Browse Prior Art Database

Recovery-Aid Conformance Enhancement (R-ACE) in Bitumen Recovery Processes

IP.com Disclosure Number: IPCOM000247176D
Publication Date: 2016-Aug-11
Document File: 7 page(s) / 241K

Publishing Venue

The IP.com Prior Art Database

Abstract

This disclosure describes a means for addressing reservoir conformance challenges in heavy oil gravity drainage recovery methods, providing a method to deplete the bypassed oil between horizontal wells or well pairs. The method improves the mobility and sweep / recovery of the bypassed oil by providing heat and dilution to the typically bypassed oil during regular operation. Heat and dilution are provided either through a HZ well pair or a single HZ well, termed conformance-enhancing well system (CEWS). A CEWS is drilled and operated before or at the same time or within a few years of the starting injection and production from the main HZ well pair. The CEWS is operated in either a cyclic or continuous mode. The method increases bitumen recovery factor and also reduces life cycle steam to oil ratio.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 16% of the total text.

Page 01 of 7

Title: Recovery-Aid Conformance Enhancement (R-ACE) in Bitumen Recovery Processes

Abstract:

This disclosure describes a means for addressing reservoir conformance challenges in heavy oil gravity drainage recovery methods, providing a method to deplete the bypassed oil between horizontal wells or well pairs. The method improves the mobility and sweep / recovery of the bypassed oil by providing heat and dilution to the typically bypassed oil during regular operation. Heat and dilution are provided either through a HZ well pair or a single HZ well, termed conformance-enhancing well system (CEWS). A CEWS is drilled and operated before or at the same time or within a few years of the starting injection and production from the main HZ well pair. The CEWS is operated in either a cyclic or continuous mode. The method increases bitumen recovery factor and also reduces life cycle steam to oil ratio.

1



Page 02 of 7

Problem:

Bitumen recovery processes, such as SAGD, SA-SAGD (also known as ES-SAGD), N-Solv, and Heated VAPEX, suffer from conformance problem. The problem arises from the recovery-aid agent's (steam and/or diluent vapour) propensity to rise to the top of the reservoir, creating, between two adjacent oil-depleted chambers a "hill of bypassed oil" that is narrower at the top and wider at the bottom. The current practice is to let the "bypassed oil" region develop for 10 to 20 years and then drill an infill well in that region. This delays production and adds complexity related to drilling an infill in a heated reservoir. There is a need to enhance conformance in the afore-mentioned recovery processes.

Invention:

R-ACE is a
recovery-aid
conformance
enhancement
method, which is
based on the
concept that
lateral
conformance can
be improved if the
immobile oil
ahead of an oil-
depleted
recovery-aid chamber is made more mobile. Higher mobility of oil, ahead of the said chamber in SAGD, SA-SAGD (or ES-SAGD), N-Solv, or Heated VAPEX of well system 1 (WS1), is achieved, in the invention, by providing heating and dilution through well system 2 (WS2), as shown in Fig. 1. The oil mobilization allows the recovery-aid chamber of WS1 expand sideways into the region that would have been bypassed in prior art. WS2, which allows bitumen to be mobile ahead of the said chamber belonging to the main well system (WS 1), is called a conformance-enhancing well system (CEWS). The CEWS may be a horizontal (HZ) injection-production well pair like WS2 in Fig. 1, or a single HZ well that may act as an injector or a producer during its cyclical operation.

An important aspect of R-ACE is to provide a recovery-aid agent in CEWS that is richer in diluent in a diluent-steam mixture than that in WS1. WS1 and CEWS are spaced and operated such that the time to reach a temp. of 40 - 70 °C at the mid-point between them is less than or equal to the time for the recovery-aid chamber to reach the top of the reservoir. This should allow the "hill of oil" in Fig.1 to be mobile, and pro...