Composite Viscosifier for HTHP, High-Salinity Drilling Fluids
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Solution Overview
Problem
Existing drilling fluids face challenges in maintaining viscosity and preventing fluid loss due to high temperatures and high salinity, leading to ineffective filtercakes and increased formation permeation, which compromises drilling efficiency and formation integrity.
Innovation Solution
A drilling fluid comprising a viscosifier with a first component, a reaction product of acrylamide monomer and sulfonated anionic monomer, and a second component of styrene-butadiene polymer, which enhances viscosity and stability even in high temperature high pressure (HTHP) conditions and high salinity environments, forming a filtercake to prevent fluid loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If conventional viscosifiers (xanthan gum) are used to increase drilling fluid viscosity, then viscosity is improved, but effectiveness is reduced under high temperature and high salinity conditions
Solution Approach 1:
The patent modifies the chemical structure of the viscosifier by incorporating temperature-resistant and salinity-resistant functional groups into the polymer backbone. This changes the physical and chemical parameters of the viscosifier to maintain viscosity stability under HTHP conditions where conventional viscosifiers fail.
Solution Approach 2:
The patent uses a composite polymer structure combining multiple functional components - a temperature-resistant backbone with salinity-resistant side chains. This composite material approach allows the viscosifier to simultaneously resist both high temperature and high salinity effects that degrade conventional single-component viscosifiers.
2Force
If high concentration of salts is added to increase drilling fluid density, then density is improved, but stability and effectiveness of viscosifiers is reduced
Solution Approach 1:
The patent changes the chemical composition parameters of the viscosifier to include salt-tolerant functional groups that maintain polymer stability in high salinity environments. This allows the drilling fluid to have high density from salts while the viscosifier remains stable and effective.
Solution Approach 2:
The patent converts the harmful effect of high salinity (which normally degrades viscosifiers) into a beneficial condition by designing a viscosifier that thrives in high salt environments. The salinity-resistant structure allows the viscosifier to maintain effectiveness where conventional viscosifiers would fail.
3Loss of substance
If filtercake is formed to prevent fluid loss to formation, then fluid loss prevention is improved, but filtercake fails prematurely due to formation conditions
Solution Approach 1:
The patent modifies the rheological parameters of the drilling fluid using the improved viscosifier to form a filtercake with optimized strength and permeability characteristics. This ensures the filtercake can withstand premature failure conditions caused by formation stresses and chemical environments.
Solution Approach 2:
The patent creates a composite filtercake structure through the action of the composite viscosifier, which forms a more robust and chemically resistant cake that resists premature failure under challenging formation conditions.
4Loss of substance
If xanthan gum is used as fluid loss agent, then fluid loss is reduced, but viscosity stability under high temperature is compromised
Solution Approach 1:
The patent changes the chemical composition to use a temperature-resistant viscosifier that maintains viscosity stability at high temperatures while still providing fluid loss control through appropriate concentration and rheological properties.
Solution Approach 2:
The patent uses a single viscosifier component that performs multiple functions - both viscosity maintenance and fluid loss control - eliminating the need for separate xanthan gum additives and achieving both goals simultaneously under HTHP conditions.
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 viscosifier maintains fluid viscosity and forms an effective filtercake to reduce fluid loss, ensuring efficient cuttings lifting and wellbore integrity, while being removable post-drilling with a breaker fluid.
Implementation Method 1
the viscosity of the drilling fluid may be increased with a viscosifier (also referred to as a 'thickener')
Implementation Method 2
the drilling fluid may facilitate formation of a filtercake on surfaces of the formation to reduce or prevent permeation of fluids from entering the surrounding formation
Implementation Method 3
maintaining a sufficiently high viscosity of the drilling fluid may facilitate providing sufficient suspension and removal of cuttings by the drilling fluid
Data Source
AI summary
A drilling fluid for drilling a subterranean wellbore includes water, salt, and a viscosifier comprising a first component comprising a reaction product of at least one acrylamide monomer and at least one sulfonated anionic monomer, and a second component comprising styrene-butadiene polymer. Related methods of operating a wellbore and drilling fluids are claimed.