Patent Application
20160017659
Oil wells are created by drilling a hole into the earth using a drilling rig that rotates a drill string (e.g., drill pipe) having a drill bit attached thereto. The drill bit, aided by the weight of pipes (e.g., drill collars) cuts into rock within the earth. Drilling fluid (e.g., mud) is pumped into the drill pipe and exits at the drill bit. The drilling fluid may be used to cool the bit, lift rock cuttings to the surface, at least partially prevent destabilization of the rock in the wellbore, and/or at least partially overcome the pressure of fluids inside the rock so that the fluids do not enter the wellbore. Rotary steerable systems (RSS) can be used for directional drilling. These systems employ down hole equipment that responds to commands (e.g., from surface equipment) and steers into a desired direction. For example, pistons may be used to generate force against a borehole wall or to cause angular displacement of one steerable system component with respect to another to cause a drill bit to move in the desired direction of deviation.
Aspects of the disclosure can relate to a down hole drill assembly that includes an input shaft coupled with a prime mover to be driven at a nominal uncontrolled rotational speed, and an output shaft coupled with the input shaft to drive a rotary mechanism. The input shaft can be driven by drilling fluid or another fluid. The down hole drill assembly also includes a drive mechanism mechanically coupling the input shaft to the output shaft to drive the rotary mechanism at a controlled rotational speed. The down hole drill assembly further includes a secondary input mechanically coupled with the drive mechanism, where the secondary input is driven as a control input to drive the rotary mechanism at the controlled rotational speed.
Other aspects of the disclosure can relate to a method that includes driving an input shaft coupled with a prime mover at a nominal uncontrolled rotational speed. The method also includes driving a rotary mechanism with an output shaft coupled with the input shaft. The method further includes mechanically coupling the input shaft to the output shaft with a drive mechanism to drive the rotary mechanism at a controlled rotational speed, and mechanically coupling a secondary input with the drive mechanism. The method also includes driving the secondary input as a control input to drive the rotary mechanism at the controlled rotational speed.
Also, aspects of the disclosure can relate to a system that includes an input shaft to be driven at a nominal uncontrolled rotational speed by fluid flow, and an output shaft coupled with the input shaft to drive a rotary mechanism. The system also includes a drive mechanism mechanically coupling the input shaft to the output shaft to drive the rotary mechanism at a controlled rotational speed. The system further includes a secondary input mechanically coupled with the drive mechanism, where the secondary input is driven as a control input to drive the rotary mechanism at the controlled rotational speed.
This summary is provided to introduce a selection of concepts that are further described below in the detailed description. This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used as an aid in limiting the scope of the claimed subject matter.
Embodiments of an actively controlled rotary steerable drilling system are described with reference to the following figures. The same numbers are used throughout the figures to reference like features and components.
A bottom hole assembly (BHA) 116 is suspended at the end of the drill string 104. The bottom hole assembly 116 includes a drill bit 118 at its lower end. In embodiments of the disclosure, the drill string 104 includes a number of drill pipes 120 that extend the bottom hole assembly 116 and the drill bit 118 into subterranean formations. Drilling fluid (e.g., mud) 122 is stored in a tank and/or a pit 124 formed at the wellsite. The drilling fluid can be water-based, oil-based, and so on. A pump 126 displaces the drilling fluid 122 to an interior passage of the drill string 104 via, for example, a port in the rotary swivel 114, causing the drilling fluid 122 to flow downwardly through the drill string 104 as indicated by directional arrow 128. The drilling fluid 122 exits the drill string 104 via ports (e.g., courses, nozzles) in the drill bit 118, and then circulates upwardly through the annulus region between the outside of the drill string 104 and the wall of the borehole 102, as indicated by directional arrows 130. In this manner, the drilling fluid 122 cools and lubricates the drill bit 118 and carries drill cuttings generated by the drill bit 118 up to the surface (e.g., as the drilling fluid 122 is returned to the pit 124 for recirculation).
In some embodiments, the bottom hole assembly 116 includes a logging-while-drilling (LWD) module 132, a measuring-while-drilling (MWD) module 134, a rotary steerable drilling system 136, a motor, and so forth (e.g., in addition to the drill bit 118). The logging-while-drilling module 132 can be housed in a drill collar and can contain one or a number of logging tools. It should also be noted that more than one LWD module and/or MWD module can be employed (e.g. as represented by another logging-while-drilling module 138). In embodiments of the disclosure, the logging-while drilling modules 132 and/or 138 include capabilities for measuring, processing, and storing information, as well as for communicating with surface equipment, and so forth.
