Enhanced Recovery Trends In Alberta

Abstract

Abstract Application of fluid injection schemes for the purpose of enhancing recovery from oil pools in Alberta has grown from very modest levels in the early 1950s to a current position in which about one-third of the original recoverable conventional oil reserves of the Province are attributed to enhanced recovery schemes. The growth of fluid injection operations bears a rather close relationship to the history of development of the major geological plays in the Province over the twenty-year period. The types of schemes implemented and the recovery improvements generated have been governed by prevalent technology, and other factors such as well spacing practices unitization and levels of market demand. The slackened rate of finding new oil pools combined with the burgeoning demand for crude oil should lead to more attractive price/cost relationships, which in turn should generate new technologic innovations in reservoir displacement and well operating mechanics. Future trends in enhanced recovery operations may be forecast by a consideration of the amounts of oil not recovered by present depletion methods and the risks and potential benefits of emerging enhanced recovery techniques. Introduction IS ESTIMATED that by the end of 1972, some 33 billion barrels of crude oil initially in place had been discovered and developed in some 1400 separate pools within the Province of Alberta. These pools cover a combined area of nearly 3000 square miles and are drained by some 14,000 producing wells. Of the total oil in place, about 33 per cent or 11 billion barrels is believed recoverable by the mechanisms currently being applied. Particularly in the past fifteen years, concerted efforts have been taken to improve the recovery from oil pools in Alberta. As a result, some 3.7 billion barrels of crude oil, or approximately one-third of the total original recoverable reserves, are now directly attributed to the application of enhanced recovery techniques. The more significant of these schemes are distributed across the Province roughly as shown in Figure 1. Today there are about 350 enhanced recovery schemes operating in the Province, containing a total of 2600 injection wells with a combined daily injection of 1.6 million barrels of water, 136 million cubic feet (3) Solvent Floods – horizontal, vertical. At the end of 1972, the reserves attributed to the major recovery mechanisms being applied in Alberta oil pools were divided in the manner shown in Table 2. Based on these statistics, the following observations can be made: water flooding- accounts for nearly 90 per cent of the additional oil recoverable by fluid injection schemes; gas flooding has been negligible; vertical flooding is much more efficient than horizontal flooding; vertical solvent flooding, with an over-all recovery factor of 85 per cent, is the most efficient displacement process being applied. Although the over-all gain in recoverable reserves of some 3.7 billion barrels is respectable, the challenge of the next decade here in Alberta may be expressed this way: