CONSTANT CIRCULATION SYSTEM

BACKGROUND

[0001] This application claims the benefit of U.S. Provisional Application No. 62/356709 filed on June 30, 2016 incorporated by reference herein in its entirety.

[0002] Measurement-while-drilling (MWD) and logging- while-drilling (LWD) systems provide information about conditions at the bottom of a wellbore substantially in real time as the wellbore is being drilled. This information includes directional drilling variables such as inclination and direction (azimuth) of the drill bit, and geological formation data, such as natural gamma ray radiation levels and electrical resistivity of the rock formation. Typically, MWD tools or instruments make the directional and other drilling-related measurements, and LWD tools or instruments make the geological formation measurements. Often MWD and LWD tools are integrated into a single instrument package and are called M WD 'LWD tools. As used herein, the term "MWD system" refers to MWD, LWD, and combination MWD/LWD tools or instruments. The term MWD system includes equipment and techniques for data transmission from within the well to the earth's surface. MWD systems measure well bore characteristics and transmit signals regarding the characteristics to the earth's surface. "Mud pulse" telemetry and electromagnetic telemetry may be used to transmit the signals.

[0003] MWD systems measure parameters within the wellbore, and can transmit the acquired data to the earth's surface from within the wellbore. There are several different methods for transmitting data to the surface, including "mud pulse" telemetry and electromagnetic telemetry.

[0004] In mud-pulse telemetry, data is transmitted from the MWD system in the wellbore to the surface by generating pressure waves in the drilling mud.

[0005] However, standard MWD systems do not allow for MWD signals to be received at the surface when a new stand of drill pipe is being added to a drill string as the drill string is being tripped into the wellbore. This is even true for MWD systems implemented in continuous circulation systems that provide constant circulation of drilling mud while new stands of drill pipe are added to a drill string as the drill string trips into the wellbore.

[0006] There is a need for a MWD systems that allows the drill sting to be rotated at all times during the circulation of drilling mud.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007] A more complete understanding of the present embodiments may be acquired by referring to the following description taken in conjunction with the accompanying drawings, in which like reference numbers indicate like features.

[0008] FIGURE 1 illustrates a prior art measurement while drilling system

[0009] FIGURE 2 illustrates a measurement while drilling system of the present application for constantly receiving MWD signals while tripping drill string with constant circulation of drilling mud.

[0010] FIGURE 3 shows a cross-sectional side view of a constant circulation sub.

[0011] FIGURE 4 illustrates a measurement while drilling system of the present application for constantly receiving MWD signals while tripping drill string with constant circulation of drilling mud.

[0012] FIGURE 5 shows a transducer of an MWD system positioned in a chamber of a circulation coupler.

DETAILED DESCRIPTION

[0013] Embodiments may be understood by reference to FIGURES 2-5 below in view of the following general discussion. The present disclosure may be more easily understood in the context of a high level description of certain embodiments.

[0014] FIGURE 1 illustrates a drilling system that is equipped for an MWD system that uses mud- pulse telemetry. As shown, the drilling system includes a drill string 13 hanging from a derrick 10. The drill string 13 extends through a rotar' table 18 on the rig floor 16 into the wellbore 21. A drill bit 15 is attached to the end of the drill string 13 , During downhole drilling operations, an earth-boring drill bit 15 is rotated with some of the weight of the drill string applied to the bit. The drill bit 15 may be rotated by rotating the entire drill sting 13 from the surface using the rotary table 18, or alternatively by using a top drive (not shown). While rotating, the drill bit engages the earthen formation and proceeds to form a borehole along a predetermined path toward a target zone. Because of the energy and friction involved in drilling a wellbore in the earth' s formation, drilling fluids, commonly referred to as drilling mud, are used to lubricate and cool the drill bit 15 as it cuts the rock formations below. Furthermore, in addition to cooling and lubricating the drill bit 15, drilling mud also performs the secondary and tertiary functions of removing the drill cuttings from the bottom of the wellbore and applying a hydrostatic column of pressure to the drilled wellbore 21.

