Acid-Soluble Cement and Polymer Gel Plugging
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Solution Overview
Problem
Current compositions used for plugging subterranean formations struggle to effectively control fluid production in high permeability reservoirs and fractures, as they lack the necessary strength and stability to withstand high pressure gradients and temperature conditions, and cannot be easily removed once set.
Innovation Solution
A cement composition combining acid-soluble cement with a mixture of high and low molecular weight polymers, including polyacrylamide, which can be formulated to set within subterranean formations and later dissolved with acid, providing improved mechanical and thermal stability and allowing for effective plugging and un-plugging of zones.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polymer gels are used to plug subterranean formations, then fluid production can be controlled, but the compositions lack the necessary strength and stability to withstand high pressure gradients and temperature conditions
Solution Approach 1:
The patent combines polymer gels with acid-soluble cement to create a composite plugging composition. The polymer gel provides fluid control and sealing properties, while the acid-soluble cement adds structural strength and stability to withstand high pressure gradients and temperature conditions. This composite approach resolves the contradiction by integrating materials with complementary properties.
2Strength
If cement is used to plug zones, then strength and stability are improved, but the cement cannot be easily removed once set
Solution Approach 1:
The patent uses acid-soluble cement that changes its solubility parameters based on chemical environment. The cement maintains strength and stability under normal reservoir conditions but becomes soluble when exposed to acid, allowing for easy removal or adjustment if needed. This parameter change enables both strength during operation and ease of repair when required.
3Reliability
If high molecular weight polymers are used alone, then plugging effectiveness is improved, but the compositions cannot withstand high pressure gradients
Solution Approach 1:
The patent combines high molecular weight polymers with acid-soluble cement to create a composite system. The high molecular weight polymer provides effective plugging by forming a gel structure that blocks fluid flow, while the acid-soluble cement provides the necessary structural strength to withstand high pressure gradients. The composite material integrates the advantages of both components.
4Ease of manufacture
If current plugging compositions are used in high permeability reservoirs, then treatment is simpler, but the compositions lack the necessary stability under high temperature conditions
Solution Approach 1:
The patent uses a composite of polymer gel and acid-soluble cement that maintains thermal stability in high temperature reservoirs. The acid-soluble cement component provides thermal resistance while the polymer gel maintains plugging effectiveness. This composite approach allows the treatment to remain relatively simple while achieving the necessary thermal stability for high temperature applications.
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 cement composition effectively plugs zones with enhanced strength and stability, capable of withstanding high pressures and temperatures, and can be easily removed using acid, thereby improving hydrocarbon well performance and minimizing water production.
Implementation Method 1
Acid-soluble cement can be readily removed by injecting hydrochloric acid into a production zone
Implementation Method 2
Polymer gels can be used as a diverting or blocking agent in the treatment of injection and production wells
Data Source
AI summary
Compositions and methods for plugging a zone of a subterranean formation includes a cement composition having an acid soluble cement, a low molecular weight polymer, a high molecular weight polymer, and water. The acid soluble cement is in amount in a range of 10% to 50% by weight of the composition.