Modified Flotation Test for In-Situ Reservoir Wettability
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Solution Overview
Problem
Current wettability testing methods for oil reservoirs fail to accurately measure and predict in-situ wettability due to the lack of control over pH conditions, which is crucial for understanding and modifying wettability to enhance oil recovery, as they do not replicate the in-situ pH of the reservoir.
Innovation Solution
A modified flotation test method that controls the experimental pH of the test vessel to match the in-situ pH of the oil reservoir by adjusting the gas/liquid phase chemistry, including the partial pressure of CO2, to accurately measure wettability and determine equilibrium constants for geochemical models, allowing for the design of injected water to optimize oil recovery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional wettability testing methods are used without controlling pH conditions, then the testing procedure is simple and quick, but the measurement precision of in-situ wettability is poor
Solution Approach 1:
The patent applies parameter changes by controlling the pH of the aqueous phase in the flotation test to match the in-situ reservoir pH conditions. This involves adjusting chemical parameters (pH, ionic strength, gas composition) to replicate reservoir environment, thereby improving wettability measurement accuracy while maintaining a relatively simple flotation test framework
2Measurement precision
If in-situ reservoir conditions are replicated in the flotation test, then the wettability measurement accuracy improves, but the device complexity and operational complexity increase
Solution Approach 1:
The patent applies preliminary action by pre-calculating and preparing the aqueous phase composition to match in-situ reservoir conditions before conducting the flotation test. The pH and chemical composition are adjusted in advance based on known reservoir parameters, so that when the test is performed, the conditions are already optimized for accurate measurement without requiring complex real-time adjustments during operation
3Reliability
If the aqueous phase chemistry is controlled to match in-situ conditions, then the reliability of wettability predictions improves, but the time required for test preparation and execution increases
Solution Approach 1:
The patent applies preliminary action by pre-determining the aqueous phase composition based on reservoir data before the flotation test. The pH, ionic strength, and gas composition are calculated and prepared in advance, allowing the actual test to proceed quickly under pre-optimized conditions that ensure reliable wettability predictions
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 more accurate wettability measurements and predictions, enabling the modification of wettability for improved oil recovery by ensuring that the experimental conditions closely resemble the in-situ conditions of the oil reservoir, thereby optimizing the interaction between injected water and the reservoir rock and oil.
Implementation Method 1
controlling a chemistry of the gas/liquid phase sample to achieve an experimental pH value in the test vessel corresponding to conditions of the oil reservoir of interest
Implementation Method 2
Wettability describes the preference of a solid surface to be in contact with one fluid rather than another fluid. This preference is based on atomic-scale surface and interfacial forces
Data Source
AI summary
Measurement of in-situ petroleum reservoir wettability at the current salinity and at different salinities and water compositions. That data may be used to derive the crude oil acid and base equilibrium constants for the oil-surface adhesion reaction that control wettability. These constants may be used in quantitative models of the reservoir wettability. This procedure produces an accurate description of reservoir wettability and identifies the specific water chemistry that will optimize in-situ wettability and, in turn, oil production.