[0015] Typically, drilling mud is delivered to the drill bit 15 from the surface under high pressure through a central bore of the drill string. From the central bore of the drill string 13, nozzles on the drill bit 15 direct the pressurized mud to the cutters on the drill bit 15 where the pressurized mud cleans and cools the bit. As the fluid is delivered downhole through the central bore of the drill string 13, the fluid returns to the surface in an annulus 22 formed between the outside of the drill string and the inner profile or wall of the drilled wellbore 21. Drilling mud returning to the surface through the annulus 22 does so at lower pressures and velocities than at its delivery to the drilled wellbore. Nonetheless, a hydrostatic column of drilling mud typically extends from the bottom of the hole up to a bell nipple of a diverter assembly 24 on the drilling rig. Annular fluids exit the bell nipple where solids are removed, the mud is processed, and then prepared to be re-delivered to the subterranean wellbore through the drill string

[0016] One or more sensors or transducers 61 are located in a measurement module 62 in a bottomhole assembly portion of the drill string 13 to measure selected downhole conditions. The measurements made by the transducers 61 may be transmitted to the surface through the drilling mud in the drill string 13. The transducers 61 send signals that are representative of the measured downhole condition to a downhole electronics unit 63. The downhole electronics unit 63 arranges the collected measurements into a selected telemetry format, usually a digital representation of the measurements made by the transducers 61. The telem etry format is then passed to a modulator 64, which groups bits into symbols and then uses a process called modulation to impress the symbols onto a baseband or carrier waveform that can be transmitted through the drilling mud. A symbol consists of a group of one or more bits. The modulated signals serve as input to an acoustic transmitter 65 and valve mechanism 66 that generates a telemetry pressure wave that ultimately carries data to the surface. One or more pressure transducers 67 located on the standpipe 32 generate signals that are representative of variations in the pressure of the mud. The outputs of the pressure transducers 67 can be digitized in analog-to-digital converters and processed by a signal processing module 68, which recovers the symbols from the pressure variations and then sends data recovered from the symbols to a computer 69 where the transmitted information can be accessed by the drilling operators.

[0017] There are several mud-pu! se telemetry systems known in the art. These include positive- pulse, negative-pulse, and continuous-wave. In a positive-puise system, valve mechanism 66 of the transmitter 65 creates a pressure pulse at higher pressure than that of the drilling mud by momentarily restricting flow in the drill string 13. In a negative mud -pulse telemetry system, the valve mechanism 66 creates a pressure pulse at lower pressure than that of the mud by venting a small amount of the mud in the drill siring 13 through the valve 66 to the well annul us 22. In both the positive-pulse and negative-pulse systems, the pressure pulses propagate to the surface through the drilling mud in the drill string 13 and are detected by the pressure transducers 67. To send a stream of data, a series of pressure pulses are generated in a pattern that is recognizable by the signal processing module 68.

[0018] The pressure pulses generated by positive-puise and negative-pulse systems are discrete pressure waves. Continuous wave telemetry can be generated with a rotary valve or "mud siren." In a continuous-wave system, the valve mechanism 66 rotates so as to repeatedly interrupt the flow of the drilling mud in the drill string 13. This causes a periodic pressure wave to be generated at a rate that is proportional to the rate of interruption. Information is then transmitted by modulating the phase, frequency, or amplitude of the periodic wave in a manner related to the downhole measured data.

[0019] FIGURE 2 shows an embodiment of the present disclosure. Like elements have like numerals. A drilling derrick 10 supports a crown block 11 and a travelling block 12 for making up drill pipe 14 sections of a drill string 13. A top drive 20 is suspended from the travelling block 12. A drill bit 15 is made up to the end of the drill string 13. The drill string 13 is suspended from the rig floor 16 via slips 17 in a rotary table 18 so that a stump 19 extends above the rig floor 16. The drill string 13 extends into the wellbore 21 so that there is an annulus 22 between the exterior of the drill sting 13 and the walls of the wellbore 21. A surface casing 23 extends from the top of the wellbore 21 and a rotating control device 24 is attached to the top of the surface casing 23. A blow out preventer (BOP), not shown, may be incorporated into the surface casing.