The measuring-while-drilling module 134 can also be housed in a drill collar, and can contain one or more devices for measuring characteristics of the drill string 104 and drill bit 118. The measuring-while-drilling module 134 can also include components for generating electrical power for the down hole equipment. This can include a mud turbine generator (also referred to as a “mud motor”) powered by the flow of the drilling fluid 122. However, this configuration is provided by way of example and is not meant to limit the present disclosure. In other embodiments, other power and/or battery systems can be employed. The measuring-while-drilling module 134 can include one or more of the following measuring devices: a weight-on-bit measuring device, a torque measuring device, a vibration measuring device, a shock measuring device, a stick slip measuring device, a direction measuring device, an inclination measuring device, and so on.
In embodiments of the disclosure, the wellsite system 100 is used with controlled steering or directional drilling. For example, the rotary steerable drilling system 136 is used for directional drilling. As used herein, the term “directional drilling” describes intentional deviation of the wellbore from the path it would naturally take. Thus, directional drilling refers to steering the drill string 104 so that it travels in a desired direction. In some embodiments, directional drilling is used for offshore drilling (e.g., where multiple wells are drilled from a single platform). In other embodiments, directional drilling enables horizontal drilling through a reservoir, which enables a longer length of the wellbore to traverse the reservoir, increasing the production rate from the well. Further, directional drilling may be used in vertical drilling operations. For example, the drill bit 118 may veer off of a planned drilling trajectory because of the unpredictable nature of the formations being penetrated or the varying forces that the drill bit 118 experiences. When such deviation occurs, the wellsite system 100 may be used to guide the drill bit 118 back on course.
The drill assembly 200 includes a body 202 for receiving a flow of drilling fluid. The body 202 comprises one or more crushing and/or cutting implements, such as conical cutters and/or bit cones having spiked teeth (e.g., in the manner of a roller-cone bit). In this configuration, as the drill string is rotated, the bit cones roll along the bottom of the borehole in a circular motion. As they roll, new teeth come in contact with the bottom of the borehole, crushing the rock immediately below and around the bit tooth. As the cone continues to roll, the tooth then lifts off the bottom of the hole and a high-velocity drilling fluid jet strikes the crushed rock chips to remove them from the bottom of the borehole and up the annulus. As this occurs, another tooth makes contact with the bottom of the borehole and creates new rock chips. In this manner, the process of chipping the rock and removing the small rock chips with the fluid jets is continuous. The teeth intermesh on the cones, which helps clean the cones and enables larger teeth to be used. A drill assembly 200 comprising a conical cutter can be implemented as a steel milled-tooth bit, a carbide insert bit, and so forth. However, roller-cone bits are provided by way of example and are not meant to limit the present disclosure. In other embodiments, a drill assembly 200 is configured differently. For example, the body 202 of the bit comprises one or more polycrystalline diamond compact (PDC) cutters that shear rock with a continuous scraping motion.
In embodiments of the disclosure, the body 202 of the drill assembly 200 can define one or more nozzles that allow the drilling fluid to exit the body 202 (e.g., proximate to the crushing and/or cutting implements). The nozzles allow drilling fluid pumped through, for example, a drill string to exit the body 202. For example, as discussed with reference to
The body 202 houses components for actuating a rotary mechanism included with the down hole equipment (e.g., a rotary valve used for directionally controlling a biasing unit of the rotary steerable drilling system 136, another mechanism involved in the directional control of a bias unit, and so forth). For example, the body 202 houses a primary input mechanism, such as a mud turbine 204 powered by the flow of the drilling fluid 122, a motor 205 (e.g., an alternating current (AC) induction motor), or another prime mover. The primary input mechanism comprises an input shaft 206, which can be driven by a fluid flow, such as the flow of the drilling fluid 122. In other embodiments, the input shaft 206 can be driven by the motor 205, or by another prime mover. The drill assembly 200 also includes an output shaft 208 coupled with the input shaft 206 to drive a rotary mechanism (e.g., a rotary valve of RSS equipment).
