苏里格气田中深致密砂岩气藏压裂工艺技术初探

对于中深致密砂岩气层来说,由于储层非均质强,具有低压、低孔、低渗、岩性致密等特点,且存在严重的水锁损害和其它敏感性损害,采用常规砂岩储层的压裂改造方法效果不佳。根据低压致密气藏的储层地质特点,以苏里格气田为压裂工艺技术研究对象,收到了一定的效果。结果表明:1、研究的压裂液体系延迟交联时间大于60S,连续剪切120min的粘度大于60mPa.S,压后压裂液lh内破胶,破胶液粘度(1.71～4.75)mPa.S,残渣299mg/L,岩心渗透率损害率小于19.8%,表现出携砂性能好、滤失性小、流变性好及与地层流体配伍性好、易返排、对基质渗透率损害低的特征。2、气井助排剂、起泡剂优选使用,施工中液氮的伴注有利于压裂液的快速返排,减少压裂液对气层的伤害。3、不动管柱多层压裂及排液一体化工艺技术是集压裂、排液、求产、测压、测井温等一体的完整配套工艺技术。

On Fracturing Technology Used in Mid-Depth Gas Reservoir with Tight Sandstone in Sulige Gas Field

It is not effective to adopt fracturing technology suitable to general sandstone reservoir to transform mid-depth and tight sandstone gas layers which feature low pressure,low hole,low permeability and tight lithology because of their strong heterogeneity and in which there exist severe water-block damage and other sensitive damage.According to geological features of reservoirs of low-pressure and tight gas reservoir,the author has studied fracturing technology used in Sulige Gas Field.The result shows the followings:1.Delaying crosslinking time of fracturing fluid system studied is greater than 60s;viscosity after continuously cutting 120mm greater than 60mPa.s;and loss ratio of core permeability less than 19.8%,having the characteristics of high sand-carrying capability,low filtration,good rheological property,good compatibility with formation fluid,good flowback and low damage to matrix permeability.2.Optimal use of discharge aiding agent and foaming agent with liquid nitrogen’s filling in operation contributes to fast flowback of fracturing fluid,decreasing damage to gas bearing formation.3.Fixed string multilayer fracturing and flowing back technology is a full mating technology that gathers technologies including fracturing,flowback,production calculation,measuring pressure as well as temperature logging.