Wellbore Pump-Down Control for Tension and Stick-Slip Stability
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Solution Overview
Problem
Manual control of downhole tool strings in wellbore operations is inefficient due to difficulties in preventing and managing 'pump-off' and 'stick-slip' events, which occur when excessive fluid pressure causes tension issues and frictional drag, respectively, leading to suboptimal conveyance and potential equipment disconnection or slowed progress.
Innovation Solution
An automated control system that monitors and adjusts the conveyance device and fluid pump operations in real-time, using sensors to maintain optimal tension and flow rates, preventing excessive tension and friction by coordinating the conveyance line unwinding and fluid injection to ensure consistent speed and tension along the wellbore.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If manual control is used to monitor and control wellsite equipment, then operational flexibility is maintained, but undesirable operational events such as pump-off and stick-slip events are difficult to prevent and control
Solution Approach 1:
The control system continuously monitors operational parameters (depth, speed, fluid pressure, flow rate) and uses this feedback to automatically adjust pump operations and conveyance device operations, preventing pump-off and stick-slip events before they occur
Solution Approach 2:
The system performs self-regulation by automatically detecting operational conditions and adjusting its own parameters without human intervention, with the control system managing both conveyance device and fluid pump operations based on real-time sensor data
2Speed
If fluid pressure is increased to push the tool string faster, then conveyance speed increases, but excessive tension is caused leading to cable head disconnection
Solution Approach 1:
The control system monitors tension forces and fluid pressure in real-time, automatically reducing fluid pressure when tension approaches dangerous levels, thereby maintaining safe operating conditions while maximizing conveyance speed
Solution Approach 2:
The system dynamically adjusts operational parameters (fluid pressure, flow rate, conveyance device speed) based on real-time conditions, changing them continuously to maintain optimal speed while preventing excessive tension
3Reliability
If fluid flow rate is increased to reduce frictional drag, then stick-slip events are reduced, but excessive fluid pressure is generated causing tension issues
Solution Approach 1:
The control system simultaneously monitors both fluid pressure and tool string movement, adjusting flow rate dynamically to maintain sufficient fluid movement for preventing stick-slip while keeping pressure within safe limits
Solution Approach 2:
The system employs dynamic control where operational parameters are continuously adjusted based on real-time conditions rather than using fixed settings, allowing optimal prevention of stick-slip events without generating excessive pressure
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The automated system significantly reduces the occurrence of pump-off and stick-slip events, allowing for smoother and more efficient conveyance of tool strings along the wellbore, enhancing operational reliability and productivity by maintaining consistent speed and tension.
Implementation Method 1
a fluid pump operable to pump a fluid into the wellbore such that the fluid moves the tool string along the wellbore
Implementation Method 2
a conveyance device operable to unwind the conveyance line at a rate that varies to vary a tension that the conveyance line applies to the tool string
Data Source
AI summary
An apparatus and method for performing automated pump-down operations. An apparatus may include a control system configured to be communicatively connected with a fluid pump disposed at a wellsite surface and with a conveyance device disposed at the wellsite surface. The control system may be operable to cause the conveyance device to unwind a conveyance line connected with a tool string disposed within a wellbore, and cause the fluid pump to pump a fluid into the wellbore such that the fluid moves the tool string along the wellbore while the conveyance device unwinds the conveyance line.