pH-Responsive Polymer Gel for Well Treatment Cleanup
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Solution Overview
Problem
Conventional cross-linked gelling agents used in well treatments are difficult to remove completely, leading to reduced formation permeability and prolonged cleanup periods, especially in lower temperature wells and high-temperature formations.
Innovation Solution
A polymer or polymer system capable of forming a gel at middle pH and dissolving at low and high pH levels, primarily through electrostatic cross-linking, is used to create a treatment gel that can be adjusted in pH to facilitate its dissolution and removal from the well.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional cross-linked gelling agents are used in well treatments, then the gel provides effective treatment functionality, but the gel becomes difficult to remove completely, leading to reduced formation permeability and prolonged cleanup periods
Solution Approach 1:
The gel system transitions from a static cross-linked structure to a dynamic pH-responsive system. The gel forms at neutral pH for effective treatment, then automatically dissolves when pH is adjusted to acidic or basic conditions, enabling complete removal without prolonged cleanup operations.
Solution Approach 2:
The patent utilizes pH parameter changes to control gel formation and dissolution. By adjusting the pH of the treatment fluid to extreme values (acidic or basic), the gel structure is destabilized and completely dissolved, solving the removal problem associated with conventional gelling agents.
2Strength
If conventional cross-linked gelling agents are used, then the gel maintains structural integrity during treatment, but additional cross-linking agents are required which complicates the cleanup process
Solution Approach 1:
The patent extracts the cross-linking mechanism from separate chemical additives and integrates it into the gel polymer structure itself through pH-responsive electrostatic interactions. This eliminates the need for additional cross-linking agents and simplifies the cleanup process by allowing simple pH adjustment for complete dissolution.
Solution Approach 2:
The gel system is self-cross-linking through electrostatic interactions between charged groups in the polymer structure when at neutral pH. The same electrostatic interactions are reversed by pH change, causing automatic dissolution without requiring external breaking agents or complex cleanup chemicals.
3Stability of the object's composition
If the gel is designed to be stable across a wide pH range, then it provides consistent performance, but it becomes difficult to dissolve and remove from the well
Solution Approach 1:
The gel exhibits different properties at different pH levels: stable and cross-linked at neutral pH for effective treatment, but labile and dissolvable at acidic or basic pH. This local quality change allows the gel to be stable during operation yet easily removed through simple pH adjustment.
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 approach allows for effective cleanup of the treatment gel without the need for additional cross-linking agents, improving permeability restoration and reducing cleanup time by adjusting the pH to break the electrostatic cross-links, enabling efficient removal of the gel residue.
Implementation Method 1
A polymer or polymer system capable of forming a gel at middle pH and dissolving at low and high pH levels, primarily through electrostatic cross-linking
Implementation Method 2
adjusting the pH to break the electrostatic cross-links, enabling efficient removal of the gel residue
Data Source
AI summary
Methods for treating a portion of a well include the steps of: (a) forming a treatment gel comprising a polymer or a polymer system of a mixture of two or more polymers, wherein the polymer or the polymer system is capable of each of the following, when tested at at least one concentration in the range of 2-10 times C* in deionized water, at about 22° C., and at about 1 atmosphere pressure: (i) forming a polymer gel of the polymer and water at at least one pH in the range of 4-9, wherein a bulk form of the polymer gel has a G′ greater than G″ at all frequencies in the range of 1 rad/sec-100 rad/sec; (ii) dissolving at at least one pH in the range of 2-4; and (iii) dissolving at at least one pH in the range of 9-12; (b) dispersing the treatment gel in a fluid to form a treatment fluid; (c) introducing the treatment gel in a treatment fluid into a portion of a well; and (d) after the step of introducing the treatment gel, adjusting the pH of the treatment gel to at least one pH in the range of 2-4 or 9-12.