致密砂岩气藏损害特征及评价技术

致密砂岩气藏具有孔喉细小、 裂缝发育、 超低初始含水饱和度等特点， 在勘探开发过程中易受到损害， 其中水锁和应力敏感是最致命的损害方式。利用毛细管力自吸 －离心法、 Ｄ Ｐ Ｔ指数法和自研实验装置评价了致密砂岩气藏在过平衡和欠平衡条件下的水锁损害程度； 利用毛细管流动孔隙结构仪、 Ｃ Ｔ扫描等手段评价了致密砂岩气藏的应力敏感性。结果表明， 致密砂岩气藏有很强的水锁损害潜力， 即使在欠平衡条件下水相自吸对气藏仍然有一定程度的损害， 过低的欠压值不能达到有效保护储层的目的。随着有效应力的增加， 致密砂岩储层基块孔径明显减小， 裂缝渗透率大幅度降低； 在应力加载初期裂缝闭合程度较大， 后期减缓。在水基欠平衡钻井过程中，水锁和应力敏感的叠加效应使储层损害程度大幅度地增加。储层原始地层条件的真实模拟以及将室内评价实验结果与现场工程设计紧密结合是下步研究工作的重点。

DAMAGE CHARACTERISTICS AND ITS EVALUATION TECHNOLOGY OF TIGHT SANDSTONE GAS RESERVOIRS

With the characteristics of small throat,fractured and ultra-low initial water saturation,the tight sandstone gas reservoirs were likely to be damaged during the exploration and exploitation,the water blocking and stress sensitivity were the most fatal damage types. Spontaneous Imbibition-centrifuge,DPT index method and self-made experimental device were used to qualitatively and quantitatively evaluate water blocking damage degree under overbalance and underbalance condition. The stress sensitivity of tigh...