Single-Stage Acid Composition for Calcium-Free Siliceous Stimulation
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Solution Overview
Problem
Existing methods for acid treatment of siliceous formations face issues with calcium precipitation during and after treatment, leading to reduced fluid conductivity, and require multiple stages that increase fluid volume.
Innovation Solution
A single-stage acid treatment using an aqueous composition with a low molecular weight acid, HF source, and a fluoride scale inhibitor at a pH of 1.0 to 3.0, which inhibits calcium fluoride precipitation and enhances hydrocarbon extraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a calcium-removing fluid is used as pre-treatment, then calcium deposits are prevented, but the treatment requires multiple stages increasing fluid volume and complexity
Solution Approach 1:
The patent combines the calcium removal function and acid treatment function into a single integrated treatment fluid. The aqueous composition contains both calcium-removing agents (such as organic acids) and acid components (HF source), allowing both functions to be performed simultaneously in one stage rather than requiring separate pre-treatment and acid treatment stages.
Solution Approach 2:
The treatment fluid is designed to perform multiple functions simultaneously: it removes calcium, prevents calcium fluoride precipitation, and dissolves siliceous minerals. This multi-functional composition eliminates the need for sequential treatments and reduces the overall volume of fluids required.
2Reliability
If pre-treatment with calcium-removing fluid is used, then calcium precipitation is reduced, but the pre-treatment may not be precisely co-extensive with acid treatment resulting in calcium precipitation in untreated areas
Solution Approach 1:
By merging calcium removal and acid treatment into a single simultaneous process using one aqueous composition, the patent ensures uniform coverage across the entire treatment zone. The fluid performs both functions wherever it contacts the formation, eliminating the mismatch problem between pre-treatment and acid treatment boundaries.
Solution Approach 2:
The treatment fluid contains pre-formulated calcium-removing agents and scale inhibitors that are already present in the composition before injection. This preliminary preparation ensures that calcium is removed and precipitation is prevented throughout the entire acid treatment process, not just in areas covered by separate pre-treatment.
3Reliability
If multiple stages of treatment are used to prevent calcium precipitation, then calcium fluoride formation is controlled, but treatment time and fluid volume increase
Solution Approach 1:
The patent merges multiple treatment stages into a single simultaneous treatment using an integrated aqueous composition. The fluid contains calcium-removing agents, HF sources, and scale inhibitors that work together in real-time during one injection process, eliminating the time required for sequential treatments.
Solution Approach 2:
The treatment fluid maintains continuous action throughout the entire treatment process by containing all necessary components (calcium removers, acid, scale inhibitors) in a single composition. This continuous multi-functional action replaces discontinuous multi-stage treatments, reducing total treatment time while maintaining effectiveness.
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 effectively prevents calcium fluoride formation, increases permeability by up to 408%, reduces treatment stages to one, and decreases fluid volume, thereby improving hydrocarbon recovery efficiency.
Implementation Method 1
from about 0.1 wt % to about 2.0 wt % of a fluoride scale inhibitor... which inhibits calcium fluoride precipitation
Implementation Method 2
The acid dissolves, or otherwise removes, some mineral structures in the formation to improve hydrocarbon flow
Implementation Method 3
In the particular case of sandstones, which contain siliceous minerals, hydrogen fluoride (HF) is used in many forms to dissolve the silica materials
Implementation Method 4
The acid dissolves, or otherwise removes, some mineral structures in the formation to improve hydrocarbon flow
Data Source
AI summary
Methods and compositions for treating a siliceous geologic formation are described herein. An aqueous treatment composition for treating such formations includes a mixture of acids, an HF source, and a fluoride scale inhibitor. A pH of the aqueous treatment composition is between about 1.0 and about 3.0. The mixture of acids includes a first organic acid and a second organic acid and each acid of the mixture of acids has a non-zero, molecular weight less than 200 Daltons.