Acid Spearhead Formulation Mitigates Barite Scale in Shale Systems

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Solution Overview

Problem

Hydraulic fracturing systems face significant challenges due to barite scale formation, which reduces permeability and oil/gas production, primarily caused by the instability of barite in drilling mud and its precipitation in the rock matrix, with existing methods failing to effectively mitigate this issue.

Innovation Solution

A novel acid spearhead formulation combining sulfuric acid and sodium citrate is introduced, which stabilizes barite and reduces gypsum formation, allowing for controlled barite dissolution and transport, thereby preventing barite scale precipitation in the rock volume.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If hydrochloric acid is injected to increase rock permeability during hydraulic fracturing, then the overall permeability of rock is improved, but barite in drilling mud becomes unstable and precipitates as barite scale in the rock matrix, reducing permeability

Engineering Contradiction:

Improvebarite stabilityVSAvoidrock permeability

Core Design Contradiction:

Stability of the object's compositionVSProductivity

Solution Approach 1:

Sulfuric acid serves as an intermediary substance that replaces hydrochloric acid in the acid spearhead formulation. It provides the necessary acidity to dissolve carbonate minerals and increase rock permeability while simultaneously stabilizing barite through common ion effect, preventing barite scale precipitation and maintaining productivity

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention changes the chemical parameter of the acid from hydrochloric acid to sulfuric acid. This parameter change fundamentally alters the interaction with barite, transforming it from an unstable condition causing scale precipitation to a stable condition that prevents scaling while maintaining the desired permeability enhancement effect

Inventive Principle:

Principle #35Parameter changes

2Reliability

If drilling mud containing barite is used for well bore stabilization, then well bore stability is improved, but barite precipitates in the rock matrix reducing permeability and oil/gas production

Engineering Contradiction:

Improvewell bore stabilityVSAvoidbarite scale formation

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The invention converts the harmful effect of barite instability into a beneficial outcome. By using sulfuric acid in the acid spearhead, the barite that would normally precipitate as scale is instead stabilized through common ion effect. The same barite that causes harm in conventional treatments becomes part of the stabilization mechanism, eliminating scale formation while maintaining well bore stability

Inventive Principle:

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

Solution Approach 2:

The acid spearhead formulation uses a composite acid system (sulfuric acid) that performs multiple functions simultaneously: it stabilizes barite through common ion effect, dissolves carbonate minerals to create permeability, and prevents barite scale formation. This single composite material replaces the need for separate treatment steps

Inventive Principle:

Principle #40Composite materials

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 formulation effectively stabilizes barite, reducing barite scale formation by up to 90% and maintaining permeability, enhancing oil/gas production by preventing barite and sulfate precipitation in the rock matrix.

Implementation Method 1

stabilizing barite (barium sulfate) contained in drilling mud which is released into solution during current stimulation practices

Methodology Applied

Scientific EffectCommon ion effect:

Implementation Method 2

an acid spearhead formulation for mineral scale reduction that includes a sulfuric acid solution having an acidity that is operationally equivalent to a hydrochloric acid solution in a acid spearhead formulation, with the addition of a sodium citrate compound

Methodology Applied

Scientific EffectChelation:

Implementation Method 3

the acidity of injected fluid required to increase the overall permeability of rock during hydraulic fracturing

Methodology Applied

Scientific EffectChemical dissolution:

Data Source

PatentUS11187051B2Fracture fluid alteration to mitigate barite scale precipitation in unconventional oil/gas shale systems

Publication Date: 2021.11.30 THE BOARD OF TRUSTEES OF THE LELAND STANFORD JUNIOR UNIV

AI summary

An acid spearhead formulation for mineral scale reduction that includes a sulfuric acid solution having an acidity that is substantially equivalent to a hydrochloric acid solution in an acid spearhead formulation, a sodium citrate compound, where an acid spearhead formulation for mineral scale reduction is formed, the acid spearhead formulation is disposed in a well bore to stabilize mineral scales, the acid spearhead formulation is disposed in the well bore to chelate solubilized calcium in a rock bed of the well bore, and the well bore includes a temporal thermodynamic subsurface barite cycling having a subsurface barite dissolution temporal phase, a subsurface barite transport to fractures temporal phase, a subsurface barite precipitation to fracture temporal phase and a subsurface barite dissolution to fracture space temporal phase, where the acid spearhead formulation for mineral scale reduction reacts with the well bore within the subsurface barite dissolution temporal phase.