Case Analysis on Hydrocarbon Alternative Gas Miscible Flooding in PuBei Oil Field

Abstract

The oil field in China with the method of development by miscible flooding is scare, to sum up the experiences, this paper analyses the developments of Pubei oil field which is the first sand oil reservoir to perform hydrocarbon miscible flooding in China. It has integrated, good connecting formation with undeveloped cracking system and permeability of 110.5×10~(-3)μm~2. It is a typical volatile oil reservoir. The minimum miscible pressure (MMP) is 33MPa. The Injected gas is the by-produced gas in the oilfield. The results of core flooding experiments showed that oil recovery by primary gas injection is higher than primary water injection. To chose one best method, the field was developed by primary water injection at east and primary gas injection at west, keeping formation pressure at 35MPa. At early exploration time, there were seven injection wells and eight production wells. Now, there are nine production wells and two gas injection wells, seven water injection wells. The velocity of oil production is 44t/d, gas injection is 14.55×10~4m~3/d, water injection is 144m~3/d. It has developed for three years till October 2001; the oil recovery is 19.05%, the synthetic water saturation is 3%. There are certain increases of GOR in some production well but no obvious gas breakout. Primary water injection well cannot change to gas injection since gas cannot be injected after water injection, so cannot perform GAW in east area. This paper introduces general geometry character, basic experimental study, exploration performance, and existing problem of the reservoir and gives some proposals, which is helpful in exploration the similar oil reservoir by miscible flooding.