Sealant Composition Gel System Permeable Zone Plugging
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Solution Overview
Problem
Current methods for plugging permeable zones in wellbores, such as squeeze cementing and polymer gel treatments, face limitations including short gel time due to high temperatures and alkalinity of cement, leading to premature hardening and inadequate penetration into porous rock, and excessive leak-off into the formation.
Innovation Solution
A sealant composition comprising a gel system, a leak-off prevention material, and water, with adjustable crosslinker amounts to extend gel time and reduce leak-off, using materials like cement, silica flour, or starch to control gel placement and prevent fluid loss beyond desired depths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If cement is used for squeeze cementing, then mechanical strength and ability to fill voids is improved, but gel time becomes unacceptably short at high temperatures leading to premature hardening
Solution Approach 1:
A gel system acts as an intermediary between the cement and the formation. The gel system is pumped first to penetrate the formation and provide in-depth blockage, then the cement is placed to provide mechanical strength and seal voids. This intermediary approach allows each material to perform its optimal function without the limitations of using either alone.
Solution Approach 2:
The gel system is placed in the formation before the cement. This preliminary action allows the gel to penetrate the porous media and establish a blockage pathway, ensuring that when the cement is subsequently placed, it has extended gel time to reach the permeable zone and properly seal the formation without premature hardening.
2Length of moving object
If polymer gel is used for shutting production, then in-depth penetration into porous media is improved, but mechanical properties are insufficient to provide resistance to flow in voids and cavities
Solution Approach 1:
The invention combines polymer gel and cement into a single treatment sequence. The gel component provides in-depth penetration into porous media through its ability to flow and crosslink in situ, while the cement component provides the necessary mechanical strength to resist flow in voids and cavities. The two materials work synergistically to overcome the limitations of each when used separately.
3Strength
If sequential gel then cement treatment is used, then both penetration depth and mechanical strength are improved, but permanent shut-off may occur beyond perforation depth
Solution Approach 1:
The gel system is placed first as a preliminary action to create a controlled blockage in the formation. The gel's viscosity and crosslinking properties are adjusted to limit its invasion depth to match the perforation depth. Following this, the cement is placed to provide the final seal, ensuring that the combined treatment achieves the desired shut-off without permanent blockage beyond the intended zone.
4Loss of substance
If gel is used as mix water for cement slurry, then controlled leak-off into porous medium is improved, but gel time becomes unacceptably short at high temperatures
Solution Approach 1:
The gel system serves as an intermediary placement material that controls leak-off during the cement squeezing process. By placing the gel first, it creates a controlled barrier that limits cement leak-off into the formation. The gel's placement time and leak-off characteristics are optimized to work in conjunction with the subsequent cement placement, ensuring controlled fluid loss while maintaining adequate handling time.
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 sealant composition effectively plugs permeable zones by maintaining pumpability at high temperatures, ensuring proper placement, and reducing fluid loss, thereby enhancing zonal isolation and preventing unwanted fluid flow.
Implementation Method 1
polymer gels provide in depth blockage of the formation by penetrating the porous media and crosslinking in situ therein
Implementation Method 2
The limited and controlled leak off of the polymer gel into the porous medium during the squeeze enables a controlled depth of invasion
Implementation Method 3
adjustable crosslinker amounts to extend gel time and reduce leak-off
Data Source
AI summary
A sealant composition for servicing a wellbore comprising at least one gel system, a leak off prevention material and water.