US-12618319-B1 - Methods and systems for detecting and mitigating downhole motor dysfunction

US12618319B1US 12618319 B1US12618319 B1US 12618319B1US-12618319-B1

Abstract

Methods and systems are provided for detecting and mitigating stall of a downhole motor driven by flow of drilling fluid through the downhole motor, which employ a BHA that includes at least one first downhole sensor and at least one second downhole sensor operably disposed above the downhole motor. The methods and systems generate time-series first data representing measurements of the rotational speed of a collar disposed at the uphole end of the downhole motor or part of the BHA disposed above the downhole motor made by the at least one first downhole sensor over time as well as time-series second data representing measurements of the vibration of the BHA made by the at least one second downhole sensor over time. Stall of the downhole motor can be automatically detected by analysis of the time-series first data and the time-series second data. Upon detecting stall of the downhole motor, at least one action can be initiated to mitigate the stall of the downhole motor.

Inventors

Ashley Bernard Johnson

Assignees

SCHLUMBERGER TECHNOLOGY CORPORATION

Dates

Publication Date: 20260505
Application Date: 20250311

Claims (19)

1 . A method for detecting and mitigating stall of a downhole motor driven by flow of drilling fluid through the downhole motor, the method comprising: providing a bottomhole assembly (BHA) that includes at least one first downhole sensor and at least one second downhole sensor which are both operably disposed above the downhole motor; configuring the at least one first downhole sensor to measure rotational speed of a collar, wherein the collar is disposed at an uphole end of the downhole motor or is part of the BHA disposed above the downhole motor; configuring the at least one second downhole sensor to measure vibration of the BHA; generating time-series first data representing measurements of the rotational speed of the collar made by the at least one first downhole sensor over time; generating time-series second data representing measurements of the vibration of the BHA made by the at least one second downhole sensor over time; automatically detecting stall of the downhole motor by analysis of the time-series first data and the time-series second data, wherein the analysis of the time-series first data and the time-series second data comprises i) evaluating rotational speed of the collar using one or more conditions corresponding to stall of the downhole motor, and ii) evaluating vibration of the BHA using one or more conditions that detect a synchronous drop in the time-series second data that corresponds to stall of the downhole motor; and upon detecting stall of the downhole motor, initiating at least one action to mitigate the stall of the downhole motor.
2 . The method of claim 1 , wherein: the analysis of the time-series first data and the time-series second data is configured to automatically detect stall of the downhole motor if and when the time-series first data corresponds to, or indicates, a stationary collar at or near null rotational speed and the time-series second data corresponds to, or indicates, a drop in vibration synchronous to the stationary collar at or near null rotational speed.
3 . The method of claim 1 , wherein: the analysis of the time-series first data and the time-series second data is configured to automatically detect stall of the downhole motor if and when the time-series first data corresponds to, or indicates, a drop in rotational speed of the collar and the time-series second data corresponds to, or indicates, a drop in vibration synchronous to the drop in rotational speed of the collar.
4 . The method of claim 1 , wherein the analysis of the time-series first data and the time-series second data involves: computing a characteristic rotational speed of the collar which is evaluated in i) using one or more conditions corresponding to stall of the downhole motor; and computing a characteristic vibration level of the BHA, which is evaluated in ii) using the one or more conditions that detect a synchronous drop in the time-series second data that corresponds to stall of the downhole motor.
5 . The method of claim 1 , wherein: the at least one action involves alerting a drilling operator to the stall of the downhole motor.
6 . The method of claim 5 , wherein: the alerting comprises communication or display of a message or indicator of the stall of the downhole motor.
7 . The method of claim 5 , wherein: the at least one action further involves the drilling operator adjusting flow rate of the drilling fluid flowing through the downhole motor or adjusting motor speed of the downhole motor.
8 . The method of claim 1 , wherein: the at least one action involves issuing and communicating at least one control command that automatically adjusts flow rate of the drilling fluid flowing through the downhole motor or automatically adjusts motor speed of the downhole motor.
9 . The method of claim 8 , wherein: the at least one control command is issued by a control system or processor.
10 . The method of claim 1 , wherein: the stall of the downhole motor comprises a micro motor stall event or a full motor stall event.
11 . A directional drilling system comprising: a bottomhole assembly (BHA) that includes a drill bit, a downhole motor, and at least one first downhole sensor and at least one second downhole sensor which are both operably disposed above the downhole motor, wherein the downhole motor is driven by flow of drilling fluid through the downhole motor, wherein the at least one first downhole sensor is configured to measure rotational speed of a collar, wherein the collar is disposed at an uphole end of the downhole motor or is part of the BHA disposed above the downhole motor, and wherein the at least one second downhole sensor is configured to measure vibration of the BHA; and at least one processor configured to: i) generate time-series first data representing measurements of the rotational speed of the collar made by the at least one first downhole sensor over time; ii) ii) generate time-series second data representing measurements of the vibration of the BHA made by the at least one second downhole sensor over time; iii) iii) automatically detect stall of the downhole motor by analysis of the time-series first data and the time-series second data, wherein the analysis of the time-series first data and the time-series second data comprises i) evaluating rotational speed of the collar using one or more conditions corresponding to stall of the downhole motor, and ii) evaluating vibration of the BHA using one or more conditions that detect a synchronous drop in the time-series second data that corresponds to stall of the downhole motor; and iv) iv) upon detecting stall of the downhole motor, initiate at least one action to mitigate the stall of the downhole motor.
12 . The directional drilling system of claim 11 , wherein: the analysis of the time-series first data and the time-series second data is configured to automatically detect stall of the downhole motor if and when the time-series first data corresponds to, or indicates, a stationary collar at or near null rotational speed and the time-series second data corresponds to, or indicates, a drop in vibration synchronous to the stationary collar at or near null rotational speed.
13 . The directional drilling system of claim 11 , wherein: the analysis of the time-series first data and the time-series second data is configured to automatically detect stall of the downhole motor if and when the time-series first data corresponds to, or indicates, a drop in rotational speed of the collar and the time-series second data corresponds to, or indicates, a drop in vibration synchronous to the drop in rotational speed of the collar.
14 . The directional drilling system of claim 11 , wherein the analysis of the time-series first data and the time-series second data involves: computing a characteristic rotational speed of the collar using one or more conditions corresponding to stall of the downhole motor; and computing a characteristic vibration level of the BHA, which is evaluated in ii) using the one or more conditions that detect a synchronous drop in the time-series second data that corresponds to stall of the downhole motor.
15 . The directional drilling system of claim 11 , wherein: the at least one action involves alerting a drilling operator to the stall of the downhole motor.
16 . The directional drilling system of claim 15 , wherein: the alerting comprises communication or display of a message or indicator of the stall of the downhole motor.
17 . The directional drilling system of claim 15 , wherein: the at least one action further involves the drilling operator adjusting flow rate of the drilling fluid flowing through the downhole motor or adjusting motor speed of the downhole motor.
18 . The directional drilling system of claim 11 , wherein: the at least one action involves issuing and communicating at least one control command that automatically adjusts flow rate of the drilling fluid flowing through the downhole motor or automatically adjusts motor speed of the downhole motor.
19 . The directional drilling system of claim 11 , wherein: the stall of the downhole motor comprises a micro motor stall event or a full motor stall event.