Further, the drill assembly 200 includes a drive mechanism 212 mechanically coupling the input shaft 206 to the output shaft 208. In embodiments of the disclosure, the drill assembly 200 is configured so that the drive mechanism 212 is operable to drive the rotary mechanism using a variable transmission ratio such that the input shaft 206 can run independently or at least substantially independently at one or more nominal angular speeds selected for the hydraulic mud motor/turbine or prime mover, while the output shaft 208 can run at a controlled angular speed such that it can maintain a constant geostationary angular position relative to a geostationary coordinate system, even with external disturbances, such as varying collar speed, mud weight, mud flow and so forth.
For rotary steerable drilling system equipment, the actuation of a biasing mechanism can be driven by a rotary valve, which remains fixed with respect to a geostationary coordinate system. This can be accomplished using a high speed, high torque servo mechanism. With a drilling system that implements a rotating sleeve tool, the torque used to rotate the valve can be furnished directly from an impeller, such as the impeller of a mud turbine rotary mechanism. Depending upon the flow of drilling fluid and the direction the drilling equipment is aimed, systems called “torquers” can be used to break the rotation of a control unit. However, this technique may generate heat due to high induction current in the torquers (referred to as “magnetic friction”). With a drilling system that does not implement rotating sleeve tools, the energy used to actuate the rotary valve can be supplied by a turbine power rotary mechanism, which can convert hydraulic power from the flow of drilling fluid into electricity, which is supplied to a servo motor. However, the energy needed to actuate the valve can be in the range of hundreds of Watts, and this configuration can occupy a large volume of space within the drilling equipment (e.g., using a power rotary mechanism, power converter electronics, a high power control system, and a control valve actuator).
In some embodiments, the nominal torque output of the primary input mechanism is supplied to a drive mechanism 212 that comprises a continuously variable transmission (CVT) 210, a constant speed drive (CSD) 211, a combination of a continuously variable transmission 210 and a constant speed drive 211, and so forth. The drive mechanism 212 mechanically couples the input shaft 206 to the output shaft 208 and operates to drive the rotary valve. In this manner, the input shaft 206 of the primary input mechanism is not directly actuating the rotary valve. Instead, the mechanical drive mechanism 212 modifies the rotation speed of the rotary valve using a secondary input 214 (e.g., an electric motor, a hydraulic motor, and so on). The secondary input 214 is mechanically coupled with the drive mechanism 212 and can be driven at a controlled (e.g., variable) input speed. This technique provides control actuation input for modifying the angular velocity of the rotary valve (e.g., according to a control system and/or position feedback loops). In this manner, the rotary steerable system can drill in a desired direction, even in suboptimal conditions for the primary input mechanism.
As described herein, the amount of electrical power used to drive an RSS biasing mechanism can be reduced (e.g., with respect to a drilling system where the torque used to rotate the valve is furnished directly from an impeller, or a drilling system where the energy used to actuate the rotary valve is supplied by a turbine power rotary mechanism). Further, the electrical power supply requirements and/or the control electronics can be simpler. In this manner, the drill assembly 200 can provide increased power efficiency and/or reduced heat dissipation (e.g., using the operating principles described herein based upon energy conversion from speed to torque and/or from torque to speed). Further, in a nominal condition for the primary input mechanism, a simplified control method may be used (e.g., without driving, where the valve rotates at or near the angular velocity used to aim the RSS in the desired direction).
The primary input mechanism (e.g., the motor 205, the mud turbine 204, or another prime mover), does not necessarily provide control to the rotary valve. Instead, direct servo control can be applied by actuation of the continuously variable transmission 210 and/or the constant speed drive 211. In this manner, the primary input mechanism can use a simplified control architecture such as open loop control to operate the output shaft 208 at a controlled speed. For example, the continuously variable transmission ratio can be actuated without direct feedback measurement (e.g., using indirect measurement of the speed of the output shaft 208). In some embodiments, the continuously variable transmission ratio can be actuated with a stepper motor or scalar AC induction motor control. In this manner, the output shaft 208 can be maintained at a controlled geostationary position, while the input shaft 206 can rotate at an uncontrolled nominal speed, which can be subject to external disturbances and/or not under direct control. In some embodiments, an actuator for the continuously variable transmission 210 and/or the constant speed drive 211 can provide direct feedback controlled actuation for geo-positioning of the rotary valve.
