The present disclosure relates generally to downhole motors, and specifically to wired communication in downhole motors.
When drilling a wellbore, it may be desirable to measure one or more parameters from within the wellbore near the drill bit. Traditionally, one or more sensors are positioned in a nearbit sub positioned between the drill bit and the rest of the downhole assembly. However, the near-bit sub may add length to the lower end of the downhole motor and may therefore reduce the ability of the downhole assembly to be steered by, for example and without limitation, a bent sub or bent housing. Typically, sensors in the near-bit sub use a wireless connection to transmit information to a measurement while drilling assembly positioned above the downhole motor. However, the use of electromagnetic transmission across the mud motor may require a large amount of power, necessitating the use of batteries and special antennae, which may increase the cost and reliability of the downhole assembly.
The present disclosure provides for a bottomhole assembly. The bottomhole assembly may include a downhole motor including a rotor and a stator. The rotor may have a first end and a second end. The bottomhole assembly may include a bearing assembly including a bearing housing and a bearing mandrel. The bearing mandrel may have a first end and a second end. The bottomhole assembly may include a transmission shaft having a first end and a second end. The first end of the transmission shaft may be mechanically coupled to the first end of the rotor. The second end of the transmission shaft may be mechanically coupled to the first end of the bearing mandrel. The bottomhole assembly may include a sensor positioned at the second end of the transmission shaft. The bottomhole assembly may include a conductor positioned within the transmission shaft and the rotor, the conductor extending from the sensor to the second end of the rotor.
The present disclosure is best understood from the following detailed description when read with the accompanying figures. It is emphasized that, in accordance with the standard practice in the industry, various features are not drawn to scale. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion.
It is to be understood that the following disclosure provides many different embodiments, or examples, for implementing different features of various embodiments. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed.
In some embodiments, BHA 100 may include bearing assembly 103. Downhole motor 101 may be used to rotate one or more components of BHA 100 in order to rotate drill bit 15. Downhole motor 101 may include rotor 105 and stator 107. Rotor 105 may be positioned within stator 107 and may rotate relative to stator 107 in response to the flow of drilling fluid through stator 107. In some embodiments, rotating components of BHA 100 may include, without limitation, drill bit 15, bearing mandrel 109, transmission shaft 111, rotor catch shaft 113, flex shaft 115, and one or more components of communication package 117.
In some embodiments, bearing mandrel 109 may be positioned within bearing housing 119 in order to form bearing assembly 103. In some embodiments, bearing housing 119 may mechanically couple to stator 107. In some embodiments, bearing housing 119 may mechanically couple to stator 107 through bent housing 121. In such an embodiment, bent housing 121 may be configured such that bearing housing 119 extends at an angle to stator 107 allowing, for example and without limitation, a wellbore formed using BHA 100 to be steered or otherwise drilled at an angle.
In some embodiments, as depicted in
In some embodiments, BHA 100 may include rotor catch assembly 123. Rotor catch assembly 123 may include top sub 125 also known as a rotor catch housing and rotor catch shaft 113. Rotor catch shaft 113 may mechanically couple at a first end 113a to the second end 105b of rotor 105. Rotor catch assembly 123 may, for example and without limitation, retain rotor 105 within stator 107 in the case of a mechanical failure of one or more components of BHA 100.
In some embodiments, second end 113b of rotor catch shaft 113 may mechanically couple to a first end 115a of flex shaft 115. Flex shaft 115 may mechanically couple at its second end 115b to communications package 117. In some embodiments, second end 113b of rotor catch shaft 113 may mechanically couple to communications package 117 directly, without using a flex shaft 115 or a bearing. In some embodiments, communications package 117 may include one or more of batteries, electronics, collectors, and coil transceivers as further discussed herein below. As used herein, “coil transceiver” is not intended to require capability of both transmission and reception, and may include one or both of a transmitter and receiver. In some embodiments, flex shaft 115 may mechanically couple the eccentric rotary motion of rotor 105 and concentric rotation of one or more components of communications package 117.
In some embodiments, one or more components of communications package 117 and MWD assembly 102 may be positioned within MWD sub housing 127. MWD sub housing 127 may be mechanically coupled to top sub 125.
In some embodiments, as depicted in
In some embodiments, as depicted in
In some embodiments, as depicted in
In other embodiments, as depicted in
In some embodiments, as depicted in
In some embodiments, as depicted in
In some embodiments, information about the operation of BHA 100 may be transmitted to the surface via mud pulse telemetry. In some embodiments, temperature difference, temperature gradient, and other drilling dynamics information may be classified into different severity levels, for example, 4 to 8 severity levels indicative of a measured condition. As a non-limiting example, in embodiments in which 2-bit severity levels (4 levels) are used, a temperature difference may be coded as Level 1 which may be between 0 and 2 degrees centigrade, Level 2 between 2 and 4 degrees centigrade, Level 3 between 4 and 6 degrees centigrade, and Level 4 above 6 degrees centigrade. Similarly, downhole acceleration events or shocks may be coded as Level 1 (no shock) between 0 and 10 g, Level 2 (low) between 10 and 40 g, Level 3 (medium) between 40 and 100 g, and Level 4 (high) above 100 g. As another example, high-frequency torsional oscillation (HFTO) may be detected with tangential acceleration measurement with an expected frequency range, for example, between 100 and 800 Hz. By applying a digital band pass, analog band-pass, high-pass filter, or a combination thereof on a tangential accelerometer, downhole HFTO events may be coded as Level 1 (no HFTO) between 0 and 10 g, Level 2 (low HFTO) between 10 and 40 g, Level 3 (medium HFTO) between 40 and 100 g, and Level 4 (high HFTO) above 100 g.
