The present invention relates to the field of workover rigs used for oil & gas operations, and in particular to a system and technique for retrofitting a mechanical workover rig to a hybrid electric and mechanical drive.
Workover rigs have been used for many decades in oil & gas operations for wellbore intervention, workover operations, and eventual plugging and abandonment of wellbores. They vary in scale and specific components but generally consist of a hoisting system, a circulation system, a rotation system, a power system, and a well control system. The prime movers within the power system are generally internal combustion engines reliant on diesel fuel.
As greenhouse gas emissions have come under increased scrutiny, a demand for cleaner oilfield operations has arisen with equipment powered by electricity rather than hydrocarbons. There do exist certain large rigs which are available in electric drive modes (generally higher horsepower rigs capable of drilling operations as well as workovers). However, there is currently no accepted method to utilize electricity to drive a workover rig's operations due to its mechanically driven nature.
In one general aspect, a method of retrofitting a workover rig to a hybrid electro-mechanical drive comprises removing a prime mover engine of the workover rig; connecting a first electric motor set to a main transmission of the workover rig; connecting a second electric motor set to a drawworks of the workover rig; installing a power control system to intake and distribute power among components of the workover rig, installing a software-driven feedback and control system for the first electric motor set and the second electric motor set; and disconnecting electrical components of the workover rig from an alternator of the workover rig and connecting the electrical components to the power control system.
In a second general aspect, a retrofit kit for a mechanical workover rig to a hybrid electric mechanical drive comprises a first set of electric motors, configured for connection to a main transmission of the mechanical workover rig; a second set of electric motors, configured for connection to a drawworks of the mechanical workover rig; a power control system, configured for controlling electrical power across the mechanical workover rig; a feedback and control software for the first set of electric motors and the second set of electric motors.
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate an implementation of apparatus and methods consistent with the present invention and, together with the detailed description, serve to explain advantages and principles consistent with the invention. In the drawings,
In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the invention. It will be apparent, however, to one skilled in the art that the invention may be practiced without these specific details. In other instances, structure and devices are shown in block diagram form in order to avoid obscuring the invention. References to numbers without subscripts are understood to reference all instances of subscripts corresponding to the referenced number. Moreover, the language used in this disclosure has been principally selected for readability and instructional purposes, and may not have been selected to delineate or circumscribe the inventive subject matter, resort to the claims being necessary to determine such inventive subject matter. Reference in the specification to “one embodiment” or to “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiments is included in at least one embodiment of the invention, and multiple references to “one embodiment” or “an embodiment” should not be understood as necessarily all referring to the same embodiment.
Although some of the following description is written in terms that relate to software or firmware, embodiments can implement the features and functionality described herein in software, firmware, or hardware as desired, including any combination of software, firmware, and hardware. References to daemons, drivers, engines, modules, or routines should not be considered as suggesting a limitation of the embodiment to any type of implementation.
To power the rig via an electric input (e.g., a battery energy storage system or generators), the mechanical system needs modification. On a prior art mechanical rig 100 such as illustrated in
The engine 101 is the main power source (prime mover) on the rig 100 which utilizes diesel fuel and converts chemical energy in the diesel fuel into mechanical energy. The transmission 102 transmits the mechanical energy from the engine 101 to the axles and wheels 104, the drawworks 111, the sand drum 112, hydraulic components 113, and other mechanical components 114 on the rig 100 via a right-angle box 105 and various transmissions, such as drawworks transmission 107 and sand drum transmission 108, a hydraulics unit 109, and gears, chain, pulley systems, etc. 110 that serve as interconnects between the engine 101 and the drawworks 111, sand drum 112, hydraulics components 113, and other mechanical components 114. The transmission 102 is also responsible for speed and torque control. An alternator or generator 103 may also be driven by the engine 101 to provide electricity for electric components 106.
With an electro electro-mechanical workover rig, the need for the engine 101 may be much reduced if not eliminated, depending on the specific design. The retrofitted rig may be mounted on a trailer for the purposes of transportation, in which case the engine 101 may be eliminated altogether, as illustrated in the configuration of
Various embodiments provide a retrofit kit including the elements described below for retrofitting the mechanical workover rig to an electro-mechanical drive rig.
As disclosed below, one or more electric motor(s) may be installed, replacing the pre-existing engine 101. The electric motors will perform a similar functionality to the replaced engine 101 in driving the transmission 102 to power the components on the rig. In the embodiment of
A retrofit of the rig 200 as illustrated in
As illustrated in
A drawworks transmission 107 for the drawworks 111 is typically a variable transmission that typically has four gear ratios: high-torque (high and low speed) and low-torque (high and low speed). The gear is shifted based on the operation currently underway. For example, a tripping operation from the bottom of the hole would have a heavy hook load so a suitable gear ratio might be high-torque low-speed.
A technique for retrofitting the drawworks 111 is illustrated in
An alternate technique that may enhance control and precision is illustrated in
A third, simpler embodiment is illustrated in
To drive the first motor set 201 and the second motor set 215, a power control system 217 may be installed to intake, regulate, and distribute power to the components of the rig 200. The power control system may integrate all the motor controllers for each motor in one place (shown) or may be present as separate units with each motor (not shown). If AC motors are used for the first motor set 201 or the second motor set 215, they may be connected to variable frequency drives (not shown) for speed and torque control. If DC motors are used for the first motor set 201 or the second motor set 215, a controller using thyristors, insulated-gate bipolar transistors (IGBTs), metal-oxide-semiconductor field-effect transistors (MOSFETs), other semiconductors (not shown) may be included as part of the power control system 217. An inverter (not shown) may also be used for the ancillary systems if they are AC electric or hydraulically run.
The electrical components 206 of the rig 200 are disconnected from the alternator or generator 103 (which is driven by the first motor set 201) and powered by directly connecting to the power source and power control system 217 for increased energy efficiency. Optionally, the alternator or generator 103 may be retained and continued to be powered by the first motor set 201 and the electrical components 106 run by the electricity generated by the alternator or generator 103.
Because the rig 200 of
In some embodiments, the alternator or generator 103 may be eliminated, and electrical power provided from the power control system 217 to electric components 106. If the power control system 217 is AC and the electric components 106 are DC, a power converter such as an inverter (not shown) may be used. Alternately, the first motor set 201 may continue to drive an alternator or generator 103 for powering the electrical components 106 of the rig 200.
A computer control 504 that is software-driven may be added to the feedback loop of each of the motor controllers (not shown) for the motor(s) on the rig, that assists in the oil and gas operations. The computer control 504 may be comprised of sensors and algorithmic-based software that assists in controlling acceleration, speeds, maximum allowed tension (force), partial cycling motions to assist in workover operations, and more. The computer control 504 may provide more precise control of the motor than possible with a mechanical transmission. This can improve operations by, for example, helping to minimize the occurrence of broken strings in a dilapidated wellbore situation that result in expensive fishing jobs.
Capacitors and flywheels (not shown) may be included to store excess energy within a regenerative braking system. These systems can be used to power the motors, reducing energy costs and further increasing operational efficiency.
While certain exemplary embodiments have been described in detail and shown in the accompanying drawings, it is to be understood that such embodiments are merely illustrative of and not devised without departing from the basic scope thereof, which is determined by the claims that follow.
This Patent application claims priority to U.S. Provisional Patent Application No. 63/202,824 filed on Jun. 25, 2021, entitled “Retrofitting Mechanical Workover Rig to Electro-Mechanical Drive.” The disclosure of the prior application is considered part of and is incorporated by reference into this Patent Application.
Number | Date | Country | |
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63202824 | Jun 2021 | US |