Abstract
This study presents an experimental investigation of heavy-oil recovery by steam injection in a three-dimensional model containing 17° API crude oil. The first part of this paper describes the experimental apparatus. Emphasis in this paper is on the effect of the combination of horizontal and vertical wells on steam-injection efficiency. Four cyclic steam-injection experiments were conducted. Two used a vertical well at the center of the model, and two used a horizontal well scheme, showing better oil recovery and steam/oil ratios than the vertical well scheme. Soak time as well as the amount of steam injected per cycle were investigated. For both schemes, small slug sizes seem to gave initially better steam/oil ratios than expected, however, cumulative oil recovery for vertical wells do not depend on slug size, while for horizontal wells, small slugs followed by larger slugs gave a better recovery by 8% of the original oil-in-place (OOIP), compared with large slugs followed by smaller ones. Steam-drive experiments were conducted in three different well configurations: (a) a vertical injector and horizontal producer, (b) horizontal injector and producer, and (c) injector and producer both vertical. The combination of two horizontal wells gave by far the best results. Temperature data show that the use of horizontal wells gives a better sweep efficiency and reduces gravity override of steam. This paper demonstrates the potential of using horizontal wells for steam injection. In cyclic operations, the use of horizontal wells improved the recovery by 30–50%. In a drive process, the recovery using two horizontal wells was 70% higher than the vertical wells configuration.
Published Version
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