Composite Core Plug Gelation Time Determination
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Solution Overview
Problem
Conventional methods for determining gelation time in core plugs are inaccurate and cannot be conducted at in situ conditions due to the large size of core plugs and the lack of commercially available coreholding setups that can handle them.
Innovation Solution
A method involving a composite core plug setup where two smaller core plugs are coupled to a central core plug, saturated with polymer and gel solutions respectively, and monitored for pressure changes during alternating polymer solution injections to determine gelation time using a commercially available coreholder.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional bottle test is used for gelation time determination, then the test can be conducted with simple equipment, but the measurement accuracy is poor and evaporation occurs during testing
Solution Approach 1:
The patent introduces a core plug as an intermediary medium between the gel solution and the core holder. The core plug provides a controlled porous environment that prevents evaporation while allowing gelation to occur, thereby improving measurement accuracy without requiring complex specialized equipment. The core plug acts as a mediator that creates in situ-like conditions within a commercially available core holder.
2Measurement precision
If large core plugs are used to determine in situ gelation time, then the measurement accuracy improves, but specialized coreholding setups are required which are not commercially available
Solution Approach 1:
The patent segments the core plug into a standard size that fits commercially available core holders, eliminating the need for specialized equipment. By using a appropriately sized core plug (e.g., 1-inch diameter) rather than large core samples, the invention maintains measurement accuracy while using off-the-shelf core holding equipment, thus reducing device complexity.
3Ease of manufacture
If conventional coreholding setups are used, then the equipment is commercially available, but they cannot accommodate large core plugs needed for in situ gelation time determination
Solution Approach 1:
The patent changes the size parameter of the core plug to match the capacity of commercially available core holders. Instead of using large core plugs that require specialized equipment, the invention uses standard-sized core plugs (e.g., 1-inch diameter, 1-2 inches length) that fit existing equipment while still providing sufficient volume for accurate gelation time measurement under in situ conditions.
4Ease of operation
If polymer solution is continuously injected into a single area, then the injection process is simple, but viscous fingering occurs which affects measurement accuracy
Solution Approach 1:
The patent implements periodic action by alternating the injection area between two different locations in the core plug. Instead of continuous injection at a single point, the injection is periodically switched between two areas, which prevents viscous fingering by distributing the polymer solution more uniformly through the core plug pores, thereby improving measurement accuracy while maintaining operational simplicity.
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
Enables accurate determination of gelation time at in situ conditions without the need for specialized equipment, simulating the actual formation conditions and reducing evaporation and viscous fingering issues.
Implementation Method 1
monitoring the pressure drop, or pressure profile change, across the composite core plug during the alternating injection of polymer solution to determine the gelation time
Implementation Method 2
The second and third core plugs are saturated with polymer solution
Data Source
AI summary
A method of determining gelation time is disclosed that includes placing a composite core plug into a core holder of a commercially-available vessel. The composite core plug includes a first core plug with second and third core plugs disposed on opposite sides of the first core plug. The second and third core plugs are saturated with polymer solution, and the first core plug is saturated with gel solution comprising polymer and crosslinker. The method further includes alternating polymer solution injections between a first injection area located on the second core plug and a second injection area located on the third core plug, while ensuring that the polymer solution is being continuously fed to the composite core plug. The pressure drop across the composite core plug is monitored during the alternating injection of polymer solution to determine the gelation time of the gel solution in the first core plug.