Polymer Flooding Unit Identification Using Resistivity and Acoustic Logs
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Solution Overview
Problem
Existing polymer flooding methods struggle to identify and develop displaceable units effectively in fully developed oil fields with high heterogeneity and complex injection-production relationships, leading to scattered remaining oil that is challenging to recover.
Innovation Solution
A method and device for determining displaceable units by polymer flooding, involving core sampling, relative permeability experiments, fitting functions, and threshold interval calculations for water saturation, water cut, and deep lateral resistivity parameters, combined with acoustic time difference and resistivity analysis to identify suitable depth positions for polymer flooding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polymer flooding is applied to fully developed oil fields with high heterogeneity, then oil recovery rate can be improved, but it becomes difficult to identify and develop displaceable units effectively due to scattered remaining oil and complex injection-production relationships
Solution Approach 1:
The patent divides the complex oil field into discrete displaceable units by establishing specific identification standards based on water cut intervals, water saturation ranges, and permeability thresholds. This segmentation transforms the scattered remaining oil problem into manageable unit-based development, where each unit can be independently evaluated and targeted for polymer flooding.
Solution Approach 2:
The patent uses parameter changes to identify displaceable units by setting specific thresholds for water cut (e.g., 80-90%, 90-95%), water saturation (e.g., 0.3-0.5, 0.5-0.7), and permeability (e.g., 100-500mD, 500-1000mD). These parameter ranges create clear identification criteria that differentiate displaceable units from non-displaceable areas, enabling effective targeting despite field heterogeneity.
2Measurement precision
If multiple parameters (water saturation, water cut, deep lateral resistivity, acoustic time difference) are used to identify displaceable units, then identification precision is improved, but the complexity of the determination process increases
Solution Approach 1:
The patent segments the identification process into distinct evaluation stages: first evaluating water cut and water saturation parameters, then assessing deep lateral resistivity and acoustic time difference. Each parameter is evaluated against predefined thresholds, and units are classified into different development priorities based on cumulative parameter performance. This segmented approach manages complexity by breaking down multi-parameter analysis into sequential, manageable steps.
Solution Approach 2:
The patent establishes specific parameter threshold ranges to simplify identification: water cut intervals (80-90%, 90-95%), water saturation ranges (0.3-0.5, 0.5-0.7), deep lateral resistivity thresholds, and acoustic time difference criteria. By converting continuous parameter variations into discrete threshold-based classifications, the patent maintains high identification precision while reducing the complexity of the determination process.
3Measurement precision
If core sampling and relative permeability experiments are conducted to obtain fitting functions, then the accuracy of water saturation and water cut parameter determination is improved, but the time and cost of the process increase
Solution Approach 1:
The patent performs core sampling and relative permeability experiments in advance to establish fitting functions that relate water saturation, water cut, and other parameters. These fitting functions are predetermined and stored for rapid application during displaceable unit identification, eliminating the need to conduct experiments for each individual unit assessment. This preliminary action significantly reduces the time required for ongoing parameter determination while maintaining high accuracy.
Data Source
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AI summary
Examples of the present disclosure provide a method and a device for determining a displaceable unit developable by polymer flooding, a medium, and a processor, which belong to the technical field of petroleum development. The method includes: obtaining a plurality of core samples in a working area and relative permeability experiment data of the core samples, and obtaining a fitting function of water saturation parameters and water cut parameters in the working area according to the relative permeability experiment data; calculating a corresponding water saturation parameter threshold interval according to the fitting function and a preset water cut parameter threshold interval, and calculating a deep lateral resistivity parameter threshold interval corresponding to the water saturation parameter; and obtaining acoustic time difference parameter curves and deep lateral resistivity parameter curves at different depth positions, and determining the displaceable unit developable by polymer flooding according to whether a deep lateral resistivity parameter and an acoustic time difference parameter simultaneously fall into corresponding parameter threshold intervals at each depth position. According to the method for determining a displaceable unit developable by polymer flooding in the present application, the displaceable unit developable by polymer flooding can be found from a developed reservoir.