Temperature-Responsive Self-Degradable Temporary Plugging Agent
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Solution Overview
Problem
Existing liquid gel plugs used in oil and gas well operations face challenges with increased viscosity, making them difficult to pump and degrade, requiring cumbersome procedures for breaking and flushing, which increases operational risks and costs.
Innovation Solution
A temperature-responsive self-degradable temporary plugging agent is developed, composed of specific mass percentages of monomer, crosslinker, initiator, degradation catalyst, and chain transfer agent, which is liquid and easy to pump, crosslinks at reservoir temperature to form a gel plug, and degrades spontaneously, reducing the need for additional promoters or flushing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If liquid gel plug is used for well killing operations, then mechanical tools such as bridge plugs and packers can be replaced, but the viscosity increases quickly in a short time making it difficult to pump
Solution Approach 1:
The patent incorporates a temperature-responsive crosslinking mechanism that remains dormant during pumping but activates automatically upon entry into the wellbore at reservoir temperature. This preliminary preparation allows the gel to maintain low viscosity during pumping while forming a strong plug structure in-situ, resolving the contradiction between ease of pumping and viscosity stability.
Solution Approach 2:
The patent utilizes temperature as a controlling parameter to switch between two states: liquid state at surface conditions for easy pumping, and gel state at reservoir temperature for effective plugging. This parameter change enables the system to overcome the viscosity increase issue while maintaining operational effectiveness.
2Ease of operation
If existing liquid gel plug is used, then well killing operations can be performed, but the breaking and degradation of gel requires external forces and circulation flush, making the process complicated
Solution Approach 1:
The patent incorporates a self-degrading mechanism that automatically breaks down the gel plug after serving its purpose, eliminating the need for external breaking forces or circulation flush operations. The gel plug degrades spontaneously through controlled hydrolysis of the crosslinked structure, significantly simplifying the overall operation procedure.
Solution Approach 2:
The patent replaces mechanical breaking methods (requiring external forces and circulation systems) with a chemical self-degradation mechanism. This substitution eliminates the need for complex mechanical breaking operations and circulation flush procedures, reducing overall system complexity.
3Reliability
If mechanical plugging tools are used, then wellbore can be plugged, but tripping the pipe string is required which increases operational risks and costs
Solution Approach 1:
The patent replaces mechanical plugging tools (bridge plugs and packers) with a chemical gel plug system. This substitution eliminates the need for mechanical tripping operations and associated risks, while also simplifying the overall operation procedure by removing the need for tool setting and retrieval operations.
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
The agent forms a high-strength gel plug that can withstand differential pressures and degrades within 3-7 days, simplifying operations by eliminating the need for mechanical tools and flushing, while maintaining good fluidity and environmental friendliness.
Implementation Method 1
gel which can form a section of high strength viscoelastic plug in the wellbore based on the principle of high-concentration polymer solution crosslinking in the wellbore
Implementation Method 2
high-concentration polymer solution crosslinking in the wellbore
Implementation Method 3
degradation catalyst 0.05-0.1%
Data Source
AI summary
The present disclosure provides a temperature-responsive self-degradable temporary plugging agent and a preparation method thereof as well as its application in plugging the wellbore, which relates to the technical field of oilfield exploitation. The temporary plugging agent provided in the present disclosure includes preparation raw materials of the following mass percentages: monomer 4-6%, crosslinker 0.2-1%, initiator 0.02-0.06%, degradation catalyst 0.05-0.1%, chain transfer agent 0.01-0.05%, and the balance water. The temporary plugging agent of the present disclosure is liquid before gelling, with a low viscosity and a good fluidity, and easy to be pumped. When being pumped into the wellbore, the temporary plugging agent may crosslink at the temperature of the reservoir section, with good gelling properties. At the end of the operations, it can be degraded by itself, without drilling tools, with no need for gel breaking, and with no need for additional degradation promoters.