Preliminary Laboratory Evaluation of Cold and Post-Cold Production Methods for Heavy Oil Reservoirs Part A: Ambient Conditions

Abstract The problem of post-cold production for conventional heavy oil (Lloydminster type) reservoirs is tackled. The topic is broken into two papers. In the current paper, laboratory work at ambient conditions is addressed. In Part B of the paper(1), parallel work at reservoir conditions is presented. First, an overview of related literature material is included. Then several experimental methods for additional heavy oil recovery are attempted in laboratory models. The methods tested include water flooding and polymer flooding. This work is offered as stimulus to consider the state of all cold produced heavy oil reservoirs and focus on the possible alternatives for this significant Canadian reserve. Introduction The heavy oil and oil sand deposits of Western Canada represent one of the largest hydrocarbon accumulations in the world with a resource base of nearly 1.7 trillion bbls(2). This is 1.5 times larger than the proven reserves of the entire Middle East. The bulk of the reserves are contained in three major geologically distinct regions. These areas are the conventional heavy oil of the Lloydminster area, the Carbonate Triangle, and the oil sands deposits. This work focuses on conventional heavy oil formations. Enhancement of primary production of heavy oil through the so-called cold production mechanism has been a popular topic in the heavy oil industry for the past 15 years. However, cold production alone cannot produce more than an estimated 10 - 15% of the original oil in place (OOIP). This paper addresses the issue of post-cold production or, more specifically, post-primary production of heavy oil via different injection techniques that include water flooding and polymer flooding. Several independent sets of experiments were run that included: one cold production experiment in a large cylindrical model with a central production well (radial production geometry), two linear core floods, four experiments at ambient conditions in rectangular geometry physical models, and six experiments at reservoir conditions in rectangular geometry physical models (one including sand production). The ambient conditions experiments are described here while in the accompanying paper(1), experiments at reservoir conditions are presented. Literature Survey A large variety of heavy oil EOR methods are proposed in the literature(3). Earlier work on non-thermal recovery of heavy oil did not take into account cold production mechanisms and thus it is questionable how such work will apply to the current state of the Canadian heavy oil fields. Notable is the work performed at the University of Alberta by Professor Farouq Ali et al.(4, 5). Wellbore productivity can be potentially improved by the creation of oil-in-water emulsions downhole. This can be achieved through the injection of a surfactant solution in the wellbore. This was tested with encouraging results, as reported by Norcen and SRC, in production wells that were hampered by water-in-oil emulsions(6). Carlson et al.(3) discussed a number of alternative methods for low cost recovery of heavy oil, describing a methodology for the screening of oil reservoirs and associated processes and listing a number of examples. Immiscible gas injection was one of the examples considered.

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