Non-Polymeric Silica Scale Control Additives in Acidic Treatment Fluids
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Solution Overview
Problem
Silica scale deposition in subterranean formations during acidizing treatments is challenging due to the precipitation of amorphous, gelatinous, and colloidal silica, which can lead to porosity reduction and formation damage, especially in formations with siliceous and aluminosilicate minerals, and conventional silica scale control additives are ineffective in addressing short-term oligomerization processes.
Innovation Solution
A treatment fluid with a pH of 6 or less, comprising an acidic base fluid and a non-polymeric silica scale control additive such as tannic acid or ortho-dihydroxybenzene compounds, is introduced into the subterranean formation to retard silica scale deposition by inhibiting silicic acid oligomerization and increasing the solubility of dissolved silicon, thereby preventing the formation of insoluble silica precipitates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional silica scale control additives are used, then silica scale deposition is controlled at circumneutral pH, but they are ineffective at acidic pH values and cannot address short-term oligomerization processes
Solution Approach 1:
The patent changes the chemical structure parameter of silica scale control additives from polymeric to non-polymeric forms, specifically using compounds with ortho-dihydroxybenzene units. This structural parameter change enables the additives to function effectively across a broad pH range including acidic conditions (pH 2-6), and allows them to inhibit both oligomerization and deposition processes that conventional additives cannot address
2Reliability
If strong acids are used to remove silica scale buildup, then silica scale is effectively removed, but formation damage occurs in acid-sensitive formations and treatment cost increases
Solution Approach 1:
The patent applies preliminary anti-action by using non-polymeric silica scale control additives to prevent silica scale deposition in the first place during acidizing treatments. By inhibiting the oligomerization and deposition of silicic acid at acidic pH values, the treatment prevents scale buildup before it occurs, eliminating the need for subsequent strong acid removal treatments that would cause formation damage
Solution Approach 2:
The patent converts the harmful effect of dissolved silicon precipitation into a beneficial outcome by using ortho-dihydroxybenzene compounds that form soluble complexes with silicon species. This complexation keeps silicon in solution even at circumneutral pH values, preventing scale deposition while allowing the use of acidic base fluids in siliceous formations
3Productivity
If acidic base fluids are used in subterranean formations with siliceous minerals, then stimulation treatment is effective, but dissolved silicon precipitates at higher pH values forming silica scale
Solution Approach 1:
The patent introduces non-polymeric silica scale control additives containing ortho-dihydroxybenzene units as intermediary compounds that mediate between the acidic base fluid and siliceous formation minerals. These additives form soluble complexes with dissolved silicon species, acting as a bridge that prevents direct precipitation of silica scale while allowing the acidic treatment to proceed effectively in siliceous formations
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 use of non-polymeric silica scale control additives effectively maintains high concentrations of dissolved silicon over a broad pH range, preventing silica scale buildup and allowing for continuous well operations without the need for strong acids, which are often detrimental to acid-sensitive formations.
Implementation Method 1
non-polymeric silica scale control additive such as tannic acid or ortho-dihydroxybenzene compounds, is introduced into the subterranean formation to retard silica scale deposition by inhibiting silicic acid oligomerization and increasing the solubility of dissolved silicon
Implementation Method 2
non-polymeric silica scale control additive such as tannic acid or ortho-dihydroxybenzene compounds, is introduced into the subterranean formation to retard silica scale deposition by inhibiting silicic acid oligomerization
Data Source
AI summary
Treatment fluids may be used to retard the deposition of silica scale in subterranean formations. Methods for treating a subterranean formation can comprise providing a treatment fluid having a pH of 6 or less that comprises an acidic base fluid and a non-polymeric silica scale control additive, and introducing the treatment fluid into at least a portion of a subterranean formation. The non-polymeric silica scale control additive retards deposition of silica scale in the subterranean formation.