Polysaccharide Drilling Fluid Gel Structure for Wellbore Stability

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Solution Overview

Problem

Conventional clay-based drilling fluids used in horizontal directional drilling are costly and pose environmental concerns due to disposal issues, and they often fail to provide adequate gel strength and fluid loss control, leading to wellbore instability and stuck drill pipes, especially in unconsolidated formations.

Innovation Solution

A sustainable, polysaccharide-based drilling fluid utilizing naturally occurring iota carrageenan, partially hydrolyzed polyacrylamide, and divalent cations like calcium ions, which forms a gel structure to enhance gel strength and fluid loss control without the need for clay, thereby stabilizing the wellbore and preventing pipe sticking.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If clay-based drilling fluids are used, then gel strength is provided to suspend cuttings, but fluid loss control deteriorates and wellbore instability occurs

Engineering Contradiction:

Improvegel strengthVSAvoidfluid loss

Core Design Contradiction:

StrengthVSLoss of substance

Solution Approach 1:

The patent changes the chemical composition parameters by replacing clay-based polymers with polysaccharide-based polymers (specifically hydrolyzed polyacrylamide and xanthan gum). This substitution maintains gel strength through different molecular mechanisms while improving fluid loss control properties, directly resolving the contradiction between these two parameters.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs a composite polymer system combining hydrolyzed polyacrylamide and xanthan gum in specific proportions. This composite approach creates synergistic effects where the combination of polymers provides both adequate gel strength and superior fluid loss control, overcoming the limitations of single-component clay-based systems.

Inventive Principle:

Principle #40Composite materials

2Reliability

If clay-based drilling fluids are used, then cuttings suspension is achieved, but environmental harm increases due to disposal issues

Engineering Contradiction:

Improvecuttings suspensionVSAvoidenvironmental harm

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent adopts biodegradable polysaccharide polymers that can be environmentally disposed of after use. These polymers naturally decompose in the environment, eliminating the long-term environmental persistence and disposal problems associated with clay-based drilling fluids, while maintaining functional reliability during the drilling operation.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent converts the potential harm of polymer degradation into a benefit by selecting polysaccharide-based polymers that degrade into harmless natural products. The degradation process, which would normally be considered a loss of functionality, actually provides environmental benefit by eliminating persistent contaminants while the polymers remain fully functional during the drilling operation.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Use of energy by moving object

If water-based drilling fluid is used, then cooling and lubrication functions are provided, but filter cake buildup causes stuck drill pipe

Engineering Contradiction:

Improvecooling and lubricationVSAvoidstuck drill pipe prevention

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent modifies the fluid loss control parameters by optimizing polymer concentration and composition to create a filter cake with appropriate permeability. This controlled filter cake allows water to pass through for cooling and lubrication functions while preventing excessive buildup that would cause drill pipe sticking, thus resolving the contradiction between these two reliability aspects.

Inventive Principle:

Principle #35Parameter changes

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 iota carrageenan-based drilling fluid provides effective gelation and filtration control across a range of temperatures, maintaining wellbore stability and preventing pipe sticking, while being environmentally friendly and biodegradable, thus addressing the limitations of traditional clay-based fluids.

Implementation Method 1

Methodology Applied

Scientific EffectGelation: Gel

Implementation Method 2

Another important function of drilling fluid is to provide a thin and impermeable filter cake on the wall of the wellbore to reduce loss of water from the wellbore to the formation

Methodology Applied

Scientific EffectFiltration: Filter (physical)

Data Source

PatentUS10400153B2Drilling fluid for use in horizontal directional drilling operations

Publication Date: 2019.09.03 HALLIBURTON ENERGY SERVICES INC

AI summary

Methods of circulating a drilling fluid while drilling a shallow wellbore that is highly deviated or horizontal. The drilling fluid comprises an aqueous base fluid, iota carrageenan, partially hydrolyzed polyacrylamide, and a divalent cation selected from the group consisting of a calcium ion, a magnesium ion, and any combination thereof. The shallow wellbore that is highly deviated or horizontal is no greater than about 610 meters below an earth surface, and in a range of about 55.degree. to about 125.degree. from a vertical inclination.