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A system implementing a drill assembly 200, including some or all of its components, can operate under computer control. For example, a processor can be included with or in a system to control the components and functions of systems described herein using software, firmware, hardware (e.g., fixed logic circuitry), manual processing, or a combination thereof. The terms “controller,” “functionality,” “service,” and “logic” as used herein generally represent software, firmware, hardware, or a combination of software, firmware, or hardware in conjunction with controlling the systems. In the case of a software implementation, the module, functionality, or logic represents program code that performs specified tasks when executed on a processor (e.g., central processing unit (CPU) or CPUs). The program code can be stored in one or more computer-readable memory devices (e.g., internal memory and/or one or more tangible media), and so on. The structures, functions, approaches, and techniques described herein can be implemented on a variety of commercial computing platforms having a variety of processors.
The drill assembly 200 can be coupled with a controller (e.g., controller 218) for controlling the output of the drive mechanism 212. The controller can include a processor, a memory, and a communications interface. The processor provides processing functionality for the controller and can include any number of processors, micro-controllers, or other processing systems, and resident or external memory for storing data and other information accessed or generated by the controller. The processor can execute one or more software programs that implement techniques described herein. The processor is not limited by the materials from which it is formed or the processing mechanisms employed therein and, as such, can be implemented via semiconductor(s) and/or transistors (e.g., using electronic integrated circuit (IC) components), and so forth.
The memory is an example of tangible, computer-readable storage medium that provides storage functionality to store various data associated with operation of the controller, such as software programs and/or code segments, or other data to instruct the processor, and possibly other components of the controller, to perform the functionality described herein. Thus, the memory can store data, such as a program of instructions for operating the system (including its components), and so forth. It should be noted that while a single memory is described, a wide variety of types and combinations of memory (e.g., tangible, non-transitory memory) can be employed. The memory can be integral with the processor, can comprise stand-alone memory, or can be a combination of both. The memory can include, but is not necessarily limited to: removable and non-removable memory components, such as random-access memory (RAM), read-only memory (ROM), flash memory (e.g., a secure digital (SD) memory card, a mini-SD memory card, and/or a micro-SD memory card), magnetic memory, optical memory, universal serial bus (USB) memory devices, hard disk memory, external memory, and so forth.
The communications interface is operatively configured to communicate with components of the system. For example, the communications interface can be configured to transmit data for storage in the system, retrieve data from storage in the system, and so forth. The communications interface is also communicatively coupled with the processor to facilitate data transfer between components of the system and the processor (e.g., for communicating inputs to the processor received from a device communicatively coupled with the controller). It should be noted that while the communications interface is described as a component of a controller, one or more components of the communications interface can be implemented as external components communicatively coupled to the system via a wired and/or wireless connection. The system can also comprise and/or connect to one or more input/output (I/O) devices (e.g., via the communications interface), including, but not necessarily limited to: a display, a mouse, a touchpad, a keyboard, and so on.
The communications interface and/or the processor can be configured to communicate with a variety of different networks, including, but not necessarily limited to: a wide-area cellular telephone network, such as a 3G cellular network, a 4G cellular network, or a global system for mobile communications (GSM) network; a wireless computer communications network, such as a WiFi network (e.g., a wireless local area network (WLAN) operated using IEEE 802.11 network standards); an internet; the Internet; a wide area network (WAN); a local area network (LAN); a personal area network (PAN) (e.g., a wireless personal area network (WPAN) operated using IEEE 802.15 network standards); a public telephone network; an extranet; an intranet; and so on. However, this list is provided by way of example and is not meant to limit the present disclosure. Further, the communications interface can be configured to communicate with a single network or multiple networks across different access points.
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Although only a few example embodiments have been described in detail above, those skilled in the art will readily appreciate that many modifications are possible in the example embodiments without materially departing from an actively controlled rotary steerable drilling system. Features shown in individual embodiments referred to above may be used together in combinations other than those which have been shown and described specifically. Accordingly, all such modifications are intended to be included within the scope of this disclosure as defined in the following claims. In the claims, means-plus-function clauses are intended to cover the structures described herein as performing the recited function and not only structural equivalents, but also equivalent structures. Thus, although a nail and a screw may not be structural equivalents in that a nail employs a cylindrical surface to secure wooden parts together, whereas a screw employs a helical surface, in the environment of fastening wooden parts, a nail and a screw may be equivalent structures. It is the express intention of the applicant not to invoke 35 U.S.C. §112, paragraph 6 for any limitations of any of the claims herein, except for those in which the claim expressly uses the words ‘means for’ together with an associated function.
