Solid Acid-precursor Fracturing Fluid with Scale Inhibitor Protection
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Solution Overview
Problem
Current acid fracturing methods face challenges such as rapid acid reaction near the wellbore, corrosion of equipment, and ineffective scale inhibition, leading to reduced well productivity and frequent treatment requirements due to rapid decline in scale inhibitor concentration.
Innovation Solution
A treatment fluid comprising a carrier fluid, a solid acid-precursor that hydrolyzes to form acid in situ, and solid scale inhibitor particles, which are designed to delay acid generation and maintain scale inhibition over time, reducing corrosion and extending treatment effectiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If direct acid fluids are utilized in acid fracturing, then acid reacts quickly near the wellbore to etch flowpaths, but acid fails to penetrate deeply into the formation and causes excessive corrosion of metal parts
Solution Approach 1:
The patent applies preliminary action by pre-coating proppant particles with scale inhibitor materials before injection. This pre-prepared coating ensures that scale inhibition is immediately available when the acid reaches the formation, allowing deeper penetration without corrosion damage to downhole equipment. The scale inhibitor is already in position to protect metal surfaces before acid contact occurs.
Solution Approach 2:
The patent uses scale inhibitor-coated proppant particles as an intermediary between the acid fluid and metal equipment. The proppant particles carry the scale inhibitor to the formation, where they release the inhibitor to form a protective film on metal surfaces, preventing direct contact between acid and equipment while allowing acid to penetrate deeply into the formation.
2Reliability
If scale inhibitor chemical is injected into formation with flushing fluid, then scale inhibition is provided initially, but scale inhibitor concentration declines rapidly and treatment must be repeated often
Solution Approach 1:
The patent achieves continuity of useful action by embedding scale inhibitors in proppant particles that continuously release the inhibitor over time. As proppant particles are carried into the formation and settle in the fracture, they progressively release scale inhibitor, maintaining continuous protection rather than a single initial dose that depletes quickly. This extends the effective duration of scale inhibition.
Solution Approach 2:
The proppant particles serve a dual function: they prop open the fracture and simultaneously act as carriers for scale inhibitors. The particles self-release the scale inhibitor in a controlled manner as they reside in the formation, providing self-sustaining scale protection without requiring additional injection operations. The treatment system serves itself by incorporating the inhibitor delivery mechanism within the proppant.
3Duration of action of moving object
If acid precursors in liquid phase are used to form acid in wellbore, then acid is generated in situ, but acid reacts very quickly and limits the delay effect
Solution Approach 1:
The patent changes the physical state parameter of the acid precursor from liquid to solid form. Solid acid precursors in the proppant coating dissolve and react more slowly than liquid acid precursors, providing a controlled delay in acid generation. This parameter change allows the acid to be generated progressively as proppant particles dissolve, extending the duration of acid action while maintaining penetration depth.
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 solution allows for deeper acid penetration and prolonged scale inhibition, reducing the need for frequent treatments and minimizing equipment corrosion, thereby enhancing well productivity and treatment efficiency.
Implementation Method 1
a solid acid-precursor that hydrolyzes to form acid in situ
Implementation Method 2
solid scale inhibitor particles, which are designed to delay acid generation and maintain scale inhibition over time
Data Source
AI summary
A method for treating a subterranean formation includes forming a treatment fluid including a carrier fluid, a solid acid-precursor, and a solid scale inhibitor. The solid acid-precursor includes a material that forms an acid at downhole conditions in the subterranean formation. The method further includes adding a solid acid-responsive material into the treatment fluid, where the solid acid-responsive material enhances formation of acid from the solid acid-precursor in acidic conditions. The method includes performing an acid fracture treatment and inhibiting scale formation within the subterranean formation. The solid scale inhibitor allows for long-term scale inhibition after the treatment.