Polyamide Emulsion Stabilizers for Shale-Swelling Control
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Solution Overview
Problem
Existing emulsion stabilizing agents used in oil-based muds (OBMs) increase the swelling and dispersion of shales, leading to wellbore instability during subterranean treatments, while water-based muds (WBMs) cause wellbore collapse in water-sensitive formations.
Innovation Solution
Development of polyamides formed by reacting C6-C30 aliphatic monocarboxylic acids or esters with polyamines, followed by unsaturated dicarboxylic acids or anhydrides, and curing at 130-200°C to increase molecular weight, reducing shale interaction and enhancing emulsion stability and rheology.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If traditional emulsion stabilizing agents (surfactants) are used in oil-based muds, then emulsion stability is improved, but shale swelling and dispersion increases leading to wellbore instability
Solution Approach 1:
The patent changes the molecular weight parameter of the polyamide from conventional ranges to greater than 1700 Da, and adjusts the fatty acid to polyamine molar ratio to 0.5-2.0:1. These parameter changes fundamentally alter the polyamide's interaction with shale, reducing swelling and dispersion while maintaining emulsion stability.
Solution Approach 2:
The patent creates a composite emulsion system combining water-in-oil emulsion with specifically engineered high molecular weight polyamides. This composite approach integrates multiple functional properties: emulsification, shale inhibition, and rheology control, resolving the contradiction between emulsion stability and shale stability.
2Ease of manufacture
If water-based muds are used to reduce cost and environmental impact, then cost effectiveness and environmental friendliness are improved, but wellbore collapse occurs in water-sensitive formations
Solution Approach 1:
The patent uses water-in-oil emulsion as an intermediary system that combines benefits of both water-based and oil-based muds. The continuous oil phase provides shale inhibition and wellbore stability, while the dispersed aqueous phase enables cost-effectiveness and environmental benefits, acting as a mediator between conflicting requirements.
3Object-affected harmful factors
If polyamides with molecular weight >1700 Da are used, then shale swelling and dispersion are reduced, but emulsifying capability must be maintained
Solution Approach 1:
The patent optimizes the fatty acid to polyamine molar ratio parameter to 0.5-2.0:1, which ensures sufficient hydrophobic and hydrophilic groups are present to maintain emulsifying capability even at high molecular weights (>1700 Da). This parameter optimization resolves the contradiction between reduced shale interaction and maintained emulsification.
4Stability of the object's composition
If high molecular weight polyamides are used to reduce shale interaction, then wellbore stability is improved, but fluid rheology must be maintained at high temperatures
Solution Approach 1:
The patent creates a composite system where high molecular weight polyamides provide thermal stability and shale inhibition, while the water-in-oil emulsion structure maintains fluid rheology. The interconnected network of the emulsion and polyamide composite provides both wellbore stability and temperature-resistant flow properties.
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 new polyamides significantly reduce shale swelling and dispersion, maintaining wellbore stability and fluid integrity even at high temperatures, without additional emulsifiers, thus improving the performance of water-in-oil subterranean treatment fluids.
Implementation Method 1
reacting a) one mole of a polyamine having n amino groups with exchangeable hydrogens, wherein n is an integer ranging from 3 to 5; b) from n/2 to n-0.8 moles of a C6-C30 saturated or unsaturated aliphatic monocarboxylic acid or an ester thereof or mixtures thereof; to obtain an aminoamide characterized by a saponification number below 30 mgKOH/g
Implementation Method 2
reacting the aminoamide with: c) from 0.4 to 1.1 moles of a C4-C6 unsaturated dicarboxylic acid or with the corresponding anhydride for each mole of remaining amino groups bearing exchangeable hydrogens
Implementation Method 3
with the proviso that during or after the second step the reaction mass is heated (cured) at temperature ranging from 130 to 200° C. until at least 30 by weight (wt %) of the emulsion stabilizing agent has a molecular weight higher than 1700 Da
Data Source
AI summary
The present invention relates to emulsion stabilizing agents, to subterranean treatments fluids comprising said emulsion stabilizing agents and to a method of treating subterranean formations using said subterranean treatments fluids.These emulsion stabilizing agents, besides having excellent emulsifying properties, do not cause the swelling and dispersion of clays and are able to provide subterranean treatments fluids with excellent rheological behaviour even at high temperatures.