热降解无黏土相钻井液实验研究

The system research on thermal degradation of clay free drilling fluid

针对海上钻井常用的弱凝胶无黏土相钻井液存在完钻后需要破胶问题,本文从体系增黏剂出发,通过对7种增黏剂的黏度和3种增黏剂的降解性优选评价出HVIS-9可作为热降解钻井液的增黏剂,其最佳加量为0.9%,在已有弱凝胶无黏土相钻井液处理剂的基础上建立了热降解弱凝胶钻井液体系,通过对该体系热降解性评价,所建钻井液体系在70℃、80℃、90℃三个温度条件下经过20 d的热降解,体系的表观黏度下降分别为48.15%、69.01%和79.25%;塑性黏度下降分别为43.75%、60%和73.33%,动切力下降分别为54.55%、80%和86.96%;所以该体系具有一定的热降解能力,更有利于储层保护。

Aiming at the problem of weak gel breaker to offshore drilling common clay free drilling fluid is drilled, the system of tackifier,the 7 tackifier viscosity and 3 tackifier degradation evaluation of HVIS-9 can be used as tackifier for thermal degradation of drilling fluid.The optimum amount of 0.9 %.In the existing weak gel clay free drilling fluid treating agent on the basis of the thermal degradation of weak gel drilling fluid system,through the system of thermal degradation assessment,the drilling fluid system at 70 ℃,80 ℃ and 90 ℃three temperature conditions after 20 days of thermal degradation,system the apparent viscosity decreased respectively 48.15 %, 69.01 % and 79.25 %.The plastic viscosity decreased to 43.75 %, 60 % and 73.33 %,respectively,54.55 % dynamic shear force decreased 80 %and 86.96 %.So the system has certain ability of thermal degradation, more conducive to reservoir protection support.