Self-Destructive Barite Filter Cake for Formation Damage Reduction
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Solution Overview
Problem
Existing drilling fluids, particularly those containing barite, form impermeable filter cakes that block reservoir productivity and cause formation damage, making their removal challenging and costly, especially in horizontal wells.
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 in drilling fluids, then hydrostatic pressure and wellbore stability are improved, but filter cake formation causes formation damage and reservoir productivity loss
Solution Approach 1:
The patent converts the harmful filter cake formed by barite into a beneficial self-destructing structure by incorporating encapsulated thermochemical compounds. The filter cake initially provides necessary hydrostatic pressure and wellbore stability, then automatically destroys itself through thermochemical reaction when it contacts the formation, transforming the harmful impermeable barrier into a self-destructing mechanism that eliminates formation damage while maintaining the necessary pressure control function.
Solution Approach 2:
The patent changes the physical and chemical parameters of the drilling fluid system by incorporating encapsulated thermochemical compounds (ammonium chloride and sodium nitrite). These compounds remain stable during drilling operations but undergo rapid thermochemical decomposition when the filter cake contacts the formation, changing the state from stable to reactive and enabling automatic filter cake destruction while maintaining hydrostatic pressure control.
2Productivity
If encapsulated thermochemical compounds are added to drilling fluid, then filter cake removal efficiency is improved, but drilling fluid composition complexity increases
Solution Approach 1:
The patent applies nesting by placing the thermochemical compounds (ammonium chloride and sodium nitrite) inside encapsulated micro-particles within the drilling fluid system. This nested structure allows the compounds to be transported through the drilling fluid without premature reaction, then activates automatically when the filter cake contacts the formation, achieving high filter cake removal efficiency while keeping the base drilling fluid composition relatively simple.
Solution Approach 2:
The encapsulated micro-particles serve as an intermediary carrier that delivers the thermochemical compounds to the filter cake interface. This intermediary mechanism enables the compounds to remain dormant during drilling operations and activate only when needed, simplifying the overall system design while achieving efficient filter cake removal through the mediated thermochemical reaction.
3Object-affected harmful factors
If conventional filter cake removal methods are used, then formation damage is reduced, but operational cost and time increase
Solution Approach 1:
The patent implements self-service by designing a system where the filter cake itself triggers the destruction mechanism through its own presence. When the filter cake contacts the formation, it automatically initiates the thermochemical reaction that destroys itself, eliminating the need for external removal operations. This self-destructing mechanism reduces formation damage while eliminating the time and cost associated with conventional manual or chemical removal methods.
Solution Approach 2:
The patent applies preliminary action by pre-incorporating the encapsulated thermochemical compounds into the drilling fluid before drilling operations begin. These compounds are prepared in advance within the encapsulated micro-particles and remain dormant until activated by contact with the filter cake at the formation interface, enabling automatic filter cake destruction without requiring post-drilling intervention or additional operational time.
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 reservoir productivity by maintaining drilling fluid properties and reducing formation damage, with removal efficiencies up to 99%.
Implementation Method 1
the reaction of the encapsulated thermochemical compounds generates heat and nitrogen gas
Implementation Method 2
the reaction of the encapsulated thermochemical compounds generates heat and nitrogen gas
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.