The A East Haradh formation contains a 200-m-thick oil column of highly viscous oil, with viscosity ranging from 200 to 400,000 cp. Because of the high viscosity, first production was considered possible only by the use of thermal enhanced-oil-recovery techniques, starting with cyclic steam stimulation (CSS). This paper presents key learnings derived during this initial-operations phase of CSS in the A East Field, including key trial results on different well completions and artificial-lift systems.
In light of the results of a new geochemical characterization study of the crude extracted from a core, cold production was deemed feasible in the crestal area of the field. Viscosities at the top of the Haradh were estimated at 200 cp, lower than previously thought, and progressing cavity pumps (PCPs) were installed in 32 wells to start a cold-production phase.
Cold production started in March 2013 and lasted until the end of 2014, when all wells in the field were converted to CSS. The cold-production period allowed early depletion of the reservoir and later improvement in steam injection. A pressure drop of up to 20 bar was observed, and fluid-level measurement in the wells and PCP performance suggested good pressure communication between the wells.
Despite some early challenges, first CSS production was promising and, within a few months, was ramped up to 70% of the targeted CSS field peak oil rates....
Key Learnings From First 2 Years of a Full-Field CSS Development in Oman
01 March 2017