Case Story: Line Driving Horizontal Producer/Injector Patterns Increasing Recovery for Thin Carbonate Reservoir, Oman

Abstract

AbstractBlock B is located in northwest of Oman basin and its target formation is thin Early Cretaceous Shuaiba limestone reservoir with high porosity and low permeability. The reservoir is confined by faults towards northeast and southwest and trapped by lithology towards northwest and southeast. It was brought on stream in 1990 with vertical producers and the development situation was deteriorated heavily for years of natural depletion.Based on the detail geological and reservoir engineering study, the line driving horizontal producer/injector patterns along the striking of the faults were optimized and implemented in the full block. During the early stage of water injection, the ratio of injection/production was about 3 to restore the formation pressure as soon as possible and made the free gas dissolve back into the oil. When the formation pressure was resumed to about bubble point pressure, the ratio of injection/production was reduced for balance. Close monitoring of production performance and streamline study were carried out to guide the magnitude of production and injection and keep the waterflooding front advancing evenly to increase the sweep efficiency. As of Dec., 2010, great success was achieved as the oil rate was increased from less than 2,000b/d at the depletion stage to 10,000b/d and the recovery factor was about 30%.