Downhole Pressure Sensor Isolation via Elastomeric Sealing
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Solution Overview
Problem
Current pressure measurement techniques in wellbore formations are hindered by sensitivity to borehole fluids, leading to inaccurate inference of formation properties due to noise and area heterogeneity, and existing methods for placing permanent sensors behind casing are cumbersome and prone to errors.
Innovation Solution
A system comprising sensors positioned in direct pressure communication with the formation, isolated from wellbore pressure effects using elastomeric sealing means, which prevents hydraulic pressure communication and allows for accurate pressure measurement data acquisition and interpretation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional borehole logging sonde is used for pressure measurement, then pressure measurement can be made at different depth intervals, but the measurement is sensitive to borehole fluid effects and contains components from both formation and borehole fluid making accurate inference difficult
Solution Approach 1:
The system segments the measurement function by deploying multiple independent pressure sensors at different depth intervals within the wellbore. Each sensor operates independently to measure pressure at its specific location, allowing the system to distinguish between formation pressure and borehole fluid pressure effects through spatial differentiation of the measurements.
Solution Approach 2:
The system transitions from single-point pressure measurement to multi-dimensional pressure monitoring by placing sensors at multiple depth intervals along the wellbore. This spatial distribution across the depth dimension enables differentiation between formation pressure (which varies with depth according to formation properties) and borehole fluid pressure effects (which may be more uniform or follow different patterns).
2Reliability
If permanent sensors are placed outside casing with perforation charges, then sensors can communicate with earth formations, but the operation is difficult and suffers from cable placement issues, cement integrity problems, and potential sensor damage
Solution Approach 1:
The system extracts the sensor placement operation from the complex external process (drilling, cabling, perforation, cementing) and simplifies it by placing sensors directly within the wellbore through the casing. This eliminates the need for external cables and perforation charges, reducing operational complexity while maintaining reliable formation communication through the casing wall.
Solution Approach 2:
The casing itself serves as an intermediary medium that allows sensor placement within the wellbore while maintaining communication with the formation. The sensors positioned inside the wellbore can detect formation pressures transmitted through the casing wall, eliminating the need for direct external sensor placement and perforation operations.
3Measurement precision
If sensors are placed inside cemented casing with sealing, then sensors are insulated from borehole fluids and in direct contact with formation, but leakage affects casing integrity and misinterpretation of pressure measurement
Solution Approach 1:
The system uses pressure transmission through the casing wall as a copy mechanism. Instead of requiring direct sensor contact with formation fluids (which risks leakage), the sensors measure the pressure signal transmitted through the intact casing wall. This creates a reliable indirect measurement that preserves casing integrity while providing accurate formation pressure data.
4Productivity
If sparse measurements of pressure and flow rates are made in limited number of wells, then monitoring can be performed, but the measurements are incomplete and uncertain due to noise and area heterogeneity resulting in incorrect inference of formation properties
Solution Approach 1:
The system segments the monitoring network into multiple distributed sensor locations within each well and across multiple wells. This segmentation of the measurement network provides more comprehensive spatial coverage of the reservoir, reducing the effects of area heterogeneity and providing more complete information for accurate formation property inference while maintaining monitoring efficiency.
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 provides cleaner, reliable pressure measurements, enabling effective reservoir characterization and production forecasting by reducing distortions from wellbore pressure effects and facilitating spatial dynamic measurements for permeability distribution and saturation.
Implementation Method 1
isolating the sensor means with an elastomeric sealing means placed against the formation wall in order to prevent hydraulic pressure communication between the sensor and the interior of the wellbore
Data Source
AI summary
A method of installing a sensor system for making pressure measurements in downhole formations surrounding a wellbore includes placing a sensor in direct pressure communication with the formations from a predetermined position in the wellbore; and isolating the sensor with an elastomeric sealing means placed against the formation wall in order to prevent hydraulic pressure communication between the sensor and the inside of the wellbore.