Downhole Saturation Pressure Correction for OBM Filtrate Contamination
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Solution Overview
Problem
Oil-based mud filtrate contamination affects the accuracy of downhole fluid properties measurements, making it difficult to determine the saturation pressure of uncontaminated fluids, which is crucial for reservoir development and production.
Innovation Solution
A method and system that use downhole tools to measure and correct for oil-based mud filtrate contamination by determining a relationship between saturation pressure measurements and filtrate contamination, allowing for the extrapolation of saturation pressure to zero contamination levels, enabling the determination of uncontaminated fluid saturation pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If downhole fluid samples are obtained during drilling operations, then fluid property measurements can be performed, but the samples become contaminated with oil-based mud filtrate reducing measurement accuracy
Solution Approach 1:
The patent applies preliminary action by performing contamination correction calculations before final saturation pressure determination. The system first measures saturation pressure at multiple known contamination levels, then extrapolates to zero contamination to obtain the corrected saturation pressure value, preventing contamination from affecting the final measurement result
Solution Approach 2:
The patent converts the harmful effect of OBM filtrate contamination into a beneficial measurement approach. By intentionally allowing contamination and measuring saturation pressure at multiple known contamination levels, the system can use the contamination itself as a variable to extrapolate and determine the true saturation pressure of uncontaminated fluid, turning the harmful contamination into a useful measurement parameter
2Measurement precision
If multiple saturation pressure measurements are taken at different contamination levels, then contamination correction can be achieved, but measurement time and operational complexity increase
Solution Approach 1:
The patent applies parameter changes by varying the contamination level parameter across multiple measurements. By measuring saturation pressure at different known contamination levels (0%, 10%, 20%, etc.), the system creates a data set that can be extrapolated to determine the saturation pressure at zero contamination, achieving high precision through systematic parameter variation
Solution Approach 2:
The patent uses feedback by continuously monitoring and measuring the actual contamination level of each fluid sample, then using this feedback information to select appropriate correction factors and extrapolation methods. The system adjusts its correction approach based on the measured contamination level, improving accuracy while optimizing measurement time
Data Source
AI summary
Embodiments of the disclosure can include systems, methods, and devices for determining saturation pressure of an uncontaminated fluid. Downhole saturation pressure measurements and downhole OBM filtrate contamination of a contaminated fluid may be obtained and a relationship may be determined between the saturation pressure measurements and OBM filtrate contamination. The relationship may be extrapolated to zero OBM filtrate contamination to determine the saturation pressure of the uncontaminated fluid. In some embodiments, OBM filtrate contamination may be determined from downhole saturation pressure measurements during pumpout of a fluid.