SAGD as Follow-Up to Cyclic Steam Stimulation in a Medium Deep and Extraheavy-Oil Reservoir

Abstract

Abstract Guan-tao oil layer of Shu 1 Block in Liaohe oilfield is a medium deep and extra heavy oil reservoir, which has high porosity and high perm with edge water. In 2001, cyclic steam stimulation was applied with square well pattern and well-space 70m. After 9-10 cycles the stimulation development effect deteriorated and the degree of reserve recovery was only about 15%. To seek development method of extra heavy oil reservoir and improve the entirety recovery ratio of this block, after the feasibility research on SAGD technology in Guan-tao oil layer was finished, horizontal wells were infilled between vertical wells and 4 SAGD pilot test well groups combining vertical wells with horizontal wells were conducted Three cycles of cyclic steam stimulation to preheat the formation and decrease pressure were proceeded and the 4 well groups had produced for 1 year after converted to SAGD. Daily oil production capacity of single horizontal well increased from the initial 20-40t/d to 70-80 t/d after the multiple adjustment of the injection-production parameters. Preferable period effect was accomplished and the test provides good guide for same medium deep and extra heavy oil reservoir to change their development methods.