低渗凝析气藏防液锁成膜两性离子聚磺钻井液

Amphoteric/sulfonation polymer drilling fluid with performances of fluid-block prevention and film forming in low-permeability condensate gas reservoir

为了有效降低钻、完井过程中钻井液对储层造成的液锁损害,根据吐哈低渗凝析气藏储层特征,对液锁损害产生的机理和影响因素进行系统分析。应用界面张力仪法,评价了8种常用表面活性剂的表面张力,优选出降低表面张力能力较强的OP-10和ABSN;应用可视砂床压滤仪,研究了2种常用成膜剂对钻井液性能的影响和降滤失效果;应用防液锁、理想充填及成膜技术研制了适用于研究区块的防液锁成膜两性离子聚磺钻井液体系,体系中3种超细碳酸钙的复配比例为10%,40%,50%,总加量为4%。评价结果显示,该钻井液体系的API滤失量小于5 mL,高温高压滤失量小于10 mL,泥饼摩擦系数小于0.141,渗透率恢复率大于81%。

In order to effectively minimize damage of fluid blocking, the mechanism and influence factors of fluid blocking were analyzed according to reservoir characterics of Tuha low-permeability condensate gas reservoir. The surface tensions of 8 various commonly used surfactants were evaluated by using the interfacial tension apparatus, and the optimal results are OP- 10 and ABSN with better capacity of reducing surface tension. Influences of two various kinds of film forming agents on rheological properties and effect of reducing filtration were evaluated using visible sand-bed pressure loss apparatus. A system of amphoteric/sulfonation polymer drilling fluid with performances of fluid-block prevention and film forming was developed by techniques of fluid-block prevention, ideal packing temporary bridging and film forming. The combination proportions of three kinds of ultraline calcium carbonate in this drilling fluid are 10% ,40% ,50%, and total concentration is 4%. The properties of the low damage drilling fluid are as follows ： API loss is less than 5 mL, loss in high temperature and high pressure is less than 10 mL, friction coefficient of mud cake is less than 0. 141, regained permeability is over 81%.