Composite Core Plug for Dynamic Gel Stability Evaluation
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Solution Overview
Problem
Conventional methods for evaluating gelation time and long-term stability of polymer gels used in enhanced oil recovery are inaccurate due to their reliance on static core flooding tests, which do not simulate the dynamic flow conditions encountered in subterranean hydrocarbon formations, and cannot utilize commercially available core plugs and coreholders.
Innovation Solution
A method involving a composite core plug setup in a coreflood testing device, where a first and second core plug are saturated with a polymer solution and a third core plug with a gelent solution, with alternating injections to monitor pressure drop changes, indicating gelation and deterioration, thus maintaining the gel in dynamic flow conditions and allowing for accurate evaluation of gel stability using standard core plugs and holders.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional core flooding tests are used to evaluate gel stability, then the gel remains in static condition during testing, but the test results overestimate gel stability and do not reflect in situ dynamic flow conditions
Solution Approach 1:
The patent applies dynamics by transitioning from static core flooding tests to dynamic alternating flow tests. The core plug is subjected to alternating forward and reverse fluid flows that simulate in situ conditions, where the gel experiences continuous dynamic stress rather than remaining stationary. This dynamic testing approach reveals gel deterioration that static tests miss, improving the reliability of stability evaluations.
Solution Approach 2:
The patent implements periodic action through alternating flow cycles. Fluid is injected alternately in forward and reverse directions through the core plug, creating periodic flow patterns that mimic the fluctuating conditions in actual reservoirs. This periodic dynamic stress accelerates and reveals gel instability, providing more accurate stability assessments compared to continuous static conditions.
2Reliability
If large core plugs with multipoint pressure measurements are used to simulate dynamic flow conditions, then in situ gel stability can be determined, but commercially available core plugs and coreholders cannot be utilized
Solution Approach 1:
The patent applies segmentation by dividing the core plug into three distinct segments: a first core plug segment, a second core plug segment, and a third core plug segment positioned between them. Each segment can be independently saturated with different solutions (polymer solution or gelent solution), allowing dynamic flow testing to be conducted with standard-sized commercially available core plugs while still achieving accurate in situ stability determination.
3Ease of operation
If conventional bottle tests are used to evaluate gel syneresis, then the testing can be conducted at ambient pressure, but the tests are prone to evaporation and do not reflect reservoir conditions
Solution Approach 1:
The patent replaces the simple bottle test mechanical system with a core flooding test system that uses a core holder, pump, and pressure control apparatus. This mechanical substitution allows testing to be conducted under controlled reservoir-like pressures and temperatures, eliminating evaporation issues while maintaining ease of operation through automated fluid injection and pressure monitoring systems.
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 a more accurate assessment of gel stability and longevity by simulating in situ conditions, ensuring the gel remains within the core plug and maintaining dynamic flow, thereby improving the reliability of gel performance predictions.
Implementation Method 1
identifying a gelation of the gelent solution, where the gelation is indicated by an increase in the pressure drop across the composite core plug
Implementation Method 2
a gelent solution comprising at least a polymer and a crosslinker
Data Source
AI summary
A method of evaluating gel stability of a gel for treating a subterranean formation includes placing a composite core plug into a core holder of a coreflood testing device where the composite core plug comprises first, second, and third core plugs, alternating injection of polymer solution into first and second injection areas, and monitoring a pressure drop across the composite core plug as a function of time. The method further includes identifying a gelation of a gelent solution in the third core plug, where the gelation is indicated by an increase in the pressure drop across the composite core plug, after the increase in the pressure drop indicative of the gelation point, continuing alternating injections of the polymer solution into the first and second injection areas, and identifying a reduction in the pressure drop across the composite core plug indicative of deterioration of the gel.