Double Emulsified Acids for Deep Wellbore Penetration
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Solution Overview
Problem
Conventional acids used in wellbore stimulation react too quickly with carbonate formations, limiting their ability to penetrate and enhance wellbore productivity, and existing acid formulations are too viscous for efficient pumping in high temperature and high pressure environments.
Innovation Solution
Development of double emulsified acids with a continuous aqueous phase and a non-continuous invert emulsion phase, stabilized by emulsifying agents with specific hydrophilic-lipophilic balances, which slow the acid reaction rate and reduce viscosity, allowing deeper penetration and efficient pumping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional acids are used in carbonate formations, then the acid reacts quickly with the formation, but the penetration depth is limited to only a few inches
Solution Approach 1:
The acid system is segmented into discrete droplets dispersed in a carrier fluid, creating an emulsion system where acid is distributed as many small individual reaction sites rather than a continuous phase, controlling the reaction progression
Solution Approach 2:
An emulsifier acts as an intermediary substance that stabilizes the acid droplets in the carrier fluid, allowing the acid to be transported through the formation without immediate uncontrolled reaction while maintaining droplet integrity during pumping and injection
2Length of moving object
If single emulsified acids are used to slow reaction rate, then penetration depth improves, but viscosity increases making pumping inefficient
Solution Approach 1:
The physical parameters of the acid system are changed by dispersing acid in droplet form within a carrier fluid, fundamentally altering the rheological properties from high viscosity emulsion to low viscosity dispersed system that can be pumped efficiently at high rates
Solution Approach 2:
The system combines acid, carrier fluid, and emulsifier into a composite emulsion system where each component contributes specific properties: acid provides reactivity, carrier fluid provides low viscosity and pumpability, and emulsifier provides stability, achieving both deep penetration and efficient pumping
3Length of moving object
If single emulsified acids are used to retard reaction, then some penetration improvement occurs, but the formulation cannot handle extreme pressures above 10,000 psi
Solution Approach 1:
The system parameters are optimized for HTHP conditions by selecting carrier fluid and emulsifier components that maintain emulsion stability and prevent acid droplet coalescence under extreme pressures and temperatures, ensuring reliable performance in challenging reservoir environments
Data Source
AI summary
Embodiments of the present disclosure are directed to double emulsified acids, specifically water in oil in water (W/O/W) double emulsions with an acidic interior water phase. The double emulsified acid may include two or more emulsifying agents. In addition to improving the stability of the emulsions, the emulsifying agents may help slow the acid reaction rate. The first emulsifying agent may have an HLB greater than 7 and the second emulsifying agent may have an HLB less than or equal to 7. Other embodiments are directed to methods for producing a double emulsified acid and methods for acidizing a carbonate formation including a double emulsified acid.