Formation Tester Seal Integrity Detection via Pressure Phase Comparison
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Solution Overview
Problem
Existing formation testing technologies face challenges in accurately determining the integrity of the seal between a formation tester and the formation, which is crucial for obtaining representative formation fluid samples and preventing contamination from borehole fluids.
Innovation Solution
The proposed solution involves determining the effectiveness of the seal by comparing pressure measurements across different phases of a formation measurement operation, such as the probe setting, drawdown, and buildup phases, using statistical parameters like standard deviation to assess seal integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a seal is formed between the formation tester and the formation wall, then the reliability of formation fluid sampling is improved, but the difficulty of detecting and measuring seal integrity increases
Solution Approach 1:
The patent introduces an intermediary substance (fluid) between the formation tester and the formation wall to create a detectable pressure system. By injecting fluid into the seal cavity and monitoring pressure changes, the system mediates the detection of seal integrity without requiring direct observation of the seal itself, thus resolving the contradiction between ensuring seal reliability and detecting its integrity.
Solution Approach 2:
The patent implements a feedback mechanism where pressure sensors continuously monitor the pressure within the seal cavity during formation testing. The system compares measured pressure values against expected pressure ranges and provides feedback to determine whether the seal is intact or has failed, enabling real-time detection and measurement of seal integrity.
2Productivity
If pressure testing is performed to evaluate formation properties, then the productivity of formation evaluation is improved, but the risk of contamination from borehole fluids increases
Solution Approach 1:
The patent divides the testing system into separate isolated zones using the seal mechanism. The seal creates distinct compartments: one containing formation fluids and another containing borehole fluids, preventing contamination while allowing independent pressure testing of the formation zone, thus enabling efficient evaluation without mixing of fluid types.
Solution Approach 2:
The patent uses an intermediary seal mechanism and isolated cavity system to prevent direct contact between formation fluids and borehole fluids. The seal acts as a barrier that mediates between the two fluid systems, allowing pressure transmission for testing while maintaining fluid separation and preventing contamination.
Data Source
AI summary
Systems and techniques are provided for determining an integrity of a seal between a formation tester and a formation during formation testing. An example method can include controlling placement of a probe of a formation tester from a wellbore and into a formation as part of a formation measurement operation performed by the formation tester in the formation; gathering first pressure measurements through a probe during a probe setting phase of the formation measurement operation; gathering second pressure measurements through the probe during a phase of the formation measurement operation after the probe setting phase; and determining an integrity of a seal between a packer of the formation tester and the formation based on a comparison of the first pressure measurements gathered during the probe setting phase and the second pressure measurements gathered during the phase of the formation measurement operation after the probe setting phase.