Joint Inversion of Time-Lapse EM and Flow Data for Reservoir Characterization
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Solution Overview
Problem
Current methods for estimating relative permeability and capillary pressure in hydrocarbon reservoirs are limited, relying on flow simulation modeling and are ineffective at distances away from boreholes, necessitating improved estimation for optimized production.
Innovation Solution
A method combining time-lapse electromagnetic and flow data through joint inversion, using parametric and dual-permeability-porosity modeling to determine these parameters over large reservoir sections, even with data from only a few wells, by modeling steel well casings and adjusting numerical meshes for efficient computation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If flow simulation modeling is used to estimate relative permeability and capillary pressure, then estimation can be performed, but the estimation is ineffective at distances away from boreholes where core data is available
Solution Approach 1:
The patent introduces electromagnetic data as an intermediary that bridges the gap between borehole measurements and reservoir-wide characterization. The electromagnetic method provides independent information about fluid saturation and distribution in the reservoir, which serves as a mediator to constrain the flow simulation and extend accurate estimation beyond the immediate borehole vicinity.
Solution Approach 2:
The patent merges electromagnetic data with flow simulation data in a joint inversion framework. By combining these two independent data sources, the method achieves accurate estimation of relative permeability and capillary pressure functions across the entire reservoir volume, not just near boreholes. The electromagnetic data provides spatial coverage while the flow data provides physical constraints.
2Measurement precision
If joint inversion of electromagnetic and flow data is performed, then accurate estimation over large reservoir areas is achieved, but computational complexity increases
Solution Approach 1:
The patent performs preliminary processing of electromagnetic data to extract fluid saturation information before the joint inversion. This preliminary action prepares the electromagnetic data in a form that is directly compatible with the flow simulation constraints, reducing the computational burden during the actual joint inversion process.
Solution Approach 2:
The patent transforms the joint inversion problem by changing parameters from direct estimation of relative permeability and capillary pressure functions to estimation of fluid saturation distribution from electromagnetic data, which then constrains the flow simulation. This parameter transformation simplifies the computational problem while maintaining accuracy.
Data Source
AI summary
A method is described for subsurface hydrocarbon reservoir characterization including receiving a time-lapse electromagnetic (EM) dataset and a flow dataset; inverting the time-lapse EM dataset using a parametric inversion that models steel well casings to determine a volume of fluid-changed reservoir; inverting the time-lapse EM dataset and the flow dataset using a joint inversion that honors the volume of the fluid-changed reservoir to determine relative permeability and capillary pressure; and characterizing flow characteristics in the volume of the fluid-changed reservoir. The method may be executed by a computer system.