Abstract

The problem of cold and post-cold production for heavy oil [Lloydminster type] reservoirs is addressed. First, an overview of cold production related material is presented. The reservoir state is postulated based on behaviour of laboratory systems. Then several experimental methods for additional heavy oil recovery are attempted in the same cold produced laboratory models. The methods tested include water flooding, gas flooding, and polymer flooding. The effect of sand production is evaluated. The results are very preliminary, but encouraging. This work is offered as a challenge for the industry 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 represents one of the largest hydrocarbon accumulations in the world with a resource base of nearly 1.7 trillion bbls. 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 Lloydminster area, the Carbonate Triangle, and the oil sands deposits.

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 fifteen 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 in general post-primary production of heavy oil via different injection techniques that include water flooding, polymer flooding or pressure pulsing / shut-in. Several independent sets of experiments were run that include one cold production experiment in a large cylindrical model with a central production well (radial production geometry), 2 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).

LITERATURE SURVEY

A large variety of heavy oil EOR methods are proposed in the literature1. Earlier work on non-thermal recovery of heavy oil did not take into account cold production mechanisms and thus it becomes questionable how such work will apply to the current state of the Canadian heavy oil fields. Notable is the work performed in the University of Alberta by the group of Prof. Farouq Ali2,3. Some more recent work includes the following:

Productivity improvement through enhancements of primary production has been a relatively recent exercise of the oil industry and was led by Amoco4. Amoco's main focus has been in the development of primary production technology in areas previously thought not to be capable of such production. Most of the early reported work deals with the Elk Point / Lindberg sands, where live oil viscosities range from 2000 to 55,000 cp at reservoir temperatures. It was found that sand production increases the productivity of the producing interval and allows for greater fluid flow rates to the wells.

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