Single Phase Microemulsion Drilling Fluid Filter Cake Removal
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Solution Overview
Problem
Current drilling fluids used in oil and gas well drilling often result in wellbore skin damage and filter cake deposition, which can lead to reduced hydrocarbon production and formation damage, particularly when using invert emulsion drilling fluids, as they are difficult to completely remove without causing additional damage.
Innovation Solution
A method involving the conversion of invert emulsion drilling fluids to single phase microemulsions, which allows for the incorporation and removal of filter cake particles without circulating the well, using a composition that includes a surfactant, polar, and nonpolar phases, along with an optional chelating agent like polyamino carboxylic acid to solubilize bridging particles, facilitating efficient filter cake decomposition and removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If invert emulsion drilling fluid is used to drill the wellbore, then the drilling fluid can effectively cool and clean the rotary bit and carry cuttings, but the invert emulsion forms a filter cake that causes wellbore skin damage and reduced hydrocarbon production
Solution Approach 1:
The patent applies parameter changes by altering the chemical composition and phase structure of the drilling fluid. Specifically, it converts the conventional two-phase invert emulsion system into a single-phase microemulsion system by adjusting surfactant concentration, oil-to-water ratio, and adding co-surfactants. This parameter transformation allows the drilling fluid to maintain its drilling performance while eliminating filter cake formation, thereby resolving the contradiction between drilling efficiency and formation damage.
Solution Approach 2:
The patent employs composite materials by creating a microemulsion system that integrates multiple components (surfactants, co-surfactants, oil phase, water phase) into a single homogeneous phase. This composite structure provides the dual benefit of maintaining effective drilling fluid properties (cuttings suspension, bit cooling) while preventing harmful filter cake deposition on the formation, thus resolving the technical contradiction.
2Object-affected harmful factors
If conventional methods are used to remove filter cake, then some filter cake can be removed, but complete removal is difficult and may cause additional formation damage
Solution Approach 1:
The patent applies preliminary action by preventing filter cake formation in the first place through the use of single-phase microemulsion drilling fluid. Since the microemulsion system does not form conventional filter cakes, there is no need for subsequent removal operations that could risk formation damage. This preventive approach ensures both complete filter cake elimination and formation integrity.
Solution Approach 2:
The patent converts the potential harm of emulsion-based drilling fluids (filter cake formation) into a benefit by developing a single-phase microemulsion system. The microemulsion's unique structure allows it to perform all necessary drilling functions while inherently preventing filter cake deposition. This transformation eliminates the need for harmful removal operations and protects formation integrity.
3Ease of operation
If a single phase microemulsion is used to convert and remove invert emulsion, then filter cake particles can be effectively removed without circulating the well, but the composition and formulation become more complex
Solution Approach 1:
The patent applies merging by combining multiple functions into a single drilling fluid system. The single-phase microemulsion simultaneously performs drilling fluid functions (cuttings suspension, bit cooling) and filter cake prevention/removal functions. This consolidation eliminates the need for separate filter cake removal operations and simplifies the overall process despite the sophisticated composition.
Solution Approach 2:
The patent employs universality by designing a single-phase microemulsion drilling fluid that serves multiple purposes: it acts as an effective drilling fluid, prevents filter cake formation, and enables filter cake removal. This multi-functional approach simplifies operations by eliminating the need for separate treatment steps while the complex composition is managed through standardized formulation procedures.
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 effectively reduces formation skin damage and enhances hydrocarbon recovery by allowing for the complete or significant removal of filter cake particles, improving both production and injection rates without causing further formation damage.
Implementation Method 1
The invert emulsion is changed to either a water continuous (oil-in-water) or oil continuous (water-in-oil) microemulsion by adding a single phase microemulsion composition
Implementation Method 2
an optional chelating agent like polyamino carboxylic acid to solubilize bridging particles
Data Source
AI summary
Single phase microemulsions improve the removal of filter cakes formed during drilling with invert emulsions. The single phase microemulsion removes oil and solids from the deposited filter cake. Optionally, an acid capable of solubilizing the filter cake bridging particles may also be used with the microemulsion. In one non-limiting embodiment the acid may be a polyamino carboxylic acid. Skin damage removal from internal and external filter cake deposition can be reduced.