超低渗浅层油藏水平井钻井技术难点与突破

Technical difficulties and breakthroughs in drilling horizontal wells in shallow and ultra-low permeability reservoirs

针对延长东部油区低渗—超低渗储层埋深浅,地层压力低,常规井开发井多、低产、低效问题日益突出的难题,以及水平井开发受低温、低压、埋深因素干扰,建井难度高的问题,开展了浅层—超浅层大位移水平井钻完井配套技术研究与应用。创新水平井钻井压裂一体化理念,针对压裂后易形成水平缝的低压浅层油藏,采用"弓形"水平井设计方法,配合浅层缝网压裂技术,比常规水平井的水平段提高至少30%的动用水平,实现了低垂向应力储层的高效动用;采取井眼轨道与井身剖面协同优化设计,采用低成本钻井加压技术,配合下套管优化技术,提高钻柱轴向压力及传输效率,实现了多口高难度水平井的成功建井。为提高延长东部浅层超低渗油藏开发效果,提供了坚实的技术支撑,具有较高的经济效益和社会效益。

Eastern Yanchang oilfields, production using conventional walls（which have already been more）caused problems of low productivity and low efficiency in shallow, low-pressure,low-permeability and ultra-low permeability reservoirs. However, it is difficult to drill horizontal wells in such reservoirs （at low temperature, low pressure and shallow depth）. To solve these problems, supporting techniques for drilling and completion of extended-reach horizontal wells were： studied and applied in shallow and ultra-shallow layers. The innovative combination of ＂arcual＂ horizontal well with shallow fracture network in shallow and low-pressure reservoirs where horizontal fractures are easily induced by fracturing stimulation increased more producing reserves by at least 30% than conventional drilling method in a horizontal section, obtaining effective production of reservoirs with low vertical stress. The collaborative optimization design of well trajectory and well profile, low- cost pressuring, casing optimization, increase of the axial pressure and transmission efficiency of drilling string were applied and created successful construction of many horizontal wells in very complicated conditions. This study provides solid technical support for improving the development of shallow and ultra-low permeability reservoirs in eastern Yanchang oilfields with more economic and social benefits.