变质岩潜山体积压裂技术探索与实践

Exploration and Practice of Stimulated Reservoir Volume Fracturing Technology for Metamorphic Rock Buried Hills Reservoir

辽河油田变质岩潜山油藏储量丰富,但普遍存在储层物性差、自然产能低等问题,需要进行压裂改造以获得工业油气流。由于储层厚度大,需要大规模加砂压裂改造,但常规方法加砂困难,施工成本高。在常规压裂技术的基础上,将体积压裂思路引入裂缝型变质岩潜山油藏。通过理论计算、数值模拟等方法 ,论证了此类储层实施体积改造的可行性,优选分簇射孔方式,优化低黏、低摩阻滑溜水压裂液,采用大排量、低砂比施工工艺,实现对天然裂缝的最大程度沟通,极大地提高储层整体渗透率,实现储层的立体改造。井下微地震裂缝监测结果显示,与常规瓜胶压裂相比,滑溜水压裂裂缝波及体积明显增大。该技术于2013年开展先导试验以来,累计实施18井次,压后平均单井日增油10.1t/d,是同区块常规压裂日产量的2.2倍,同时射孔及压裂费用总体降低15%以上。

The metamorphic rock buried hill reservoirs in Liaohe oilfield have a large amount of reserves.Be-cause of its poor physical property and low natural productivity in reservoirs,most wells drilled in the field have to be fractured for industrial oil and gas.Large-scale sand fracturing should be made because of large thickness of reservoirs.But massive hydraulic fracturing is difficult for sanding with high cost.Based on conven-tional fracturing technologies,stimulated reservoir volume（SRV） fracturing was introduced and applied to the fractured metamorphic rock buried hills reservoirs.Theoretical calculation and numerical simulation results prove its feasibility.Clustering perforation mode,slick water fracturing fluids with low viscosity and low friction were optimized.After the technology was applied with high rate of fracturing fluids and low proppant concentration,maximum communication among the natural fractures may be realized,the overall permeability of the reservoirs may be greatly improved,and three-dimensional treatment of the reservoirs may be realized.Downhole micro-seismic fracture monitoring results indicate that the induced fracture volume by the slick water fracturing in-creased obviously compared with that by conventional guar gum fracturing.Since pilot tests were made in2013,the technology was applied for 18 cumulative well-times,and average oil production of single well increased by 10.1t/d after fracturing,which is 2.2 times of that by conventional fracturing.The cost of perforation and fracturing decreased by more than 15% in general.