Patent Application
20090205869
In drilling a borehole in the earth, such as in exploration and recovery of hydrocarbons, a drill bit is connected on the lower end of an assembly of drill pipe sections connected end-to-end to form a “drill string”. In some cases the drill string and bit are rotated by a drilling table at the surface, and in other cases the drill bit may be rotated by a downhole motor within the drill string above the bit, while remaining portions of the drill string remain stationary. In most cases, the downhole motor is a progressive cavity motor that derives power from drilling fluid (sometimes referred to as “mud”) pumped from the surface, through the drill string, and then through the motor (hence the motor may also be referred to as a “mud motor”).
It is common in the drilling industry to rent downhole equipment, such as mud motors, with the agreement that the billable time will be the total accumulated operating time of the motor. While in most cases the drilling operators correctly report total accumulated operating time, in some cases the operating time is under-reported.
For a detailed description of exemplary embodiments, reference will now be made to the accompanying drawings in which:
Certain terms are used throughout the following description and claims to refer to particular system components. As one skilled in the art will appreciate, drilling equipment companies 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 the following discussion and in the 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.
“Rotary drilling” shall mean that the entire drill string is rotating from the surface.
“Slide drilling” shall mean that only the drill bit and other components in the lower portions of the drill string below the Mud Motor are rotating and the upper portions of the drill string are not rotating.
The following discussion is directed to various embodiments of the invention. Although one or more of these embodiments may be preferred, the embodiments disclosed should not be interpreted, or otherwise used, as limiting the scope of the disclosure, including the claims. In addition, one skilled in the art will understand that the following description has broad application, and the discussion of any embodiment is meant only to be exemplary of that embodiment, and not intended to intimate that the scope of the disclosure, including the claims, is limited to that embodiment.
The various embodiments were developed in the context of a stand-alone, self powered system and method to accumulate rotational time of a downhole progressive cavity motor (mud motor), and will be described in that context; however, the systems and methods find applicability for other rotatable equipment, such as electric motors, and thus the developmental context should not be construed as a limitation as the breadth of the applicability of the systems and methods described herein.
In order to monitor and accumulate the amount of time mud motor 100 is in operation, in some embodiments a sensor 34 is mechanically coupled to a rotatable portion of the mud motor 100. In
In at least some embodiments, the electronic system 36 and sensor 34 are an independent system over which the drilling company renting the mud motor 100 has no control. The electronic system 36 is self-contained, and is capable of monitoring and accumulating rotating usage time based on internally derived power (e.g., from a battery). For example, the electronic system 34 may be operational to accumulate usage time over the course of weeks or months. Once the mud motor 100 is returned by the drilling company to the owner, the owner may access the electronic system 34 and obtain a report of rotational time of the mud motor since leaving possession of the owner. The drilling company's reported usage time may then be compared to the usage time accumulated by the electronic system 36, and appropriate billing action taken.
While it may be possible to have the logic device 42 and sensor 34 continuously active and monitoring for rotation of the mud motor, in order to reduce the power requirements of the battery 44 (and also the size), in some embodiments the sensor 34 and electronic system 36 operate in a low power state. Periodically (e.g., every fifteen minutes), the logic device 42 exits the low power state, activates the sensor 34, makes a determination as to whether the rotor 24 is turning, stores the information, and again enters the low power state. In particular, logic device 42 may couple to battery 44 continuously, but the amount of power drawn during the low power state is small compared to fully operational state of the logic device 42. In yet other embodiments, the logic device 42 may not be coupled to the battery 44, thus drawing no energy from battery 44.
Once the lower power state is exited, the logic device 42 may power the sensor 34 by operation of switch 50, make the determination as to whether the rotor 24 is turning, open switch 50, and re-enter the lower power state. Switch 50 may take many forms. In some embodiments, switch 50 is mechanical or solid state relay. In yet still other embodiments, switch 50 may be transistor (e.g., bipolar junction or field effect) operated as a switch.
