Thixotropic Drilling Fluid Gelation for Formation Sealing
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Solution Overview
Problem
Drilling fluids are often lost to the surrounding subterranean formation during drilling due to weak formations or structural defects, leading to decreased hydrostatic pressure and increased fluid requirements, which reduces efficiency and increases costs.
Innovation Solution
A thixotropic fluid composition is introduced, comprising an aqueous base fluid, a cross-linkable polymer, a cross-linking agent, a retarding agent, and a thixotropic agent, which exhibits non-Newtonian properties, allowing easy pumping but forming a gel in the wellbore to prevent fluid loss and maintain hydrostatic pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If drilling fluid is circulated to remove cuttings and lubricate drill components, then drilling operations can proceed, but fluid is lost to the surrounding formation through openings or cavities
Solution Approach 1:
The patent applies parameter changes by utilizing the temperature-dependent viscosity characteristics of drilling fluid. The fluid is pumped at high temperature downhole where it maintains low viscosity for easy circulation, then cools in the surface annulus to increase viscosity and form a gel that seals formations and prevents fluid loss
Solution Approach 2:
The patent implements periodic action through continuous circulation of drilling fluid that repeatedly passes through the hot wellbore and cooler surface annulus. This cyclic heating and cooling creates periodic viscosity changes that continuously seal formations and prevent fluid loss while maintaining drilling operations
2Stress or pressure
If more drilling fluid is pumped to compensate for losses, then hydrostatic pressure can be maintained, but fluid circulation requirements increase and costs rise
Solution Approach 1:
The patent changes the viscosity parameter of the drilling fluid through temperature-dependent gelation. The fluid transforms from a low-viscosity state during pumping to a high-viscosity gel state in the annulus, creating a plugging effect that reduces fluid loss and maintains hydrostatic pressure without requiring excessive fluid volumes
3Loss of substance
If drilling fluid viscosity is increased to prevent fluid loss to formation, then fluid loss is reduced, but pumping and circulation become more difficult
Solution Approach 1:
The patent uses periodic action by continuously cycling the drilling fluid through temperature zones that induce periodic viscosity changes. The fluid is pumped at low viscosity through the hot wellbore, then naturally gelates at lower temperatures in the annulus, creating a rhythmic pattern of fluid injection and gel formation that prevents loss without requiring high pumping pressures
Solution Approach 2:
The patent exploits parameter changes in viscosity as a function of temperature. The drilling fluid is designed to undergo a dramatic viscosity increase when cooled from downhole temperatures to surface temperatures, allowing the same fluid to be easily pumped during injection while forming a gel barrier during annular circulation
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 thixotropic composition effectively prevents drilling fluid loss by forming a gel in the wellbore, maintaining hydrostatic pressure and reducing the need for excessive fluid circulation, thereby enhancing drilling efficiency and reducing costs.
Implementation Method 1
A thixotropic fluid composition for inhibiting or preventing the loss of drilling fluid into the surrounding formation during drilling
Implementation Method 2
a cross-linkable polymer, a cross-linking agent for the cross-linkable polymer
Data Source
AI summary
A thixotropic composition having a cross-linkable polymer, cross-linking agent, initiator and a thixotropic agent. The thixotropic agent may be a clay or a saccharide polymer. The thixotropic composition may be introduced into a drill string via a batch or on-the-fly process to prevent loss of drilling fluid into the surrounding formation.