Patent EA-002587-B1 (EA)
Title: Deliberate fluid removal by capillary imbition
Inventor: HINKEL JERALD J
IPC: E21B43/26
Filed: 2000-04-20
Abstract: 1. A method of removing an initially resident wetting fluid from a fracture contiguous to a geologic formation in a subsurface environment, said method comprising the steps of: creating or enhancing a capillary pressure gradient at an interface, said interface defined by said fracture on one side and said contiguous formation on another side; said capillary pressure gradient being created by injecting a non-wetting fluid, into the formation opposite said fracture; and allowing said initially resident wetting fluid to flow along said gradient, through said interface, from said fracture into said formation. 2. The method of Claim 1 wherein said capillary pressure gradient is created by: injecting into said formation, a non-wetting fluid, said non-wetting fluid creating a fracture in said formation thereafter migrating to said formation opposite said fracture; and injecting into said fracture, a wetting fluid at least partially immiscible with said non-wetting fluid, said wetting fluid initially resident in said fracture opposite said formation. 3. A method for stimulating hydrocarbon production in a water-wet subterranean formation by creating or extending a fracture in said formation, comprising the steps of: injecting a non-wetting fluid into a subsurface formation, from a well in fluid engagement with said formation and a well surface; allowing said non-wetting fluid to leak off from said fracture into said formation; injecting an aqueous-based proppant-containing slurry from said well into said fracture, said slurry initially resident in said fracture; and allowing said slurry to migrate from said fracture into said formation. 4. The method of any of Claims 1-3 wherein said non-wetting fluid is selected from the group consisting of gelled diesel oil, gelled lease oil, gelled kerosene, gelled crude oil, carbon dioxide, and nitrogen to which a surfactant has been added.. 5. The method of any of Claims 1-4 wherein said wetting fluid is comprised of a surfactant or a polymer selected from the group consisting of guar, hydroxypropyl guar, carboxymethyl guar, carboxymethylhydroxypropyl guar, hydroxyethyl cellulose, carboxymethylhydroxyethyl cellulose, hydroxypropyl cellulose, and xanthan and synthetic and cross-linked polymers. 6. The method of any of Claims 1-5 wherein said wetting fluid contains a breaker to degrade said polymer. 7. The method of any of Claims 1-6 wherein said wetting and non-wetting fluids are at least immiscible fluids in contact with one another. 8. The method of any of Claims 1 7 wherein said wetting fluid is injected in a plurality of stages, each stage characterized by a different total volume and/or a different proppant concentration or proppant type. 9. The method of any of Claims 1 8 wherein said formation is a water-wet formation. 10. The method of any of Claims 1-9 wherein said formation is an oil-wet formation, and further comprising a first step of injecting into said formation, material to substantially reverse the wetting characteristics of a portion of said formation contiguous to said fracture. 11. The method of Claim 10 wherein said material is selected from the group comprising surfactant, an oxidizer and a mixture thereof.