[0020] The telemetry system of the drilling system includes a measurement module 62 (including therein one or more transducers or sensors 61), an electronics unit 63, a modulator 64, an acoustic transmitter 65, sensors 67, a signal processing module 68, and a computer 69. The measurement module 62, electronics unit 63, modulator 64, and transmitter 65 correspond to a downhole portion of the telemetry system, and the sensors 67, receiver 68 and computer 69 correspond to a surface portion of the telemetry system. The downhole portion of the telemetry system is operatively connected to the surface portion of the telemetry system via the flow of drilling mud. The measurement module 62 generates messages that can be transmitted to the computer 69. These messages include information that is of interest to the drilling operators, e.g., directional and drilling data, drill bit conditions, and geological formation data. The measurement module 62 includes one or more transducers (or sensors) 61 which measure selected parameters, such as drilling and/or earth formation petrophysical parameters, conditions at the drill bit and generate electrical signals related to the parameters measured

[0021] Drilling mud is circulated via a mud pump 30. In some embodiments, the drilling mud is continuously circulated downhole, including during the addition of drill pipe 14 to the drill string 13. The drilling mud is supplied to the drill string 13 via a diverter manifold 31. A pressure line 36 extends from the mud pump 30 to the diverter manifold 31. A line extends from the diverter manifold 31 to the stand pipe 32, wherein the stand pipe 32 is connected to the top drive 20 via a rotary hose 33. Another line extends from the diverter manifold 31 to a floor pipe 34, wherein the floor pipe 34 is connected to a circulation coupler 40 via a rotary hose 35. The circulation coupler 40 is supported above the rig floor 16 via an arm 41. As shown in FIGURE 5, the circulation coupler 40 may include a clamp that grips a constant circulation sub 50, thus connecting the circulation coupler 40 and the constant circulation sub 50. [0022] A discharge line 37 extends from the diverter manifold 31 to a retention tank or sump 38. Drilling mud being circulated up the annulus 22 is returned to the retention tank 38 via return line 39 connected to the surface casing 23 below the rotating control device 24. Drilling mud from the retention tank 38 is supplied to the mud pump 30 via a supply line 42. The diverter manifold 31 is configured to supply drilling mud to the drill string 13 either by the top drive 20 or the circulation coupler 40.

[0023] One or more sensors or transducers 61 are located in the measurement module 62 in a bottomhole assembly portion of the drill string 13 to measure selected downhole conditions. For example, the transducer 61 may be a strain gage that measures weight-on-bit (axial force applied to the bit 15) or a thermocouple that measures temperature at the bottom of the well 21. Additional sensors may be provided as necessary to measure other drilling and formation parameters such as those previously described.

[0024] The measurements made by the transducer 61 in the measurement module 62 may be digitized by passing them through analog-to-digital converters (not shown). A group of binary digits, or bits, thus generated, representing the measurements (hereafter referred to as measurement words) are transferred to the electronics unit 63. In the electronics unit 63, extra bits may be added to the measurement words. The extra bits can be used for error detection and correction or for identification of the measurement words. The measurement words may also be filtered or compressed to improve bandwidth efficiency. The electronics module 63 may group the measurement words into data frames. Extra bits for frame synchronization, channel identification, equalizer training, or error detection and correction may be included in the data frames. The format of the telemetry actually used in any embodiment disclosed herein is a matter of choice for the system designer and is not intended to limit the invention.

[0025] The output of the electronics unit 63 is a bit stream that is the input to the modulator 64.

The modulator 64 groups the bits from the output of the electronics unit 63 into symbols and then impresses these symbols onto a waveform that is suitable for propagation over the mud channel. The size of a symbol may be one or more bits. The output of the modulator 64 is transferred to the transmitter 65, which produces the pressure pulses or waves that propagate through the mud channel. The telemetry waveform may be a baseband waveform. In this example, symbols are transmitted using a technique called line coding. Examples of line codes that can be used to impress the information on to the baseband waveform include non-return- to-zero (NRZ), Manchester code, Miller code, time analog, and pulse position modulation. Line codes for mud pulse telemetry are known in the art.

[0026] The transmitter 65 uses the telemetry waveform signal generated by the modulator 64 to control the valve mechanism 66, which alters the flow of mud in the drill string 13 to generate a pressure wave. In one embodiment, the mechanism 66 is a rotary valve or "mud siren" that generates periodic waveforms in fluid. The valve mechanism 66 does not have to be a mud siren, but may alternatively be a type that generates positive pressure pulses or negative pressure pulses. Such valves can be of any of any type well known in the art.

