Hydratable Polymer Slurry for Selective Water Control
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Solution Overview
Problem
Current methods for controlling unwanted water production in hydrocarbon reservoirs, especially in naturally fractured carbonate or sandstone reservoirs, are non-selective and often shut off both oil and water production due to the lack of controllable and selective placement of crosslinked gels.
Innovation Solution
A water-free slurry comprising a non-aqueous carrier fluid, a suspension agent with a mineral clay mixture, and a hydratable polymer is injected into the wellbore, which only crosslinks and forms a rigid gel in the presence of formation water, selectively plugging the target zone without affecting oil production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If crosslinked gels are used to control water production, then water production is reduced, but oil production is also shut off due to non-selective placement
Solution Approach 1:
The polymer slurry is designed to have different properties in different zones - it remains soluble and flowable in the injection zone (non-aqueous environment) but crosslinks and forms a gel only in the water-bearing zone (aqueous environment). This local differentiation of physical state enables selective water control without affecting oil production zones.
Solution Approach 2:
The crosslinking of the polymer is controlled by changing the chemical environment parameter - specifically, the presence or absence of water. The polymer transitions from a soluble state in non-aqueous carrier fluid to a crosslinked gel state upon contact with formation water. This parameter-driven transformation enables selective placement and activation of the plug only in water-bearing intervals.
2Object-affected harmful factors
If rigid gels are placed in water-bearing intervals, then water production is controlled, but the placement selectivity and controllability are insufficient
Solution Approach 1:
The polymer is pre-solubilized in a non-aqueous carrier fluid before injection, ensuring it remains in a flowable, injectable state during pumping. The crosslinking action is postponed until the slurry reaches the target zone and contacts formation water, at which point the gel forms only in the water-bearing intervals. This temporal separation of solubilization and crosslinking enables precise control over placement location and timing.
Solution Approach 2:
The non-aqueous carrier fluid acts as an intermediary medium that transports the polymer to the target zone without causing premature crosslinking. It provides a temporary soluble state for the polymer, allowing controlled delivery into the formation. Upon contact with formation water, the intermediary carrier fluid is displaced and the polymer crosslinks, forming the gel plug only where needed.
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 selective shut-off of unwanted water production intervals while maintaining permeability for oil production, providing a more controlled and effective solution compared to existing methods.
Implementation Method 1
a hydratable polymer... which only crosslinks and forms a rigid gel in the presence of formation water
Implementation Method 2
a suspension agent with a mineral clay mixture
Data Source
AI summary
A water-free slurry may include a non-aqueous carrier fluid; a suspension agent including a mineral clay mixture; a crosslinking agent; and a hydratable polymer. A method of treating a subterranean formation may include injecting a water-free slurry into a wellbore penetrating the subterranean formation, the water-free slurry including: a non-aqueous carrier fluid; a suspension agent comprising a mineral clay mixture; a crosslinking agent; and a hydratable polymer.