A research plan is proposed under which the development of a comprehensive reaction model, as needed for predictive numerical simulation of in-situ combustion, will be extended to include low-temperature oxidation and its products. It is expected that this change will make it possible for the first time to make useful predictions of field behaviour, and especially of combustion front stability, a critical criterion for success in heavy oils.
Primary production in the Lloydminster heavy oil region is declining rapidly, and even many of the waterfloods, where they can be implemented successfully, are approaching maturity. In spite of many field trial and investigations, it is still common to designate 80% or more of this resource in a field as “unrecoverable by proven means.” Although solvent-vapour extraction (SVX) processes, such as Vapex, offer real hope that profitable oil recoveries can be boosted much higher, history has taught us that new methods rarely, if ever, achieve the lofty hopes of success that accompany their birth. Alternative enhanced oil recovery (EOR) processes are still very much in need.
One of the most attractive alternative EOR possibilities in Lloydminster is, paradoxically, a variation of one that was tried and at one time rejected — in-situ combustion. Over the last two decades, the prospects for air injection have dramatically improved because of two developments. The first was the discovery of the reasons why in-situ combustion faltered in Lloydminster heavy oils. Chief among these was that it stalls when the powerful oil-banking character of a combustion front raises oil saturations to a level at which the combustion gases and injected air can hardly flow.
The second new development was the coincidental appearance of a solution to this operating problem. The advent of the progressive cavity pump led to many Lloydminster fields undergoing cold production, in which high conductivity channels, or “wormholes,” appeared as a result of sand production. These “wormholes” offer the opportunity to produce mobilized oil via a short path, not unlike the concept of a short production path as used in the THAITM process, another, distinctively different air injection process that is being tested in thicker, bitumen-type reservoirs.
Under this proposed third year of work on this topic, the implementation of a new air-injection EOR process is to be facilitated through two integrated projects, this one, and a companion project intended to facilitate a heavy oil field pilot. The project proposed here will help to elevate the existing knowledge of the chemistry of in-situ combustion to a level at which useful numerical simulations can be conducted to optimize field design.