Rock mechanics parameters (e.g. Young's modulus, Poisson's ratio, compressive strength, and Fractures) may be detected with tri-axial high-frequency acceleration measurement with an expected frequency range, for example, between 100 and 1000 Hz, as described, for example in SPWLA 2017—“A Novel Technique for Measuring (Not Calculating) Young's Modulus, Poisson's Ratio and Fractures Downhole: A Bakken Case Study”. By applying a digital band-pass, analog band-pass, digital high-pass filters, analog high-pass filters, or a combination thereof on the at least one accelerometer, downhole fractures may be coded as Level 1 (no fractures) between 0 and 10, Level 2 (low) between 10 and 40, Level 3 (medium) between 40 and 100, and Level 4 (high) above 100 (the numbers are without units, but correlated to the number of fractures).
With a limited mud pulse telemetry bandwidth, severity level classification may operate as a data compression method. In some embodiments, sensor pocket 139 may be formed at second end 111b of transmission shaft 111 behind one or more components of universal joint 110 such as thrust cap 141. In some embodiments, sensor pocket 139 may include, for example and without limitation, sensor 137, battery 138, electronics 140, and connector 142 for connecting one or more of sensor 137, battery 138, and electronics 140 to conductor 135. In some embodiments, one or more sensors may be integrated into communications package 117. The integrated sensors may include solid-state gyros, low-g accelerometers, high-g accelerometers, and temperature sensors. The gyro sensors may be used to detect rotation on/off events with a simple RPM threshold, such as 10 RPM. The integrated gyro sensor may be used to decode rotation-speed-modulation downlinks by using, for example, the method disclosed in US Pat App. 20170254190, which is incorporated herein by reference. The low-g and high-g accelerometers may be used to calculate inclinations and detect inclination on/off events with a simple inclination threshold, such as 45 degrees. The low-g and high-g accelerometers may detect flow on/off event with a simple vibration threshold, such as +/−1 G peak accelerations and/or with a simple vibration variance threshold, such as +/−0.2 G accelerations.
In some embodiments, conductors 135 may be made up of multiple lengths of conductor, each length passing through one component of BHA 100. In some such embodiments, one or more connector assemblies 143 may be positioned between the adjacent components, such as connector assembly 143 positioned between first end 111a of transmission shaft 111 and first end 105a of rotor 105 as depicted in
In some embodiments, as depicted in
In some embodiments, male connector 145 may include plug 155 that, when male connector 145 is engaged with female connector 147, may enter and electrically couple with socket 157 formed in female connector 147. In some embodiments, plug 155 may be electrically coupled to second conductor length 135b through compression assembly 159. In some embodiments, compression assembly 159 may include pressure plate 161 mechanically and electrically coupled to plug 155 biased against rotor conductor rod 151 by spring 163. Spring 163 may, for example and without limitation, damp compressive forces between plug 155 and socket 157 as connector assembly 143 is made up, reducing the possibility of damage to BHA 100.
In some embodiments, conductors 135 may electrically couple sensor 137 with communications package 117. Communications package 117 may, in some embodiments, include a power supply for powering any electronics positioned therein and for providing power to sensor 137. The power supply may include, for example and without limitation, one or more batteries. In some embodiments, communications package 117 may transmit data from sensor 137 to MWD assembly 102 using coil transceiver 133 to wirelessly transmit the data to the corresponding coil positioned in MWD assembly 102. Communications package 117 may receive data from MWD assembly 102 to sensor 137 using coil transceiver 133. In such an embodiment, the communication may be full-duplex or semi-full duplex (bi-directional). The coil-to-coil distance between coil transceiver 133 and the coil of MWD assembly 102 may be between 1 inch and 10 feet. In some embodiments, the coil-to-coil communications may be achieved with inductive and/or capacitive coupling or electro-magnetic transmission/reception. The coil-to-coil communications frequency may be between 20 Hz and 200 MHz. Any known modulation techniques may be utilized for the coil-to-coil communications including, for example and without limitation, amplitude, frequency, and phase modulation. Conventional digital modulation schemes, for example, including QAM, DSL, ADSL, TDMA, FDMA, ASK, FSK, BPSK, QPSK and the like, may also be utilized. In some embodiments, MWD assembly 102 may include one or more transmitters/receivers for conveying information from sensors 137 including, for example and without limitation, one or more of mud pulse telemetry, EM (electro-magnetic) telemetry, acoustic telemetry, wired drill pipe, or a combination thereof (e.g. dual telemetry using both mud pulse and EM) or any other transmitter to the surface. In some embodiments that utilize bidirectional communication, on/off information from MWD assembly 102, such as for example and without limitation flow, pressure or vibration data, may be transmitted to sensor 137 and information such as inclination, gravity toolface, RPM, temperature, shock and vibration, HFTO, and rock mechanics (including, but not limited to Young's modulus, Poisson's ratio, compressive strength, and fractures) information from sensor 137 may be transmitted to MWD assembly 102.
The configuration described herein may be advantageous for a cost-effective implementation of accurate, real-time, near-bit inclination measurement, but is not limited in this regard.
The foregoing outlines features of several embodiments so that a person of ordinary skill in the art may better understand the aspects of the present disclosure. Such features may be replaced by any one of numerous equivalent alternatives, only some of which are disclosed herein. One of ordinary skill in the art should appreciate that they may readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. One of ordinary skill in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the present disclosure and that they may make various changes, substitutions, and alterations herein without departing from the spirit and scope of the present disclosure.
This application is a nonprovisional application that claims priority from U.S. provisional application No. 62/418,495, filed Nov. 7, 2016.
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62418495 | Nov 2016 | US |