葡北油田气水交替注烃混相驱开发研究

CASE ANALYSIS ON HYDROCARBON ALTERNATIVE GAS MISCIBLE FLOODING IN PUBEI OIL FIELD

对我国第一个注烃混相驱开发的砂岩油田葡北油田进行实例分析 ,该油田储层渗透率 110 .5× 10 -3 μm2 ,构造完整 ,连通性好 ,断裂系统不发育 ,属典型挥发性油藏 ,最小混相压力 (MMP)为 33MPa ,注入气为油田伴生气。长岩心的实验表明先注气比先注水原油采收率更高 ,为了对比先注气还是先注水好 ,采用东边先注水西边先注气的开发方式 ,地层压力保持在 35MPa ,早期采用 7采 8注共 15口井开发 ,到目前有采油井 9口 ,注气井 2口、注水井 7口 ;区块日产油 4 4t,日注水 14 4m3 ,日注气 14 .5 5× 10 4m3 ,到 2 0 0 1年 10月 ,已开发 3年 ,原油采出程度 19.0 5 % ,油田综合含水 3% ,有部份井气油比有所上升 ,但未出现气明显突破现象。设计是气水交替 ,但由于水井转注气注不进而未能实施。介绍了油田地质概况、基础研究实验、方案设计、开发情况、动态监测、实施中存在的问题等 ,并提出了相关建议 。

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.