常用处理剂对岩心的损害

Study on Damage of Core by Mud Additive

介绍了评价钻井液处理剂对岩心损害程度的减饱和度半渗隔板法。先后用7种常用处理剂的3％KCI水溶液和6．5％NaCl水溶液基准液饱和不同岩心，测定岩心饱和后的毛管压力曲线，并分别求出岩心内液体开始排出时相应的毛管压力Pd、岩心含湿相饱和度50％时相应的毛管压力P50和241kPa压差下岩心的残余湿相饱和度Sr。结果表明，处理剂类型、浓度和岩心的原始渗透率是影响毛管压力的主要因素。表面活性剂大部分都能降低Pd、P50及Sr值，且降低幅度随浓度增高而增大，这有助于减轻液相对岩心的损害；其它常用有机处理剂试液均使Pd、P50及Sr值增大，对岩心均有不同程度的损害：岩心原始渗透率越低，外采液体引起的损害越严重。

The surface tension of some 3 percent potassium chloride/organic mud additive solutions,and the curve of capilary pressure versus liquid saturation are determined. With these curves,the threshold pressure of draining liquid Pd,P50,and the residual liquid saturation at 241 MPa are calculated. According to these curves and the said 3 parameters,the damage of core by mud additives can be evaluated.