EOS Modeling for Reservoir Fluid Property Determination
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Solution Overview
Problem
Existing methods for drilling oil and gas reservoirs often result in formation damage due to drilling fluid penetration, making it difficult to accurately sample and analyze reservoir fluids, which hampers the determination of unknown properties and the calibration of measurement instruments.
Innovation Solution
The method employs Equation of State (EOS) modeling to determine missing or unknown properties of reservoir fluids by measuring responses of a measuring instrument and physical or chemical properties of the fluid, allowing for the calibration of measurement instruments and the minimization of fluid contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If overbalanced drilling technique is used to maintain well control, then wellbore control is improved, but formation damage occurs due to drilling fluid penetration
Solution Approach 1:
The patent changes the pressure parameter from overbalanced to underbalanced conditions, allowing drilling fluid to flow away from the formation rather than penetrate it, thereby maintaining wellbore control while preventing formation damage
Solution Approach 2:
The patent inverts the conventional drilling approach by using underbalanced drilling instead of overbalanced drilling, reversing the pressure differential to achieve the opposite effect of preventing formation fluid influx while avoiding formation damage
2Reliability
If drilling fluid is circulated to maintain overbalanced condition, then well control is maintained, but skin damage impedes hydrocarbon flow
Solution Approach 1:
The patent changes the pressure parameter from overbalanced to underbalanced conditions, eliminating the pressure differential that causes drilling fluid penetration and skin damage, thereby preserving hydrocarbon flow capacity while maintaining well control
Solution Approach 2:
The patent converts the potential harm of pressure differential into a beneficial flow regime where underbalanced conditions create a natural flow away from the formation, preventing skin damage while maintaining well control through controlled flow
3Loss of information
If fluid sampling is performed after overbalanced drilling, then reservoir fluid analysis is possible, but contamination from drilling fluid reduces measurement precision
Solution Approach 1:
The patent performs preliminary action by using underbalanced drilling from the outset to prevent drilling fluid penetration and contamination before sampling occurs, ensuring that reservoir fluid samples remain uncontaminated and measurement precision is maintained
Solution Approach 2:
The patent applies preliminary anti-action by creating underbalanced conditions that prevent drilling fluid from penetrating the formation before sampling takes place, counteracting the potential contamination effect before it can occur
Data Source
AI summary
The invention relates to a method of determining an unknown property or information of a reservoir fluid. The method includes measuring a set of responses of a measuring instrument to the fluid and measuring one or more physical or chemical properties of the fluid. The method further includes determining the unknown property or information of the fluid based on the relationship between the instrument responses and the measured properties of the fluid using equation-of-state (EOS) model.