Water-in-Oil Emulsion for OBM Sludge Removal
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Solution Overview
Problem
The oil-based mud (OBM) sludge deposited in wellbores during drilling forms impermeable filter cakes that resist fracturing operations, hindering the effectiveness of hydraulic fracturing by preventing the passage of fracturing fluids.
Innovation Solution
A water-in-oil emulsion composition is introduced into the wellbore, comprising an organic phase with an organic solvent, emulsifier, and wetting agent, and an aqueous phase with a chelating agent at high pH, which penetrates and dissolves the OBM sludge, removing up to 90% of the filter cake to facilitate fracture initiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If oil-based mud sludge is deposited in the wellbore during drilling, then wellbore stability is maintained, but filter cake formation occurs that resists fracturing operations
Solution Approach 1:
The patent applies parameter changes by using a chelating agent that alters the chemical parameters of the barite particles in the filter cake. The chelating agent changes the solubility characteristics of barite, enabling it to dissolve in the treatment fluid. This chemical parameter change allows the filter cake to be removed without compromising wellbore stability, as the treatment is applied after drilling is complete.
Solution Approach 2:
The patent uses an intermediary substance - a chelating agent - that mediates between the insoluble barite filter cake and the fracturing operation. The chelating agent acts as a chemical intermediary that binds to barite particles, making them soluble and removable. This intermediary enables the transition from a state where filter cake resists fracturing to a state where the formation can be successfully fractured.
2Ease of operation
If conventional acid solutions are used to remove filter cake, then some cleaning effect is achieved, but the filter cake remains highly insoluble and resists removal
Solution Approach 1:
The patent fundamentally changes the chemical parameter approach by using a chelating agent instead of conventional acids. The chelating agent works through a different chemical mechanism - forming soluble complexes with barite ions - which changes the solubility parameters of the filter cake materials. This parameter change enables effective removal of barite particles that are resistant to conventional acid treatments.
Solution Approach 2:
The patent substitutes the mechanical/chemical action of conventional acid dissolution with a chelation-based removal mechanism. Instead of relying on acid-rock dissolution reactions that are ineffective against barite, the system uses chelating agents that selectively bind to barite ions and form soluble complexes. This mechanism substitution enables effective filter cake removal where conventional methods fail.
3Productivity
If multiple treatment stages are used to remove sludge, then removal efficiency increases, but treatment complexity and chemical volumes increase
Solution Approach 1:
The patent merges multiple treatment functions into a single treatment fluid composition. The composition combines a chelating agent, surfactants, and other additives into one integrated formulation that can remove both organic sludge components and inorganic barite particles simultaneously. This merging eliminates the need for multiple sequential treatment stages, reducing process complexity while maintaining high removal efficiency.
Solution Approach 2:
The treatment fluid composition is designed with multi-functionality, serving as both a cleaning agent for organic sludge and a chelating agent for barite removal. The universal composition can handle different types of contaminants (organic and inorganic) in a single application, eliminating the need for specialized treatments for different sludge components and simplifying the overall treatment process.
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 composition effectively removes OBM sludge and filter cake, enhancing injectivity and ensuring successful fracturing operations by dissolving barite particles, thereby improving hydraulic fracturing effectiveness and reducing chemical volumes and treatment costs.
Implementation Method 1
The aqueous phase may include water and a chelating agent... allowing the composition to penetrate the oil-based mud sludge or filter cake having barite... thereby allowing the composition to remove up to 40 wt % of the oil-based mud sludge or filter cake having barite
Implementation Method 2
The organic phase may include an organic solvent, an emulsifier, and a wetting agent
Data Source
AI summary
Provided is a composition that may include a fluid formulation that is a water-in-oil emulsion, having an organic phase and an aqueous phase, the aqueous phase dispersed in the organic phase. The organic phase may include an organic solvent, an emulsifier, and a wetting agent. The aqueous phase may include water, a chelating agent, and a base. Further provided is a method that may include introducing the composition into a wellbore as a single stage treatment, maintaining the wellbore by shutting-in the well, and hydraulic fracturing the wellbore.