Likewise, sensor 34 may take many forms. In some embodiments, sensor 34 is tachometer (e.g., Hall effect type) that measures revolutions of the rotor with respect to the stator (in which case the sensor may be placed on the stator, obviating the need for slip rings). In yet still other embodiments, sensor 34 is an angular rate sensor, for example a solid-state, silicon-based gyroscope. Such a gyroscope is configurable to detect angular rates of the device to which the gyroscope is attached. Thus, when the logic device 42 periodically exits the low power state and powers the sensor 34, the logic device 42 determines rotational state of the rotor 24 based on the angular rate of the rotor 24.
As mentioned above, in some embodiments the electronic system 36 powers the sensor 34 periodically. Consider, for the purpose of explanation, that the sensor 34 is powered a plurality of times (e.g., four times) an hour. If each time the sensor 34 is powered over the course of an hour rotation is sensed by the sensor 34, then the logic device 42 and/or a person who receives the report from the logic device 42, may assume the mud motor 100 was operational over the entire hour. In some embodiments, when the sensor 34 senses rotation, the sensor 34 senses rotation of the rotor 24 relative to the stator 22. In other embodiments, the sensor 34 may sense rotation of the stator 22 relative to the borehole. If rotation is not sensed during one or more times over the illustrative hour, then the logic device 42 and/or the person who receives the report from the logic device, may assume the mud motor 100 was operational less than the entire hour. In particular, the mud motor 100 was operational in proportion to the number of rotating versus non-rotating determinations made.
In addition to the sensor 34 to sense rotation of the rotor 24 of the mud motor 100, some embodiments utilize additional sensors to augment the data regarding rotation. In particular, and still referring to
As yet another example, the additional sensor 60 could be a pressure sensor, which reads parameters such as drilling fluid pressure inside the mud motor, or drilling fluid pressure in the annular space between the drill pipe and the borehole wall. A pressure reading consistent with expected downhole pressure may be used to verify that rotational time accumulated indeed occurred in drilling situations. Yet still another example of an additional sensor 60 is an accelerometer or vibration sensor. High vibration is typically experienced during the drilling process, and thus vibration readings may be used to verify that rotational time accumulated indeed occurred in drilling situations.
In some cases, the owner of the mud motor 100 may wish to charge according to the method of drilling performed by the drilling company. For example, the owner of the mud motor 100 may want to charge a different rate for rotary drilling then for slide drilling.
In some embodiments, sensors 34A-34B are the same, and the sensors 34A-34B sense rotation of a rotatable equipment. In order to protect against temperature, pressure and vibration encountered downhole, the electronic system 36A-36B may reside within a protective casing. In alternative embodiments, the electronic system 36B may be placed in any suitable location on and/or within the mud motor 100. In yet still other embodiments, the sensor 34A and the sensor 34B may couple to a single electronic system 36.
In the particular embodiment, each of the electronic systems 36A-36B powers the corresponding sensor 34A-34B at substantially the same time. If at time the sensors 34A-34B are powered, rotation is sensed by the sensor 34A and the sensor 34B, then the logic device and/or the person who receives the report from the logic device, may assume the mud motor 100 and the drill string coupled to the mud motor 100 were operational. Particularly, the logic device and/or the person who receives the report from the logic device may assume that the drilling company was performing rotary drilling. In the particular embodiment, sensor 34A is configured to sense rotation of the rotor relative to the stator, and sensor 34B is configured to sense the rotation of the stator relative to the borehole. If rotation is sensed by the sensor 34A, and rotation is not sensed by the sensor 34B, then the logic device and/or the person who receives the report from the logic device, may assume the mud motor 100 was operational and the drill string coupled to the mud motor 100 was not operational. Particularly, then the logic device and/or the person who receives the report from the logic device, may assume that the drilling company was performing slide drilling. In alternative embodiments, rotation is sensed by both of the sensors 34A-34B, then the logic device and/or the person who receives the report from the logic device, may assume the mud motor 100 and the drill string coupled to the mud motor 100 were operational.
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. For example, while the electronic system is shown coupled to the stator and the sensor is shown coupled to the rotor, in alternative embodiments the electronics and sensor could be an integrated unit (either on the same semiconductor substrate, or on different substrates yet encapsulated as a single device), and in these embodiments the electronics and sensors may all reside on the rotatable components of the mud motor. It is intended that the following claims be interpreted to embrace all such variations and modifications.
| Number | Date | Country | |
|---|---|---|---|
| 61029000 | Feb 2008 | US |
