Wireline Coring DST Tool Packer Sealing and Valve Control
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Solution Overview
Problem
Current drill stem testing (DST) methods face challenges in efficiently sealing and testing borehole zones, particularly when using wireline coring equipment, as they often require complex packer arrangements and may struggle with packer deflation and tool retrieval.
Innovation Solution
A downhole tool is designed to work with wireline coring equipment, featuring packers that can be inflated with liquid to minimize pressure, a dump valve for expeditious deflation, and a main valve that opens and closes without volume change, allowing for precise fluid flow control and pressure measurement during DST, enabling testing in both single and straddle packer configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional packer arrangements are used in wireline coring equipment, then sealing of borehole zones can be achieved, but the system becomes complex and difficult to operate
Solution Approach 1:
The packer system is divided into multiple independently controllable packers (first packer and second packer) that can be inflated and deflated separately through dedicated inflation lines. This segmentation allows each packer to be controlled independently, simplifying the overall operation while maintaining reliable sealing of different borehole zones.
Solution Approach 2:
An intermediary mechanism (latch body and latch fingers) is introduced to automatically latch the tool assembly to the core barrel when packers are inflated. This intermediary component coordinates the sealing function with the retrieval mechanism, reducing operational complexity by automating the latching process rather than requiring separate manual operations.
2Reliability
If packers are inflated to seal borehole zones, then sealing integrity is improved, but pressure requirements increase
Solution Approach 1:
The packers are inflated using hydraulic fluid (inflation fluid) delivered through dedicated inflation lines from the surface. This hydraulic system provides controlled, gradual pressurization that achieves reliable sealing at lower pressures compared to direct mechanical compression, while allowing precise control of inflation levels to match formation pressure conditions.
3Ease of operation
If drill string is raised to open main valve, then fluid flow control is achieved, but volume change occurs affecting pressure measurements
Solution Approach 1:
The traditional mechanical valve operation (requiring drill string rotation or raising) is replaced with a hydraulic actuation system. The main valve is opened and closed by controlling hydraulic pressure to the valve actuator, allowing valve operation without moving the drill string. This substitution eliminates the volume change problem that occurs with mechanical valve operation, thereby maintaining accurate pressure measurements throughout the testing process.
4Stability of the object's composition
If tool is latched to core barrel, then tool stability is improved, but retrieval process becomes complex
Solution Approach 1:
The latching system is designed to be dynamically controllable rather than permanently fixed. Latch fingers can be automatically engaged when packers are inflated and can be automatically disengaged by applying hydraulic pressure to the latch body. This dynamic design allows the tool to be stable during testing operations while simplifying retrieval to a single hydraulic actuation, eliminating complex manual unlatching procedures.
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
This solution enables efficient DST by maintaining seal integrity, minimizing pressure requirements, and allowing for accurate fluid flow and pressure measurement, facilitating both production and injection testing while ensuring tool retrieval and reusability.
Implementation Method 1
packers which can be inflated with liquid to minimize pressure
Implementation Method 2
a dump valve for expeditious deflation
Implementation Method 3
pressure transducers and electronics to record and transmit to the surface information on pressures within the test zone
Data Source
AI summary
Drill stern test apparatus includes a drill string, wireline coring system and a downhole tool that is seated in the core barrel of the coring system. A valve packer within the downhole tool is inflated to seal the core barrel and allow a valve to be operated by movement of the drill string. One or more packers can be inflated to isolate the test zone in the borehole below the coring system. The apparatus is operated to allow the test zone fluid to flow upwardly in the downhole tool and be measured. Downhole tool transducers accumulate the data and transmit the same to the surface. The wireline can be pulled to relieve packer inflation pressure, release a latch and allow the downhole tool to be pulled to the surface while leaving the coring system in place.