深层油气用加重滑溜水压裂液体系

Study on Weighted Slick Water Fracturing Fluid for Deep Buried Oil and Gas

塔里木库车山前区块作为典型的超深层气藏,75%施工井泵压在100 MPa以上,最高施工压力达到136 MPa,压裂增产改造一直是制约其油气开发的技术瓶颈,施工排量也受到极大限制。据统计超深加重压裂液施工井,普遍存在液体密度增加,施工压力降低幅度未达到理论效果,基于理论分析及加重压裂液实际应用中存在的问题,借鉴页岩气用滑溜水成功应用的经验和加重压裂液的优点,通过优选加重剂、耐高盐降阻剂和助排剂形成了加重滑溜水体系。该体系加重密度为1.35 g/cm3,耐氯化钙35×104 mg/L,能有效降低施工压力和施工风险,降阻率为62%,与常规瓜胶压裂液减阻率相当,并具有良好的耐温耐剪切性能和助排性能,岩心伤害率为11.2%,对储层伤害低,为超高压超深井储层改造提供新的技术支持。

In fracturing the ultradeep gas reservoirs in the piedmont structure in Kuche,Tarim Basin,75%of the wells were operated at pump pressures above 100 MPa,the highest pump pressure being 136 MPa.The development of the gas reservoirs has long been limited by the fracturing operation because of the high pump pressures.Statistic data showed that when fracturing ultradeep wells,an increase in the density of the fracturing fluid did not result in the designed pump pressure decrease.Based on theoretical analysis and problems encountered in fracturing with high density fracturing fluids,a weighted slick water fracturing fluid was developed with several agents selected such as a weighting agent,a salt resistant friction reducer and a cleanup additive.In developing the slick water fracturing fluid,experiences of successfully using slick water in shale gas development were borrowed,and the advantages of weighted fracturing fluids were taken.The slick water fracturing fluid has a density of 1.35 g/cm3 and is resistant to the contamination by 35×104 mg/L of CaCl2.With this slick water,the operation pressure can be effectively reduced and operation risks minimized.Similar to conventional guar gum fracturing fluids,this slick water can reduce friction by 62%.The slick water has good high temperature stability and cleanup ability.It is resistant to shearing.Cores tested with this slick water had permeability impairment of only 11.2%.The development of the slick water fracturing fluid has provided a technical support to the stimulation of ultra-high pressure and ultradeep reservoirs.