has resumed, then the mud pulse transmitter 130 transmits the survey data (e.g., a survey frame) at the survey rate. The mud pulse transmitter 130 may transmit a synchronization pattern at the survey rate prior to transmission of the survey frame. The synchronization pattern may include any symbol sequence suitable for indicating initiation of frame transmission. A explained herein, the survey rate is higher than the drill rate.
Following transmission of the survey data, the mud pulse transmitter 130 is set to transmit at the drill rate, and acquisition and transmission of drill data, at the drill rate, continues in block 402.
In block 502, the drill string 108 and/or the drill bit 114 are rotating to drill and extend the borehole 116. The mud pulse receiver 138 is set to receive mud pulse telemetry at the drill rate. The mud pulse receiver 138 receives drilling data (e.g., a drill frame) transmitted by the mud pulse transmitter 130 at the drill rate.
In block 504, the drilling control system 132 determines whether the drilling has reached a point at which the drill string 108 should be extended to enable further drilling. For example, if a length of the drill string 108 above the drill floor is less than a predetermined length, then the drill string 108 should be extended.
If the drill string 108 is to be extended, then, in block 506, the drilling control system 132 halts drilling, halts circulation of drilling fluid, and a new stand of drilling pipe is connected to the drill string 108.
In block 508, the drilling control system 132 determines whether connection of the new stand of drilling pipe to the drill string 108 is complete. If connection of the new stand of drilling pipe is complete, then the drilling control system 132 resumes circulation of drilling fluid in block 510. For example, the drilling control system 132 activates the pump 120 to circulate drilling fluid in the drill string 108.
In block 512, after resuming circulation of drilling fluid, the mud pulse receiver 138 is set to receive mud pulse telemetry at the survey rate. The mud pulse receiver 138 receives survey data (a survey frame) transmitted by the mud pulse transmitter 130 at the survey rate.
In block 514, the drilling control system 132 or the mud pulse receiver 138 determines whether all of the expected survey data (the entire survey frame) has been received. For example, the drilling control system 132 or the mud pulse receiver 138 may determine whether a predetermined number of symbols defining the survey frame have been received at the survey rate.
If all of the expected survey data has been received by the mud pulse receiver 138, then the drilling control system 132 resumes drilling in block 516. With the resumption of drilling, the mud pulse receiver 138 is set (e.g., by the drilling control system 132) to receive mud pulse telemetry at the drill rate in block 402.
The graph 604 shows timing of mud pulse telemetry using variable rate mud pulse telemetry as described herein. In the graph 604, connection of a new stand of drill pipe and resumption of drilling fluid circulation takes about 180 seconds (the same as in the graph 602), acquisition of survey data and transmission of a synchronization pattern takes about 55 seconds, and transmission of the survey data takes about 100 seconds. The reduction in the transmission times of the synchronization pattern and the survey frame are achieved by transmitting at the survey rate described herein. Accordingly, in graph 604, about 335 seconds are spent not drilling in connection with addition of a new stand of drill pipe. Thus, in this example, using variable rate mud pulse telemetry, the drilling system 100 reduces the time spent not drilling by about 55 seconds each time the drill string 108 is extended.
Certain terms have been used throughout this description and claims to refer to particular system components. As one skilled in the art will appreciate, different parties may refer to a component by different names. This document does not intend to distinguish between components that differ in name but not function. In this disclosure and claims, the terms “including” and “comprising” are used in an open-ended fashion, and thus should be interpreted to mean “including, but not limited to . . . ” Also, the term “couple” or “couples” is intended to mean either an indirect or direct connection. Thus, if a first device couples to a second device, that connection may be through a direct connection or through an indirect connection via other devices and connections. The recitation “based on” is intended to mean “based at least in part on.” Therefore, if X is based on Y, X may be a function of Y and any number of other factors.
A device that is “configured to” perform a task or function may be configured (e.g., programmed and/or hardwired) at a time of manufacturing by a manufacturer to perform the function and/or may be configurable (or reconfigurable) by a user after manufacturing to perform the function and/or other additional or alternative functions. The configuring may be through firmware and/or software programming of the device, through a construction and/or layout of hardware components and interconnections of the device, or a combination thereof.
A circuit or device that is described herein as including certain components may instead be adapted to be coupled to those components to form the described circuitry or device. For example, a structure described as including one or more elements may instead include only some of the elements within a single physical device and may be adapted to be coupled to at least some of the elements to form the described structure either at a time of manufacture or after a time of manufacture, for example, by an end-user and/or a third-party.
In this description, unless otherwise stated, “about,” “approximately” or “substantially” preceding a parameter means being within +/−10 percent of that parameter or, if the parameter is zero, a reasonable range of values around zero.
The above discussion is meant to be illustrative of the principles and various embodiments of the present invention. Numerous variations and modifications will become apparent to those skilled in the art once the above disclosure is fully appreciated. It is intended that the following claims be interpreted to embrace all such variations and modifications.
