Downhole Fluid Property Correction for Pressure Variation
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Solution Overview
Problem
The formation volume factor (FVF) and optical density (OD) measurements of reservoir fluids are inaccurate due to pressure changes downhole, affecting reserve estimation, material balance, and production simulations.
Innovation Solution
A downhole tool is operated to pump fluid from a subterranean formation and obtain series of fluid property measurements, estimating relationships between compressibility and pressure, and correcting OD values based on these measurements to account for pressure variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If FVF and OD measurements are obtained using conventional downhole tools, then fluid properties can be determined for reserve estimation and production simulations, but the measurements become inaccurate due to pressure changes downhole
Solution Approach 1:
The patent applies preliminary action by measuring the initial OD of the reservoir fluid at downhole conditions before significant pressure changes occur. This initial measurement serves as a reference point that is later used to correct subsequent OD measurements taken at different pressures, thereby compensating for the harmful effect of pressure changes on measurement accuracy.
Solution Approach 2:
The patent utilizes parameter changes by establishing a relationship between pressure and OD measurements. By measuring pressure and OD at multiple points and determining how OD varies with pressure, the system can correct OD measurements to account for pressure changes, thus maintaining measurement accuracy despite varying downhole conditions.
2Reliability
If conventional FVF determination methods are used, then reserve estimation and material balance calculations can be performed, but the results are inaccurate because FVF varies with pressure changes that are not accounted for
Solution Approach 1:
The patent implements feedback by continuously monitoring pressure changes downhole and using this information to adjust and correct FVF values. The system establishes a pressure-FVF relationship through measurements and uses this relationship to update FVF estimates in real-time, ensuring that reserve estimation and material balance calculations reflect actual downhole conditions rather than assuming constant FVF.
Solution Approach 2:
The patent applies dynamics by transitioning from a static FVF assumption to a dynamic FVF model that varies with pressure. By measuring OD and pressure at multiple points and determining the functional relationship between them, the system creates a dynamic FVF that adapts to changing downhole conditions, thereby improving the reliability of reservoir simulations and reserve estimates.
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 method provides accurate, real-time correction of OD values and FVF estimates, improving the accuracy of fluid property determinations and simulations by accounting for pressure changes, thereby enhancing reserve estimation and production processes.
Implementation Method 1
FVF and other reservoir fluid properties may be determined utilizing a downhole tool operable to obtain optical density (OD) measurements of the reservoir fluid downhole
Implementation Method 2
A downhole tool is operated within a wellbore adjacent a subterranean formation to pump fluid from the subterranean formation into the downhole tool
Data Source
AI summary
A downhole tool is operated to pump fluid from a subterranean formation while obtaining fluid property measurements pertaining to the pumped fluid. The downhole tool is in communication with surface equipment located at the wellsite surface. The downhole tool and/or surface equipment is operated to estimate a first linear, exponential, logarithmic, and/or other relationship between compressibility and pressure of the pumped fluid based on the fluid property measurements. The downhole tool and/or surface equipment may also be operated to estimate a second linear, exponential, logarithmic, and/or other relationship between formation volume factor and pressure of the pumped fluid based on the first relationship. The downhole tool and/or surface equipment may also be operated to measure and correct optical density of the pumped fluid based on the first relationship.