海上零散薄油藏地层自流注水开发实践

Development Practice by Dumping Injection in Scattered-thin Reservoirs of Offshore Oilfields

零散薄油藏由于油层薄、油砂体小、储量分散、天然能量弱,采用常规定向井方案开发效果较差,采用水平井开发虽然可以有效改善初期单井产量,但由于地层能量不足,单井产量递减快,无法从根本上解决采收率低下问题。采用注水开发方式,虽然能解决地层能量不足问题,但增加平台注水设施和钻专用注水井等将使开发成本大幅提高,有可能因经济效益变差而无法开采。研究和我国海上开发实践表明,在精细油藏描述基础上,采用多底、多分支水平井及"地层自流注水"技术相结合的开发模式可以有效突破海上分散状薄油层开发的经济瓶颈,与常规的不注水定向井方案相比其单井产量可提高6～10倍,采收率提高10个百分点以上,为海上油田中后期挖潜以及低丰度、难动用储量的有效开发探索出一条新的途径。

Because in scattered-thin reservoirs,sand body was small,reserves were scattered,natural energy was insufficient,production effect was poor when it was developed by conventional directional wells.Though horizontal well could effectively improve the initial production of single well,energy was insufficient in formation and production was declined quickly,the problem of low recovery ratio could not be resolved fundamentally.Water-flooding could resolve the problem of insufficient energy,but the water injection equipment and injection wells would induce the highest cost of development,by which production would be ineffective for poor economic effect.The research and development practice of China's offshore oilfields indicate that based on fine reservoir description,multi-bore and multi-branch horizontal wells are used to break the economic bottlenecks of development of scattered-thin reservoirs in combination with dump injection technology.By using the new scheme,the single well production would be raised for 6to 10times and oil recovery would be raised for 10%compared to the conventional production scheme.The study result provides a new way for tapping the potential in the reservoirs with low abundance and hard-to-produce reservoirs of offshore oilfields.