陆相页岩油固井滑套单簇孔压裂技术与效果评价

Technology and result evaluation of well cementing sliding sleeve single-cluster hole fracturing for continental shale oil reservoir

针对渤海湾盆地沧东凹陷孔二段陆相页岩岩性变化大、非均质性强,传统压裂导致页岩油水平井产量差异大的问题,在G108-8井500m岩心精细描述基础上,通过GY5-1-9H井固井滑套压裂工艺试验、多簇孔与单簇孔对比压裂模拟实验,总结了单簇孔压裂在断陷盆地陆相页岩油压裂适应性、机理及压裂施工经验。研究表明,固井滑套单簇孔压裂的裂缝开启均匀度较桥射多簇孔压裂可大幅提升1.65~2.04倍,克服了桥射多簇孔压裂靠竞争起裂导致的有些簇孔压不开,有些簇孔裂缝突进、窜扰,以致套管变形的难题。固井滑套单簇孔压裂工艺可减少泵送桥塞和射孔环节,施工流程更加连续,单日最多连续完成11级压裂施工,施工压力低20%~30%,压裂车组也由20台减少到9台。GY5-1-9H井应用该工艺实现单簇孔压裂79级987m,滑套间距(簇孔间距)12.5m,压裂后首年累计产油10128t,预测最终可采储量(EUR)3.77×10^(4)t,创造了国内页岩油水平井归一化千米井段首年累计产油和单井EUR最高纪录,是同富集区桥射多簇孔压裂井的1.34~3.15倍。该工艺在冀中坳陷束鹿凹陷应用也实现了页岩油水平井超300天的稳压稳产。

In Cangdong Sag of Bohai Bay Basin,the continental shale in the second member of Kongdian Formation(Kong 2 member)has great variation in lithology and high heterogeneity,and shale oil production of horizontal wells is significantly different by applying traditional fracturing technologies.In view of these problems,core section with a length of 500 m in Well G108-8 has finely been described,and well cementing sliding sleeve fracturing technological test in Well GY5-1-9H and comparative fracturing simulation experiments between multicluster hole and single-cluster hole have been conducted,which enable to summarize the adaptability,mechanism,and fracturing construction experience of single-cluster fracturing technology for continental shale oil in fault basins.The study results show that the uniformity of fracture initiation by using well cementing sliding sleeve single-cluster hole fracturing has significantly been improved by 1.65-2.04 times compared to bridge plug multi-cluster hole fracturing,overcoming the failure of fracture opening in some clusters due to competitive fracture initiation,as well as problems of casing deformation caused by fluid fingering advance and frac-hit in some clusters.The process of bridge plug pumping and perforation is eliminated when applying well cementing sliding sleeve single-cluster hole fracturing technology,so the construction process is more continuous.A maximum of 11 stages of fracturing construction have continuously been operated in one day,with a construction pressure reduction of 20%-30%,and the number of fracturing trucks decreased from 20 to 9.In Well GY5-1-9H,this technology has been applied to implement single-cluster hole fracturing for 79 stages and 987 m,with a sliding sleeve spacing(cluster hole spacing)of 12.5 m.After fracturing,the cumulative oil production in the first year was 10128 t,and the predicted ultimate recoverable reserves(EUR)were 3.77×10^(4) t,setting a record for the highest cumulative oil production and single well EUR of the normalized per kilometer section in shale oil horizontal well in China,which was 1.34-3.15 times that of multi-cluster hole fracturing wells in the same oil enrichment zone.It has also been applied in Shulu Sag in Jizhong Depression,and the steady pressure and production have been achieved in shale oil horizontal wells for over 300 days.