Polyamide Emulsion Stabilizers for High-Temperature Shale Stability
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Solution Overview
Problem
Existing emulsion stabilizers 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.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional emulsion stabilizing agents (surfactants) are used in oil-based muds, then excellent emulsifying properties are achieved, but shale swelling and dispersion increase leading to wellbore instability
Solution Approach 1:
The patent changes the molecular weight parameter of the polyamide emulsion stabilizing agent to greater than 1700 Da, which fundamentally alters its interaction with shale minerals. This parameter change reduces the agent's ability to cause shale swelling and dispersion while maintaining emulsion stability, directly resolving the technical contradiction between reliable emulsification and harmful shale effects
Solution Approach 2:
The patent creates a composite molecular structure by condensing fatty acids or carboxylic acids with polyamines to form polyamides with specific molecular characteristics. This composite material approach combines the emulsifying properties of polyamides with controlled molecular weight to achieve both excellent emulsion stability and reduced shale reactivity, resolving the contradiction between these two opposing requirements
2Ease of manufacture
If water-based muds are used, then cost effectiveness and environmental friendliness are improved, but wellbore collapse occurs in water-sensitive shale formations
Solution Approach 1:
The patent introduces a specially designed polyamide emulsion stabilizing agent as an intermediary component in oil-based muds. This intermediary substance modifies the fluid's interaction with shale formations, providing the shale inhibition characteristics typically associated with oil-based systems while allowing the use of optimized emulsion formulations that balance cost and environmental considerations with wellbore stability requirements
3Ease of manufacture
If polyamides with lower molecular weight are used, then easier processing and lower cost are achieved, but emulsion stability and high temperature performance deteriorate
Solution Approach 1:
The patent establishes a critical threshold parameter for molecular weight (greater than 1700 Da) that fundamentally changes the polyamide's performance characteristics. This parameter change ensures adequate emulsion stability and high-temperature performance while maintaining reasonable processing characteristics, resolving the contradiction between ease of manufacture and reliability at elevated temperatures
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 provide excellent emulsion stability and rheology, minimizing shale swelling and dispersion, even at high temperatures, thus stabilizing wellbores and maintaining fluid integrity.
Implementation Method 1
reacting i) 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.