Borated Galactomannan Chemical Barrier for Zonal Isolation
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Solution Overview
Problem
Conventional methods for zonal isolation in wellbore operations are costly and require damaging or destroying zonal isolation assemblies for removal, and mechanical barriers often fail to provide effective seals under certain conditions.
Innovation Solution
A well treatment fluid containing borated galactomannan gum, which can be pumped unhydrated and crosslinked at the well site to form a temporary seal, allowing for controlled hydration and viscosity adjustment to isolate specific zones without the need for cement or mechanical packers, and can be removed using a viscosity reducing agent.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mechanical barriers or cementitious slurries are used for zonal isolation, then effective sealing can be achieved, but the assemblies must be damaged or destroyed for removal and costs increase
Solution Approach 1:
The chemical barrier uses reversible crosslinking chemistry where the gel structure can be transformed from a set state to a liquid state through chemical parameter changes (pH adjustment, temperature, or chemical additives), enabling removal without mechanical destruction
Solution Approach 2:
The invention employs a composite chemical system combining crosslinkable polymers, initiators, and modifiers that create a gel with both mechanical strength for sealing and chemical reversibility for removal, merging properties of structural integrity and ease of decomposition
2Strength
If conventional cementitious slurries are used to hold casing in place, then secure anchoring is achieved, but removal requires damage or destruction of the zonal isolation assembly
Solution Approach 1:
The chemical barrier's crosslinking density and mechanical properties can be modified by changing chemical parameters (pH, temperature, additive concentration), allowing the same material to provide strong anchoring during operation and then become removable through parameter adjustment
Solution Approach 2:
The invention replaces permanent mechanical anchoring systems with a chemically-bonded gel system that provides equivalent mechanical strength through chemical crosslinking but allows removal through chemical reversal rather than mechanical force
3Reliability
If mechanical packers are used for zonal isolation, then isolation can be established, but they are not capable of providing effective seals under certain conditions and increase device complexity
Solution Approach 1:
The invention replaces complex mechanical packer systems with a chemical gel system that establishes isolation through chemical crosslinking and volume expansion, eliminating moving parts, seals, and mechanical actuation mechanisms while providing reliable zonal isolation
Solution Approach 2:
The chemical barrier utilizes phase transition from liquid monomer to gel network through crosslinking, providing automatic seal establishment without mechanical adjustment, and can reverse to liquid state for removal, simplifying the isolation mechanism
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 effective zonal isolation and intervention in wellbore operations without damaging the formation, allowing for selective treatment of productive zones and efficient removal of the seal after use, reducing costs and minimizing formation damage.
Implementation Method 1
A well treatment fluid containing borated galactomannan gum, which can be pumped unhydrated and crosslinked at the well site to form a temporary seal
Implementation Method 2
a method of removing a chemical barrier from a well wherein a temporary seal defining the chemical barrier is removed by exposing the seal to a viscosity reducing agent
Data Source
AI summary
A well treatment fluid containing borated galactomannan may be used to isolate a pre-determined productive zone in an oil or gas well. The fluid is pumped into the well in a substantially non-hydrated form and forms a temporary seal. The fluid may be used as a chemical packer in place of a mechanical packer. After the pre-determined productive zone is isolated, a well intervention operation may be performed within the isolated pre-determined zone.