Foam Drilling Fluid Composition for Stable Underbalanced Drilling

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Solution Overview

Problem

Existing underbalanced drilling (UBD) techniques face challenges in maintaining foam stability in high pH and saline environments, leading to formation damage and reduced drilling efficiency.

Innovation Solution

A method using an ammonium alcohol ether sulfate surfactant-based foaming agent with a pH of 8 to 11, capable of forming stable foam with a high bubble count and area, and maintaining stability for extended periods in harsh drilling conditions, including high salinity and alkaline environments.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If conventional drilling mud is used to maintain wellbore pressure, then formation damage occurs due to invasion, but underbalanced drilling avoids formation damage by keeping wellbore pressure lower than formation pressure

Engineering Contradiction:

Improveformation damageVSAvoidwellbore pressure

Core Design Contradiction:

Object-affected harmful factorsVSStress or pressure

Solution Approach 1:

The invention changes the physical and chemical parameters of the drilling fluid by using foam instead of conventional liquid mud. The foam's gas-liquid structure fundamentally alters density, viscosity, and pressure transmission characteristics, enabling underbalanced drilling while maintaining effective cuttings transport

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention utilizes phase transition by introducing gas bubbles into the liquid drilling fluid to create a two-phase foam system. This phase transition from single-phase liquid to two-phase gas-liquid foam fundamentally changes the fluid's mechanical properties and pressure behavior

Inventive Principle:

Principle #36Phase transitions

2Stability of the object's composition

If foam drilling is used to reduce formation damage, then foam stability becomes challenging in high salinity and alkaline environments, but stable foam is needed for effective cuttings transport

Engineering Contradiction:

Improvefoam stabilityVSAvoidadaptability to harsh environments

Core Design Contradiction:

Stability of the object's compositionVSAdaptability or versatility

Solution Approach 1:

The invention modifies the chemical composition parameters of the foaming agent to be specifically adapted for high salinity and alkaline conditions. The foaming agent's molecular structure and concentration are optimized to maintain surface tension and foam stability in harsh drilling environments

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention creates a composite foam system combining gas, liquid, and specially formulated foaming agent. This composite structure provides both the stability needed for harsh environments and the functionality for cuttings transport, with each component contributing specific properties

Inventive Principle:

Principle #40Composite materials

3Stability of the object's composition

If dry drilling foam is used to improve hole cleaning, then foam stability increases due to rigid liquid film structure, but foam generation complexity increases

Engineering Contradiction:

Improvefoam stabilityVSAvoidfoam generation complexity

Core Design Contradiction:

Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The invention optimizes the liquid content parameter within the 5-30% range to achieve the transition from wet to dry foam. This parameter control creates the rigid polyhedral liquid film structure characteristic of dry foam, providing enhanced stability and hole cleaning capability

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 method enhances foam stability, preventing formation damage and improving drilling efficiency by maintaining a stable foam structure, facilitating effective cuttings transport and reducing fluid loss.

Implementation Method 1

The foaming agent is an aqueous solution that comprises an ammonium alcohol ether sulfate surfactant

Methodology Applied

Scientific EffectSurfactant: Surfactant

Implementation Method 2

The foaming agent forms a foam in the wellbore at a drilling surface at a bottom of the wellbore

Methodology Applied

Scientific EffectFoam: Foam

Implementation Method 3

A desired foam has a low density and high viscosity to help transport cuttings to the surface

Methodology Applied

Scientific EffectBuoyancy: Archimedes' Principle (Buoyancy)

Implementation Method 4

transporting drill cuttings formed by the drilling away from the drilling surface in the foam

Methodology Applied

Scientific EffectFluid flow: Convection

Data Source

PatentUS12509952B2Method of underbalanced drilling using foaming agent

Publication Date: 2025.12.30 KING FAHD UNIVERSITY OF PETROLEUM AND MINERALS

AI summary

A method for underbalanced drilling includes drilling into a subterranean geological formation to form a wellbore therein, injecting a foaming agent into the wellbore during drilling at a wellbore pressure that is below a pore pressure of the subterranean geological formation, and transporting drill cuttings formed by the drilling away from the drilling surface in the foam. The foaming agent forms a foam in the wellbore at a drilling surface at a bottom of the wellbore. The foaming agent is an aqueous solution including an ammonium alcohol ether sulfate surfactant.