Amine Surfactant Invert Emulsion for Wellbore Cleanup
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Solution Overview
Problem
The use of aqueous acid solutions to invert water-in-oil emulsion drilling fluids for oil production leads to aqueous acid solution-crude oil emulsions and sludging, which increases viscosity and complicates cleanup, potentially damaging oil-producing zones and incurring additional costs and risks.
Innovation Solution
A method involving a reversible invert emulsion with an amine surfactant that protonates upon contact with indigenous formation fluids, creating an oil-in-water emulsion with low viscosity, reducing the need for external acids and minimizing emulsion-related issues, using a fluid composition with an aqueous fluid dispersed as a discontinuous phase within an oleaginous fluid, where at least 40 vol % of non-proppant solids are water-soluble at acidic pH.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If an aqueous acid solution is used to invert the water-in-oil emulsion drilling fluid, then the emulsion inverts to an oil-in-water emulsion which water wets the producing formations, but aqueous acid solution-crude oil emulsions and crude oil sludging are produced, increasing viscosity and complicating cleanup
Solution Approach 1:
The patent uses an anionic sulfonate surfactant as an intermediary substance added to the aqueous acid solution. This surfactant mediates between the acid solution and crude oil, preventing harmful emulsion formation and sludging while allowing the desired emulsion inversion to occur. The surfactant acts as a bridge that enables the inversion process without the negative side effects.
Solution Approach 2:
The patent changes the chemical composition parameters of the aqueous acid solution by adding specific concentrations of anionic sulfonate surfactants (0.1-10% by weight). This parameter change transforms the acid solution from one that causes sludging to one that enables clean inversion, modifying the interfacial properties to prevent harmful emulsion formation.
2Object-generated harmful factors
If anionic sulfonate surfactants are added to the acid solution to prevent emulsion formation, then aqueous acid solution-crude oil emulsions are prevented, but the surfactants may react with the amine emulsifier after protonation, preventing water solubility and emulsion inversion
Solution Approach 1:
The patent optimizes the concentration parameters of both the anionic sulfonate surfactant (0.1-10% by weight) and the amine emulsifier (0.5-5% by weight) to achieve the desired effect. By carefully controlling these parameters, the system prevents harmful emulsions while maintaining sufficient free amine groups for protonation and inversion, balancing two competing requirements through quantitative optimization.
Solution Approach 2:
The patent uses a controlled amount of anionic sulfonate surfactant (partial action) rather than excessive amounts that would guarantee prevention but risk over-reaction with the amine emulsifier. The surfactant concentration is optimized to be sufficient for preventing sludging but limited enough to avoid complete consumption of the amine emulsifier, maintaining the inversion capability.
3Ease of operation
If external aqueous acid solution is pumped into the wellbore to invert the emulsion, then the water-in-oil emulsion inverts to an oil-in-water emulsion, but additional cost and risk are incurred in the process
Solution Approach 1:
The patent modifies the drilling fluid composition itself to contain the necessary anionic sulfonate surfactants and amine emulsifiers, enabling the system to perform the inversion function using its own components rather than requiring external acid solution injection. The drilling fluid serves its own inversion needs, eliminating the need for separate acid treatment operations.
4Stability of the object's composition
If the emulsion viscosity is increased to maintain stability, then the emulsion remains stable during drilling, but the inverted emulsion becomes highly viscous and difficult to remove, potentially damaging crude oil producing zones
Solution Approach 1:
The patent changes the compositional parameters of the inverted emulsion by ensuring adequate surfactant concentration and using water-soluble solids that dissolve in the aqueous continuous phase. These parameter changes prevent the formation of highly viscous inverted emulsions, maintaining fluidity and ease of removal while preserving stability during the drilling operation.
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
This approach facilitates efficient oil production by reducing viscosity, preventing emulsion-related damage, and minimizing operational costs by utilizing indigenous formation fluids for emulsion inversion, thereby simplifying cleanup and reducing the risk of damage to oil-producing zones.
Implementation Method 1
contacting the second fluid with an indigenous formation fluid for a period of time sufficient to produce a third fluid from at least a portion of the second fluid, wherein the amine surfactant is selected such that contacting the second fluid with the indigenous formation fluid for the sufficient period of time protonates at least a portion of the amine surfactant in the second fluid
Implementation Method 2
a reversible invert emulsion comprising an aqueous fluid dispersed as a discontinuous phase within an oleaginous fluid
Data Source
AI summary
Disclosed herein is a method comprising displacing a first oil-based fluid present in an open hole interval of a wellbore with a second fluid; and contacting the second fluid with an acidic indigenous formation fluid to produce a third fluid wherein the second fluid an aqueous fluid dispersed as a discontinuous phase within an oleaginous fluid, and an amine surfactant, wherein the amine surfactant is selected such that contacting the second fluid with indigenous fluid protonates at least a portion of the amine surfactant in the second fluid to produce the third fluid comprising an emulsion comprising the oleaginous fluid reversibly dispersed as a discontinuous phase within the aqueous fluid. A system for treating a subterranean well and a fluid are also disclosed.