Encapsulated Thermochemical Drilling Fluid for Barite Filter Cake Removal
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Solution Overview
Problem
Existing drilling fluids form impermeable filter cakes that block hydrocarbon production and cause formation damage, particularly in permeable formations, and conventional removal methods like acids and enzymes are costly or ineffective.
Innovation Solution
Incorporation of encapsulated thermochemical compounds, such as ammonium chloride and sodium nitrite, in drilling fluids that react to generate heat and nitrogen gas, effectively removing the filter cake through exothermic reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If barite is used as weighting material to increase hydrostatic pressure, then drilling fluid's ability to control formation pressure is improved, but filter cake becomes impermeable and causes formation damage
Solution Approach 1:
The patent converts the harmful impermeable filter cake into a beneficial temporary barrier by using encapsulated thermochemical compounds that react to generate heat and nitrogen gas. The filter cake is deliberately formed to block hydrocarbons during drilling, then destroyed in situ using the thermochemical reaction products to restore formation permeability and prevent damage.
Solution Approach 2:
The patent changes the physical and chemical parameters of the filter cake by introducing encapsulated thermochemical compounds (ammonium chloride and sodium nitrite) that undergo exothermic reaction. The reaction alters temperature, pressure, and chemical composition parameters to transform the filter cake from a stable impermeable barrier into a destroyed porous structure.
2Object-affected harmful factors
If conventional removal methods like acids and enzymes are used, then filter cake removal is attempted, but cost increases and effectiveness decreases
Solution Approach 1:
The patent implements self-service by incorporating the removal agents (ammonium chloride and sodium nitrite) directly into the drilling fluid formulation. The system uses itself to remove the harmful filter cake through in situ thermochemical reaction, eliminating the need for separate acid or enzyme treatments and reducing overall cost.
Solution Approach 2:
The patent applies preliminary action by pre-encapsulating the thermochemical compounds (ammonium chloride and sodium nitrite) within the drilling fluid before drilling operations. This ensures the removal agents are already in position and activated when needed, avoiding the need for subsequent costly and complex removal operations.
3Object-affected harmful factors
If encapsulated thermochemical compounds are added to drilling fluid, then filter cake removal effectiveness is improved, but drilling fluid composition complexity increases
Solution Approach 1:
The patent applies nesting by encapsulating two chemical compounds (ammonium chloride and sodium nitrite) within a single polymer microcapsule structure. This nested arrangement allows multiple functional components to be integrated into one unit, simplifying the overall fluid composition while maintaining the thermochemical reaction capability for filter cake removal.
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 encapsulated thermochemicals efficiently reduce or eliminate filter cake, enhancing hydrocarbon production by maintaining wellbore integrity and reducing formation damage, while maintaining the drilling fluid's properties.
Implementation Method 1
the reaction of the encapsulated thermochemical compounds generates heat and nitrogen gas
Implementation Method 2
allowing the drilling fluid composition to reach a temperature in the wellbore sufficient for the encapsulated thermochemical compounds to react
Data Source
AI summary
Drilling fluid compositions may include a weighting agent, a nitrite-containing compound, and an ammonium-containing compound, where the nitrite-containing compound and the ammonium-containing compound may be encapsulated together in copolymer micro-particles forming encapsulated thermochemical compounds, and where at least one property selected from the group consisting of the density, the plastic viscosity, the yield point, the gel strength, and the pH, of the drilling fluid composition may be substantially similar to the at least one property of a comparable drilling fluid composition devoid of the encapsulated thermochemical compounds. Methods for reducing a filter cake from a wellbore surface in a subterranean formation are also provided. The methods may include introducing into the wellbore the drilling fluid compositions, allowing the drilling fluid composition to reach a temperature in the wellbore sufficient for the encapsulated thermochemical compounds to react, where the reaction of the encapsulated thermochemical compounds generates heat and nitrogen gas.