Directional Wormhole Formation in Subsurface Formations
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Solution Overview
Problem
Current well stimulation techniques, such as matrix acidizing, are limited in extending wormholes beyond the near-wellbore region due to acid diffusivity and radial flow, and lack control over the direction of channel growth in subsurface formations.
Innovation Solution
A method involving determining the lithology and pressure regime of a subsurface formation, injecting a formation-dissolving fluid at a controlled flux rate to create extended wormholes along a defined plane, and using guard wells to create artificial pressure boundaries that guide the fluid flow, allowing wormholes to extend significantly beyond the near-wellbore region in a controlled direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If matrix acidizing is used to dissolve rock matrix and create flow paths, then near-wellbore permeability is improved, but wormhole penetration is limited to within a few feet from the wellbore
Solution Approach 1:
The patent employs cyclic injection and production operations where acid is injected during injection cycles and produced during production cycles. This periodic action allows the acid to penetrate deeper into the formation over multiple cycles, accumulating wormhole length beyond the single-pass limitation while maintaining near-wellbore permeability improvement
Solution Approach 2:
The patent uses perforation operations before acid injection to create initial pathways and reduce skin damage. This preliminary action prepares the formation by removing near-wellbore damage and creating entry points, enabling subsequent acid to penetrate deeper and form longer wormholes than would be possible with intact wellbores
2Productivity
If hydraulic fracturing is conducted to create fractures in tight formations, then flow capacity is substantially increased, but the direction of fracture propagation cannot be controlled
Solution Approach 1:
The patent applies different treatments to different zones by using selective perforation orientations and staged acid injection. By creating preferential flow paths in specific directions through targeted perforations and using diversion agents, the acid preferentially dissolves rock in desired directions, achieving directional control while maintaining the flow capacity enhancement of fracturing
Solution Approach 2:
The patent uses diversion agents and proppant materials as intermediaries to control acid flow direction. These materials are injected to redirect the acid toward target zones, acting as mediators that guide the dissolution process in desired directions while still achieving substantial flow capacity increase through fracture-like pathways
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 method enables the formation of wormholes exceeding 100 feet in length, significantly improving hydrocarbon recovery by altering the pressure field and controlling the direction of wormhole growth, thereby overcoming the limitations of traditional stimulation techniques.
Implementation Method 1
a chemical capable of dissolving the rock matrix forming the hydrocarbon-bearing formation is injected through the well
Implementation Method 2
injecting a formation-dissolving fluid into the subsurface formation at a flux rate that creates wormholes through the rock matrix
Data Source
AI summary
A method for forming extended wormholes in a subsurface formation comprising locating producer wells, injection wells, and guard wells in a field; determining a flux rate for a formation-dissolving fluid such as an acid, the flux rate being dependent upon different variables including the composition of the rock matrix making up the subsurface formation and the type of acid selected; injecting a guard fluid into the subsurface formation, through at least one guard well to form designed pressure boundaries and injecting the acid into the formation at a rate to reach the determined flux rate and thereby forming an extended network of wormholes through the subsurface formation in a defined direction or plane, with or without guard wells.