Multi-Probe Formation Testing Tool Gradient Determination
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Solution Overview
Problem
Accurately determining formation pressure gradients in boreholes is operationally difficult due to the need for multiple position measurements and precise depth determination, which affects the quality and efficiency of formation pressure measurements.
Innovation Solution
A system using a formation testing tool with two or more probes positioned at determined depths based on pre-measured well logs and quality factors, allowing for simultaneous pressure measurements without moving the tool, and calculating the pressure gradient from the known distance between probes, thereby reducing operational complexity and improving measurement accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple position measurements are performed by moving the formation testing tool to different depths, then the formation pressure gradient can be determined, but the operational complexity and time consumption increase
Solution Approach 1:
The formation testing tool is divided into multiple probes (first probe and second probe) positioned at different depths within the same tool body. This segmentation allows simultaneous pressure measurements at multiple depths without moving the entire tool, thereby reducing time loss while maintaining measurement precision for gradient calculation.
Solution Approach 2:
The invention transitions from a single-depth measurement approach to a multi-depth simultaneous measurement approach by incorporating multiple probes at different vertical positions within the tool. This dimensional change in measurement capability allows gradient determination from a single tool position, eliminating the need to move the tool between depths.
2Measurement precision
If the formation testing tool is moved to various test points to perform pressure measurements, then the formation pressure gradient can be calculated, but the operational difficulty increases due to the need for precise depth determination
Solution Approach 1:
The tool is segmented into multiple probes with fixed known spacing. Each probe independently measures pressure at its specific depth, eliminating the need to precisely determine the tool's overall position. The known probe spacing simplifies operations while maintaining gradient calculation accuracy through simultaneous multi-depth measurements.
3Reliability
If considerable time is spent moving the formation pressure tool to different positions to find suitable test positions, then measurement quality improves, but productivity decreases
Solution Approach 1:
Multiple probes are segmented throughout the tool body, each capable of independent pressure measurement. This allows the system to evaluate measurement quality at multiple depths simultaneously without moving the tool, improving reliability through multi-point assessment while maintaining high productivity by eliminating repetitive positioning operations.
Solution Approach 2:
The multiple probes enable continuous useful action by performing pressure measurements at multiple depths simultaneously in a single tool position. This eliminates the intermittent process of moving the tool between positions, thereby maintaining continuous data acquisition and improving both measurement reliability and operational productivity.
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 approach enables accurate and efficient determination of formation pressure gradients, reducing the need for multiple position measurements and improving the quality of pressure data, which aids in fluid zone delineation and oil reserve estimation.
Implementation Method 1
a small amount of fluid is drawn from the geologic formation through the probe and into the formation testing tool producing a pressure disturbance. If the draw is sufficient to cause pressure in the probe to decrease below the formation pressure, then generally when the draw stops the pressure builds back up. A stable build-up of the pressure indicates the formation pressure.
Data Source
AI summary
Quality factors associated with formation pressure measurements at various depths in the geologic formation are determined based on one or more well logs of formation properties in a geologic formation. A formation testing tool with two or more probes is positioned in a borehole of the geologic formation based on the quality factors. The two or more probes in the borehole perform respective formation pressure measurements, where each formation pressure measurement is performed at a different depth. The formation pressure measurements and the given distance between the two or more probes indicate a formation pressure gradient.