[0027] The signal wave generated by the transmitter 65 and valve mechanism 66 propagates to the receiver 68 through the mud channel. The mud pumps 30 provide the flow of mud that passes from the mud tanks 38, through the surface piping, standpipe 32, rotary hose 33, drill sting 13, out through nozzles in the drill bit 15 to return to the surface via the annulus 22. At the surface the mud is returned to the mud tanks 38, where rock cuttings are also removed from the mud.

[0028] During drilling, the mud pump 30 injects drilling mud through the top drive 20 into the drill string 13, suspended within the circulation coupler 40. The diverter manifold 31 is operated to selectively direct drilling mud to either the top drive or the circulation coupler 40. Thus, two flow paths are formed which are used to convey fluid into the drill string 13. The mud pump 30 injects drilling mud through the top drive 20 connected to the stump 19 of the drill string 13. In this case, valve VI may be open and valves V2 and V3 may be closed. When a stand of drill pipe 14 needs to be added to the drill string 13, with continuous circulation, the drill string 13 is raised and the slips 17 set.

[0029] The drill string may continue to be rotated via the rotary table 18 or the top drive 20. The circulation coupler 40 is positioned on the drill string 13 so that it engages the constant circulation sub 50, having a radial port, made up to the topmost stand of drill pipe 14 in the drill string 13. The operator may then increase a supply of drilling mud to the circulation coupler 40 while a supply of drilling mud to the top drive 20 is decreased, so as to maintain a constant circulation while the supply is shifted from the top drive 20 to the circulation coupler 40.

[0030] Referring to FIGURE 3, the constant circulation sub 50 includes a short pipe-shaped body 54 being configured to be coupled at both ends to drill pipes. In some embodiments, the constant circulation sub 50 includes an axial valve 51 on one end, a radial valve 52 on an opposite end, and a sliding valve 53 opposite the radial valve. This creates a valve system configured to provide direct contact to be made between the fluid pumped into the well through the drill string 13, in both directions of the descending flow (radially and axially). In some embodiments, the axial valve 51 and the radial valve 52 may be throttle valves, possibly preloaded with springs, which are closed in a rest position.

[0031] To achieve this, a controller may begin to close valve VI and apply pressure to a chamber 46 inside the circulation coupler 40 by opening valve V2. Referring to FIGURES 3 and 5, the increased pressure of the drilling mud inside the chamber 46 opens a sliding valve 53 in the constant circulation sub 50 so that drilling mud begins to flow into the drill string through the sliding valve 53 and the radial valve 52. As valve VI is fully closed and valve V2 is fully open, the axial valve 51 of the constant circulation sub 50 closes so that the top drive 20 may be disconnected from the stump 19 of the drill string. The drill string may continue to be rotated via the rotary table 18.

[0032] When drilling mud is no longer being supplied to the top drive 20, the top drive 20 is disconnected from the stump 19 of the drilling string 13 and another stand of drill pipe 14 is made up to the top drive 20. While the top drive 20 is disconnected from the drill string 13, the rotary table 18 may continue to turn the drill string 13 while drilling mud is supplied to the drill string 13 via the circulation coupler 40. The new stand of drill pipe 14 may then be made up to the stump 19 of the drill string 13. Once the new stand of drill pipe 14 is connected to and becomes part of the drill string 13, the drill string 13 may continue to be rotated via the rotary table 18 or the top drive 20. The drill string 13 may be lifted by the top drive 20 and the slips 17 released. The operator may then decrease a supply of drilling mud to the circulation coupler 40 while a supply of drilling mud to the top drive 20 is increased, so as to maintain a constant circulation while the supply is shifted from the circulation coupler 40 to the top drive 20. Drilling mud may continue to be circulated through the drill string 13 by opening valve VI to supply drilling mud to the top drive 20, while V2 is partially closed to reduce fluid flow to the circulation coupler 40. As drilling mud begins to flow down through the internal bore of the constant circulation sub 50, the axial valve 51 will open and the radial valve 52 will close. Valve V3 is opened to allow the drilling mud in the circulation coupler 40, rotary hose 35 and floor pipe 34 to drain back into the retention tank 38. As the pressure is relieved from the chamber 46 in the circulation coupler 40, the drill string 13 may continue to be rotated and lowered to continue drilling the well bore 21. The drill string 13 slides down through the circulation coupler 40 during drilling operations until a new stand of drill pipe 14 is to be added to the drill string 13 and the process is repeated. Both the top drive 20 and the rotary table 18 may rotate the drill string 13 as circulation is shifted from the circulation coupler 40 to the top drive 20.

