Microemulsion Fluids for Oil-Based Mud Removal in Subterranean Formations
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Solution Overview
Problem
Formation damage in subterranean reservoirs caused by hydrocarbon and synthetic oil-based muds leads to reduced hydrocarbon production, as these materials deposit and invade the reservoir, altering pore volume and permeability, and existing methods are inadequate for complete removal without causing further damage.
Innovation Solution
The use of microemulsions and in situ-formed fluids with high-density brines, comprising surfactants, linkers, and acids, to solubilize and remove non-polar materials such as oil-based mud filter cakes, reversing wettability from oil-wet to water-wet and minimizing formation damage, allowing for effective clean-up without circulating the well.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional drilling fluids are used, then drilling operations can be performed, but formation damage occurs due to deposition and invasion of non-polar materials
Solution Approach 1:
The patent uses microemulsions as intermediary substances that contain both polar and non-polar phases. These microemulsions act as mediators between the aqueous drilling fluid system and the non-polar oil-based mud components, allowing the drilling fluid to maintain its functionality while reducing formation damage through controlled solubilization of harmful materials.
Solution Approach 2:
The patent changes the physical and chemical parameters of the drilling fluid by incorporating microemulsions with specific surfactant concentrations, oil phase ratios, and salinity levels. These parameter changes enable the drilling fluid to transition from causing formation damage to actively cleaning and protecting the formation while maintaining drilling operational capabilities.
2Productivity
If existing clean-up methods are used, then some non-polar materials can be removed, but complete removal is not achieved and further damage may occur
Solution Approach 1:
The patent employs composite microemulsion systems combining multiple surfactants (ionic and nonionic), co-solvents, and polar/non-polar phase combinations. This composite approach creates a synergistic cleaning mechanism that achieves complete removal of non-polar materials without causing formation damage, overcoming the limitations of single-component clean-up methods.
Solution Approach 2:
The patent utilizes dynamic microemulsion systems that can adapt their structure and composition in response to different contamination levels and formation conditions. The microemulsions dynamically adjust their solubilization capacity and interfacial properties to optimize clean-up effectiveness while preventing further formation damage.
3Productivity
If high-density brines are used in microemulsions, then non-polar materials are effectively solubilized and removed, but the complexity of fluid formulation increases
Solution Approach 1:
The patent develops universal microemulsion formulations with high-density brines that serve multiple functions simultaneously: weight control, non-polar material solubilization, formation protection, and clean-up enhancement. This multi-functionality reduces the need for separate specialized fluids, thereby managing formulation complexity while maintaining high removal efficiency.
Solution Approach 2:
The patent applies local quality optimization by adjusting microemulsion composition and density specifically in zones where non-polar material removal is most critical. The high-density brine microemulsions are targeted toward areas with heavy oil-based mud invasion, concentrating the complex formulation where it provides maximum benefit while simplifying overall fluid deployment.
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 significantly reduces formation damage, enhances hydrocarbon recovery, and increases water injection rates by effectively incorporating and removing non-polar materials, including oil-based muds and synthetic oil-based muds, without additional oil or solvent requirements, facilitating easier well stimulation and enhanced oil recovery.
Implementation Method 1
incorporating at least part of the non-polar material into an incorporating fluid selected from the group consisting of (1) the mesophase surfactant solution and/or the micellar solution, (2) the SPME
Implementation Method 2
rock wettability alteration by fluids pumped downhole
Data Source
AI summary
Mesophase surfactant solutions and/or micellar solutions, pre-formed single phase microemulsions (SPMEs), and in situ-formed fluids may be used to clean up and remove hydrocarbons and synthetic oils such as oil-based mud filter cake and near wellbore damage in oil and gas wells. Removal occurs by solubilization of the hydrocarbons and synthetic oils into the micellar solutions, SPME, in situ-formed fluids, etc. when the fluid formulation contacts the hydrocarbons and synthetic oils. An in situ-formed fluid (e.g. microemulsion), may be formed when one or more surfactant, an optional linker, optional co-surfactant, optional acid, optional co-solvent and a polar high-density brine phase, and eventually some amount of organic phase, contacts the subterranean location and solubilizes the hydrocarbons and synthetic oils encountered, such as in the near wellbore of a subterranean formation. The micellar solutions, microemulsions, in situ-formed fluids, etc. are effective for removing the formation damage caused by hydrocarbons and synthetic oils.