Description

BACKGROUND This section provides background information to facilitate a better understanding of the various aspects of the disclosure. It should be understood that the statements in this section of this document are to be read in this light, and not as admissions of prior art. Oil and gas reservoirs may be accessed by drilling wellbores to enable the production of hydrocarbon fluid, e.g., oil and/or gas, to a surface location. Geothermal reservoirs may be accessed by drilling wellbores to enable the production of geothermal fluid, e.g., steam or hot working fluid, to a surface location. In many environments, directional drilling systems are used to gain better access to the desired reservoirs by forming deviated wellbores as opposed to traditional vertical wellbores. A directional drilling system typically employ a rotary steerable system (RSS) that enables control over the drilling direction. The RSS can often be classified as a push-the-bit system or a point-the-bit system. The RSS allow an operator to change the orientation of the drill bit while drilling and thus the direction of the wellbore while drilling. Directional drilling systems also typically employ a mud motor that drives rotation of the RSS and the drill bit. The mud motor is a progressive cavity positive displacement (PCPD) pump that uses drilling fluid to create rotary motion of a rotor in the motor's power section. The rotary motion of the rotor is transmitted to the RSS and the drill bit. Mud motors are prone to operational and environmental damage, with fatigue in the power section ultimately leading to failure. Typically, an elastomer forms a rubber lining between the walls of the rotor and stator of the mud motor. As directional drilling systems are used to drill deeper and longer lateral wellbores in hotter environments, elastomer failure remains a significant bottleneck in drilling performance. Mud motor failure can contribute to excessive non-productive time associated with tripping the mud motor out and possibly replacing it altogether, causing operators to fall behind operational targets. In addition to failure, mud motor damage can also compromise drilling efficiency even in cases where the target depth of the wellbore is successfully reached. These deficiencies create significant cost increases for directional drilling operations and are a critical problem to be solved. Motor stalls (also referred to as “full motor stalls” herein) are known to be a significant contributor to damage of the elastomer of a mud motor during drilling. A motor stall occurs when the mud motor generates insufficient torque to overcome the power demand created by excessive weight on bit or sudden changes in formation, causing the bit to stop rotating. The buildup and eventual release of excessive torsional and frictional forces can cause significant damage to the power section of the mud motor. With continued circulation, the drilling fluid can force its way between the rotor and elastomer, eventually leading to chunking and erosion. Motor stalls typically occur without warning and last for a small duration of time, usually tens of seconds or more. Generally this requires intervention from the rig. Micro motor stall is a precursor to full motor stall and lasts only for a very short duration of time typically less than 10 seconds and the motor will restart without intervention. Micro motor stall can be a driver for accelerated wear and pressure pulsations which can damage other tools. As such, micro motor stall is an indicator of potential wear and tool damage. Effectively detecting and mitigating micro motor stall can bring benefits in performance and reliability of the directional drilling system. SUMMARY 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 claimed subject matter. In some embodiments, the techniques described herein relate to a method for detecting and mitigating stall of a downhole motor. A bottomhole assembly (BHA) can be provided that includes a downhole motor driven by flow of drilling fluid through the downhole motor, and at least one first downhole sensor and at least one second downhole sensor which are both operably disposed above the downhole motor. The at least one first downhole sensor can be configured to measure rotational speed of a collar that is disposed on the uphole end of the downhole motor or that is part of the BHA disposed above the downhole motor. The at least one second downhole sensor can be configured to measure vibration of the BHA. Time-series first data representing measurements of the rotational speed of the collar made by the at least one first downhole sensor over time can be generated and stored. Time-series second data representing measurements of the vibration of the BHA m