[0033] When drill string 13 is tripped out of the well bore 21, a similar process is followed, in reverse order, to allow constant circulation of drilling mud and constant rotation of the drill string 13.

[0034] In the embodiment shown in FIGURE 2, the circulation coupler 40 is supported by an arm 41.

However, in other embodiments, the circulation coupler may be mounted on a blow-out preventer (BOP) stack in a modular fashion. In other embodiments, the circulation coupler 40 may be integral with a blow-out preventer (BOP) stack. In still further embodiments, the circulation coupler 40 may be mounted in a marine riser above a diverter or rotating control device. In still further embodiments, the circulation coupler 40 may be mounted anywhere in a drilling system to enable constant rotation of the drill string and constant circulation of drilling mud through the drill string. In some embodiments, the arm 41 is used to move the circulation coupler into engagement with the constant circulation sub 50.

[0035] The system of FIGURE 2 may provide an MWD system for constant reception of MWD signals during all aspects of the drilling operation, including tripping. One or more pressure transducers 67 located on the standpipe 32 generate signals that are representative of variations in the pressure of the mud. The outputs of the pressure transducers 67 can be digitized in analog-to-digital converters and processed by a signal processing module 68, which recovers the symbols from the pressure variations and then sends data recovered from the symbols to a computer 69 where the transmitted information can be accessed by the drilling operators. These stand pipe transducers 67 receive MWD signals when the top drive 20 is connected to the drill string 13 and drilling mud is being supplied through the stand pipe 32. One or more pressure transducers 70 are also located in or on the circulation coupler 40. In some embodiments, the pressure transducer 70 may be located in the chamber 46.

[0036] These circulation coupler transducers 70 similarly generate signals that are representative of variations in the pressure of the mud. The outputs of the circulation coupler transducers 70 can also be digitized in analog-to-digital converters and processed by the signal processing module 68, which recovers the symbols from the pressure variations and then sends data recovered from the symbols to the computer 69 where the transmitted information can be accessed by the drilling operators. These circulation coupler transducers 70 receive MWD signals when the top drive 20 is disconnected from the drill string 13 and drilling mud is being supplied through the floor pipe 34. During tripping operations, there are times when drilling mud is supplied through both the floor pipe 34 and the stand pipe 32, When that is the case, MWD signals may be received simultaneously by the circulation coupler transducers 70 and the stand pipe transducers 67.

[0037] FIGURE 4 shows another embodiment of a MWD system for constant reception of MWD signals during all aspects of the drilling operation, including tripping. One or more pressure transducers 67 are located on or in the diverter manifold 31. The transducers 67 generate signals that are representative of variations in the pressure of the mud. The outputs of the pressure transducers 67 can be digitized in analog-to-digital converters and processed by a signal processing module 68, which recovers the symbols from the pressure variations and then sends data recovered from the symbols to a computer 69 where the transmitted information can be accessed by the drilling operators. Because the diverter manifold 3 1 supplies drilling mud to the top drive 20 when the valve VI is open, transducers 67 in the diverter manifold 3 1 receive MWD signals when the top drive 20 is connected to the drill string 13 and drilling mud is being supplied through the stand pipe 32. Similarly, because the diverter manifold 3 1 supplies drilling mud to the circulation coupler 40 when the valve V2 is open, transducers 67 in the diverter manifold similarly generate signals that are representative of variations in the pressure of the mud when the top drive 20 is disconnected from the drill string 13 and drilling mud is being supplied through the floor pipe 34, During tripping operations, there are times when drilling mud is supplied through both the floor pipe 34 and the stand pipe 32, When that is the case, MWD signals may be received simultaneously by the transducers 67 in the diverter manifold 31.

