Method and System For Enhancing A Recovery Process Employing One or More Horizontal Wellbores

Abstract

The present invention relates generally to a system and method for enhancing a recovery process employing one or more substantially horizontal wellbores. More particularly, the present invention relates to a method and system for enhancing a recovery process employing one or more horizontal wellbores by providing a zone of increased permeability in a hydrocarbon reservoir to facilitate vertical movement of flowable materials through the reservoir to thereby enhance the recovery process. In some embodiments, the reservoir comprises one or more vertical permeability impediments.

Description

CROSS-REFERENCE TO RELATED APPLICATIONThis application claims priority from Canadian Patent Application 2,651,527 filed Jan. 29, 2009 entitled METHOD AND SYSTEM FOR ENHANCING A RECOVERY PROCESS EMPLOYING ONE OR MORE HORIZONTAL WELLBORES, the entirety of which is incorporated by reference herein.FIELD OF THE INVENTIONThe present invention relates generally to a system and method for enhancing a hydrocarbon recovery process. More particularly, the present invention relates to a system and method for enhancing a recovery process employing one or more horizontal wellbores by selectively altering vertical permeability in a reservoir.BACKGROUND OF THE INVENTIONOil and gas are nonrenewable natural resources relied upon heavily in the industrialized world. The rising demand for oil and gas, combined with declining conventional resources, has necessitated the development of alternative sources of oil, as well as methods of enhancing recovery from both conventional and alternative resources.T...

AI Technical Summary

Benefits of technology

In another aspect, there is provided method of increasing permeability of at least one vertical permeability impediment in a reservoir to enhance a hydrocarbon recovery process employing one or more horizontal wellbores. The method comprises providing at least one accessory conduit in the reservoir in a region substantially above or below the one or more horizontal wellbores. The conduit has one or more portions that extend through the at least one vertical permeability impediment to facilitate movement of flowable material therethrough to enhance the recovery process.

In another aspect, there is provided a method of enhancing a hydrocarbon recovery process employing one or more horizontal wellbores in a reservoir having at least one vertical permeability impediment. The method comprises increasing the effective permeability of the at least one vertical permeability impediment in a region substantially above or below the one or more horizontal wellbores to facilitate the movement of flowable materials through the at least one vertical permeability impediment to enhance the recovery process.

In another aspect, there is provided a method of enhancing recovery process performance in a hydrocarbon reservoir having at least one vertical permeability impediment. The method comprises providing a first wellbore having a substantially horizontal portion for collection of hydrocarbons. The method further comprises providing at least one accessory conduit extending through the reservoir in a region substantially above or below the first wellbore. The accessory conduit has one or more portions that extend through the vertical permeability impediment to facilitate movement of flowable materials therethrough to enhance recovery.

In another aspect, there is provided an in situ heavy oil recovery process for recovering hydrocarbons from a reservoir having one or more vertical permeability impediments. The method comprised providing one or more horizontal wellbores in the reservoir, including a production wellbore, and increasing the effective permeability of the one or more vertical permeability impediments above the production wellbore in a region extending along at least a portion of the length of the production wellbore to facilitate the movement of flowable materials through the one or more vertical permeability impediments and toward the production wellbore.

In yet another aspect, there is provided a system for recovering hydrocarbons from a reservoir. The system comprises one or more substantially horizontal wellbores, including a production wellbore, and at least one accessory conduit located substantially above or below the one or more substantially horizontal wellbores for enhancing movement of flowable materials through the reservoir to thereby enhance recovery. In some embodiments, the reservoir has at least one vertical permeability impediment and the accessory conduit has one or more portions that extend through the at least one vertical permeability impediment to facilitate movement of flowable materials therethrough.

Problems solved by technology

In-situ heavy oil recovery methods are typically applied when a deposit cannot be mined economically due to the depth of overburden.

A key challenge with the practical application of any recovery process utilizing one or more horizontal wellbores, or otherwise relying on vertical movement of flowable material through a reservoir, is that permeability in most reservoirs is not homogeneous.

While the permeability of oil sand may generally be in the range of a few darcies to a few hundred darcies, the vertical permeability of an oil sands reservoir is frequently disrupted by layers of material having substantially reduced permeability.

These layers or matrices can form vertical permeability impediments that inhibit or prevent the vertical flow of materials through the reservoir, relative to the more permeable pay zones, and thus limit production rate and resource recovery.

However, each suffer from disadvantages that will be apparent to persons skilled in the art.

However, attempts to propagate fractures through compartmentalized or stratified formations have historically yielded unpredictable and poor results, such as insufficient fracture extension and inadequate propping of fractures adjacent to less permeable areas of the formation.

Such a system is not designed for gravity drainage and is not suited for reservoirs where fracture extension occurs in a horizontal versus a vertical orientation.

Moreover, a thick or substantially impermeable impediment, such as shale, may not be effectively propped open.

Such a system for increasing vertical permeability in a reservoir is costly and inefficient.

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