摘要
致密砂岩气藏在勘探开发过程中极易产生严重的水锁损害，造成气井产能下降。文中以塔里木盆地M区块致密砂岩为研究对象，采用真空饱和、恒压驱替、核磁共振相结合的手段开展了不同因素对水锁损害率的影响实验。实验结果表明：岩心初始含水饱和度越低，水锁损害率越高，当初始含水饱和度为15%和35%时，驱替120 min后水锁损害率分别为74.5%和59.1%；含裂缝岩心水锁损害程度明显低于基质岩心，岩心中黏土矿物质量分数、实验流体矿化度和黏度越高，水锁损害率也越高，而实验流体表面张力越小，水锁损害率越低。塔里木盆地M区块施工时，应选择合适的作业流体和施工压差，尽可能减少作业时间，降低水锁损害程度。另外，可以通过增大生产压差、水力压裂、注入解水锁剂及干氮气等措施解除水锁损害。
Abstract
Tight sandstone gas reservoirs are prone to serious water lock damage in the process of exploration and development, resulting in the decline of gas well productivity. Taking the tight sandstone in block M of Tarim Basin as the research object, the effects of different factors on water lock damage rate were carried out by means of vacuum saturation, constant pressure displacement and nuclear magnetic resonance. The results show that the lower the initial water saturation of the core, the higher the water lock damage rate. When the initial water saturation is 15% and 35%, the water lock damage rates are 74.5% and 59.1% respectively after 120 min displacement. The damage degree of water lock in fractured core is obviously lower than that in matrix core. The higher the content of clay minerals in rock core, the higher the water lock damage rate. The higher the salinity and viscosity of the experimental fluid, the higher the water lock damage rate, and the smaller the surface tension of the experimental fluid, the lower the water lock damage rate. It is recommended to select appropriate working fluid and construction pressure difference during the construction of block M, and reduce the operation time as much as possible to reduce the damage degree of water lock. In addition, water lock damage can be relieved by increasing production pressure difference, hydraulic fracturing, injecting water lock releasing agent and dry nitrogen.
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