超低渗透油藏水平井穿层压裂技术研究

Researches of Technology of Translayer Fracturing of Horizontal Well in Ultra-Low Permeability Reservoirs

针对长庆油田超低渗透储层隔夹层发育、纵向非均质性强，部分水平井钻遇致密隔夹层难以压开的问题，开展了水平井穿层压裂技术试验。通过水平井定向射孔技术实现定方位、超深穿透射孔，确保裂缝穿过难压裂的开致密储层从而沟通主力贡献层，提高储层纵向动用程度；难压开储层已被射开多段，优选双封单卡压裂工艺实现选择性压裂；同时优化压裂工艺，采用前置酸预处理降低破裂压力，确保裂缝在隔夹层起裂；采用组合粒径＋螺旋式加砂方式，确保裂缝顺利延伸，保证施工安全，最终形成“定向射孔＋双封单卡”穿层压裂工艺技术。现场应用2口井，成功率达100％，平均单井日增油8．0t．增产效果明显．为后期继续开展低产水平井重复压裂提高单井产量提供了有效技术手段。

A trans-layer fracturing technology test with horizontal wells is launched in view of issues of development of interlavers and strong vertical heterogeneity in ultra-low permeability reservoirs, and part of the horizontal wells drilled into the light interlayers that are difficuh to fracture in Changqing Oilfield. The oriented and uhra deep perloration is realized by oriented perforating technology with horizontal wells. II ensures that the fractures go though the tight reservoirs that are difficuh to be fractured, thus the main contributive reservoirs are linked up. The vertieal utilization extent of the reservoirs is improved. The difficult-to-he-fractured reservoirs have been perforated on multiple sections. The authors choose straddle packers with a single slip to optimize the fracturing technology and realize selective fraeturing. Meanwhile the prepad acid pre-processing is adopted to reduce the breakdown pressure so as to ensure that the fractures begin to generate in the interlayers. The style of combing particle size and spiral sand application has been adopted to ensure the smooth extending of the fractures, thus guarantees the safety of the construction. The traversing fraeturing technique of ＂oriented perforation plus straddle packers with a single slip/anchor＂ is formed at last. Two wells have been utilized on site with the success rale as 100%. Average increased oil per day of the single well is 8.0 tons with significant stimulation effect. This supplies an effective technical measure for continuing to develop refracturing of low-production horizontal wells and raise the individual well production rate.