[0038] Embodiments of this disclosure include a system including at least one sensor on a drill string proximate a drill bit for measuring a parameter, a transmitter of parameter measurements on the drill string proximate the at least one sensor, a first transducer positioned to receive transmitted parameter measurements in drilling mud in at least one of a stand pipe, a rotary hose in fluid communication with a stand pipe, and a top drive in fluid communication with the stand pipe, and a second transducer positioned to receive transmitted parameter measurements in drilling mud in at least one of a floor pipe, a rotary hose in fluid communication with the floor pipe, and a circulation coupler in fluid communication with the floor pipe. In some embodiments, the second transducer is positioned in a chamber of the circulation coupler. The system may also include a manifold to direct drilling mud to the top drive and/or the circulation coupler. In some embodiments, the manifold diverts the drilling mud between the first transducer to the second transducer. In some embodiments, they system includes a controller to operate a plurality of valves configured to divert the drilling mud between the first transducer and the second transducer. In other embodiments, the first transducer is positioned in the stand pipe and the second transducer is positioned in the circulation coupler. In an alternate embodiment, the system may include a third transducer positioned to receive transmitted parameter measurements in drilling mud in at least one of a stand pipe, a rotary hose in fluid communication with a stand pipe, and a top drive in fluid communication with the stand pipe, wherein the first transducer and the third transducer are in different locations. The circulation coupler may be coupled to a circulation sub coupled to a drill string. In some embodiments, the circulation sub includes at least one valve in fluid communication with the rotary hose in fluid communication with the floor pipe.

[0039] Another embodiment disclosed includes a system including at least one sensor on a drill string proximate a drill bit for measuring a parameter, a transmitter of parameter measurements on the drill string proximate the at least one sensor, a transducer positioned in a manifold to receive transmitted parameter measurements in drilling mud, the manifold in fluid communication with both (i) at least one of a stand pipe, a rotary hose in fluid communication with a stand pipe, and a top drive in fluid communication with the stand pipe, and (ii) at least one of a floor pipe, a rotary hose in fluid communication with the floor pipe, and a circulation coupler in fluid communication with the floor pipe. In some embodiments, the manifold is configured to receive drilling mud from a mud tank and distribute the drilling mud to the stand pipe, the floor pipe, and back to the mud tank. The system may also include a controller to vary the flow of drilling mud to the stand pipe, the floor pipe, and back to the mud tank. In other embodiments, the system may include a plurality of valves to vary the flow of drilling mud to the stand pipe, the floor pipe, and back to the mud tank.

[0040] Embodiments also include a method including measuring a drilling mud parameter within a drill string, transmitting the parameter measurements through the drilling mud, receiving the transmitted parameter measurements in the drilling mud at a location outside the drill string, wherein the receiving occurs in at least one of a diverter manifold, a stand pipe, a rotary hose in fluid communication with a stand pipe, a top drive in fluid communication with the stand pipe, a floor pipe, a rotary hose in fluid communication with the floor pipe, and a circulation coupler in fluid communication with the floor pipe. The method may also include tripping the drill string while circulating the drilling mud through the stand pipe, the rotary hose in fluid communication with the stand pipe, and the top drive in fluid communication with the stand pipe and the drill string. In some embodiments, the receiving occurs in at least one of the stand pipe, the rotary hose in fluid communication with a stand pipe, and the top drive in fluid communication with the stand pipe. In other embodiments, the method may include tripping the drill string while circulating the drilling mud through the floor pipe, the rotary hose in fluid communication with the floor pipe, and the circulation coupler in fluid communication with the floor pipe. The receiving may occur in at least one of the floor pipe, the rotary hose in fluid communication with the floor pipe, and the circulation coupler in fluid communication with the floor pipe. In some embodiments, the method may include tripping the drill string while continuously circulating the drilling mud through the diverter manifold. In some embodiments, the receiving occurs in the diverter manifold.

[0041] Although the preceding has been described herein with reference to particular means, materials, and embodiments, it is not intended to be limited to the particulars herein; rather, it extends to all functionally equivalent structures, methods, and uses such as are within the scope of the appended claims.