Method for Recovering Hydrocarbons from Subterranean Formations

Abstract

Recovery of viscous hydrocarbon from subterranean formations is assisted by using a plurality of novel U-tube type wells, each with dual wellheads, a moveable wellbore packer, a lateral section with a concentric communication zone and with sequential injection production perforations in which heat is injected into the proximal perforations and hot oil and produced fluids are produced from the distal perforations, the whole process being controlled by modulating the production flow where the wellbore fluids are controlled to act as a hydraulic seal to limit bypass of injected fluids. The injection-production displacement process moves axially along the wellbore in a sequential manner as hydrocarbon volumes are depleted by injected fluid displacement of oil and oil and water production.

Description

CROSS REFERENCE TO RELATED APPLICATIONS [0001] This application claims priority from provisional application 60 / 712,289 filed Aug. 30, 2005 and Disclosure Document 521,535 by Dr. Henry Crichlow.INTRODUCTION [0002] This invention relates generally to a new technology application and a new type of oil well for recovery of viscous hydrocarbons from subterranean oil bearing formations. The technology involves the novel use and application of equipment and techniques in which horizontal wells are drilled from the surface down to and across an oil bearing formation and back up to the surface, in a manner similar to that of drilling under a river crossing when laying pipelines across country. This new type of horizontal well is called a Uniwell™ because it has two surface wellheads one at each end of the axis of the horizontal system. Either wellhead can be used for either injection or production as needed by the operator. [0003] The technology is a new application using some elements of a...

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Benefits of technology

[0102] Another specific objective is to use the slim-hole drilling in the upward portion of the wellbore to minimize damage to near surface water zones on the “punch-out” or exit side of the wellbore since drilling occurs through a small rock volume limiting the potential for surface zone damages.

[0103] Another specific objective is to use the slim-hole drilling in the upward portion of the wellbore to minimize damage to near surface water ...

Problems solved by technology

This technology while theoretically possible is operationally difficult to hit such a small underground target, i.e the axial cross-section of a typical 8-inch wellbore using a horizontal penetrating drill bit.

This type of downhole flange connection is extremely difficult if not impossible to implement in current oilfield practice.

The laboratory demonstration in this patent shows that the annular steam zone is very conductive to oil production and allows premature steam breakthrough.

Based on this demonstrated observation, it is difficult if not impossible, to conceive a situation taught by this patent in which the injected steam as drive fluid will not preferentially flow under the hundreds of pounds injection pressure along the heated annular zone and thus bypassing the cold viscous oil saturated formation.

It is difficult to visualize the steam entering a cold highly viscous formation while a highly open wellbore is available for fluid flow away from the formation.

This situation is not only physically impossible but it thermodynamically impossible for the hot fluid to flow “against the pressure gradient”.

Very few of these prior art systems have been used in the industry with any success because of their technical complexity, operational difficulties, and being physically impossible to implement or being extremely uneconomical systems.

These include; the inability of the method to inject the hot fluid into a cold highly viscous oil in the formation; the inability to overcome the viscosity effect, wherein the viscosity of steam is less than 0.020 cp under the reservoir conditions which makes the flow of steam through porous media 5,000,000 times easier than cold high viscosity oil of 100,000 cp.

This flow ratio is based directly on the viscosity ratios of 100,000/0.02; the inability of the method or process to prevent bypass of injected fluid directly from the injector source towards the producing sink; the inability of the method or process to provide an effective seal to prevent high pressure injected steam from bypassing cold viscous oil impregnated formation and moving directly from the injector source towards the producing sink; the inability of the method or process to form a viable communication zone from the steam zone or chamber to th...

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