Reservoir Simulator Well Pressure Calculation via Flux-Based Drainage Volume
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Solution Overview
Problem
Conventional reservoir simulators face inaccuracies in computing static well pressures, especially for complex well shapes, leading to inefficient use of computer resources and introduction of unrealistic permeability modifiers during history matching.
Innovation Solution
The method computes approximate static well pressures using drainage volume averaged grid block pressures within the drainage volume of arbitrary shaped wells, calculated from flux maps of reservoir fluid flux vectors, eliminating the need for pressure build-up tests and correction factors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pore volume averaged grid block pressures are used to approximate static well pressure, then the approximation is reasonable for very large grid blocks, but the error becomes significant for smaller grid blocks when locally refined grids around the well are used
Solution Approach 1:
The patent changes the parameter used for pressure approximation from pore volume averaged grid block pressure to drainage volume averaged pressure. This parameter change allows accurate static well pressure calculation even with locally refined grids, as the drainage volume is specifically defined to represent the actual drainage area of the well, making the approximation accurate regardless of grid block size.
2Adaptability or versatility
If correction factors are applied to correct static pressure estimated using pore volume averaged grid block pressures, then the correction works for vertical wells, but the correction factors fail to function appropriately for multi-lateral wells and wells with complex shapes
Solution Approach 1:
The patent creates a universal method for calculating static well pressure that works for all well types including vertical wells, multi-lateral wells, and wells with complex shapes. The drainage volume is defined based on flux vectors, which naturally adapt to any well geometry, making the method universally applicable without requiring different correction factors for different well types.
Solution Approach 2:
The patent changes from using correction factors (which are geometry-specific) to using drainage volume averaged pressure (which is geometry-adaptive). The drainage volume is calculated based on actual flux patterns, which automatically adjust to any well shape, providing both universality and accuracy.
3Loss of time
If interpolation techniques are used to accommodate the difference in build-up test times and simulator time steps, then the time domain mismatch is addressed, but the technique results in an inefficient use of computer processing resources and may require wrongfully introducing permeability modifiers
Solution Approach 1:
The patent makes the simulator compute static well pressure directly at every time step through drainage volume averaged pressure calculation, eliminating the need for separate build-up test simulations and interpolation procedures. This self-service approach computes the required pressure values directly during the simulation, avoiding additional processing steps and the need for permeability modifiers.
4Quantity of substance
If the reservoir simulator calculates a static well pressure at each simulated time step, then comprehensive pressure data is generated, but the number of simulated static well pressures vastly outnumbers the number of actual build-up tests
Solution Approach 1:
The patent extracts only the relevant pressure information (drainage volume averaged pressure) that corresponds to what would be measured in actual build-up tests. By computing this specific metric directly at each time step, the simulator generates pressure data that is both comprehensive in coverage and directly comparable to field measurements, eliminating the need for time-consuming interpolation and matching procedures.
Data Source
AI summary
Systems, computer implemented methods, and program products to determine approximate static well pressures for one or more arbitrary shaped wells by estimating the drainage volume of the one or more wells, are provided. The drainage volume of the one or more wells, for example, can be estimated from the one or more computed fluid flow flux vectors, and the approximate static well pressures for the one or more wells can be subsequently calculated by taking the pore volume average of the dynamic grid block pressures within the drainage volume of the one or more wells. The one or more fluid flow flux vectors can be calculated at each iteration in a numerical reservoir simulator as a part of standard simulator computations, negating a need for additional, extraneous computations to calculate effective drainage volume of the one or more wells.