Elan Energy Inc.

Alberta Oil Sands Technology and Research

Ben I Nzekwu

Kenneth E Kisman

Peter J Pelensky

Peter D Sametz

Edmund C Lau

Disclosed is a gravity-drainage assisted steam flooding process for the recovery of all from thin viscous heavy oil reservoirs using a single horizontal wellbore. Steam is injected through a fully or partially insulated tubing to exit at or near the toe of a long horizontal well penetrating a viscous oil reservoir. Initially, low (10-30%) quality steam is circulated along the well to condition the wellbore and increase the heated radius to about 1 or 2 meters. Oil and reservoir fluids immediately adjacent to the wellbore are produced through the annular space between the insulated tubing string and a slotted liner that surrounds it. After the period of low quality steam circulation, the production outlet is shut in or constrained and steam injection is continued to initiate an active steam chamber zone along a portion of the wellbore. Subsequently, fluid withdrawal is resumed at the production outlet, while the annular liquid level in the vertical section is controlled to maintain a nearly constant pressure at the production outlet. The injection of a higher (50-70% or more) quality steam is continued at a rate similar to or higher than the initial rate to cause the expansion and propagation of the active steam heated volume vertically towards the top of the formation, longitudinally along the horizontal well from the toe towards its heel, and laterally away from the well towards the inter-well boundary with the next row of horizontal well. As steam flows into the reservoir under both gravitational counter current flow and pressure drive, the oil, steam condensate and reservoir fluids heated both conductively and convectively drain towards the slotted liner annulus of the horizontal wellbore and is then pumped to the surface.

Single horizontal wellbore gravity drainage assisted steam flooding

An in-situ combustion method is provided for the recovery of viscous oil from an oil-bearing reservoir. A linear array of vertical air injection wells is drilled into the reservoir; the wells are completed in the upper portion of the reservoir. One or more gas production wells are provided, remote from the row of injection wells, said gas production wells also being completed in the upper portion of the reservoir. A horizontal oil production well is completed in the bottom portion of the reservoir, aligned with and positioned in spaced relation beneath the vertical injection wells. The reservoir is prepared for ignition and combustion is initiated at each of the injection wells. A hot fluid-transmissive chamber is formed around each of the injection wells as combustion proceeds. Combustion gas communication is established with the gas production wells. Heated oil and water, produced by the combustion front in each hot chamber, drains under the effect of gravity and is produced from the horizontal production well. The main features of the process are the implementation of gravity drainage to a basal horizontal well in a combustion process and the splitting of liquid and gas production.

Growing community of inventors

Calgary, Canada

Ben I Nzekwu