深井水基钻井液流变性影响因素的实验研究

Research on Factors Affecting the Rheology of Water Base Drilling Fluid in Deep Wells

针对室内配制的水基钻井液,主要考察了配浆土的种类及配比、自制高温护胶剂GHJ-1加量、以及钻井液密度对水基钻井液黏度、切力等流变参数的影响,另外还考察了钻井液老化温度和老化时间的影响。实验结果表明,低密度固相是影响水基钻井液高温流变性的主要因素,适当控制钻井液中黏土含量和采用抗高温的抗盐土海泡石,可以有效控制高密度水基钻井液的高温流变性,在中低密度(1.5g/cm^3)盐水钻井液中保持黏土总量为3%、钠膨润土海泡石为1:2,在高密度盐水钻井液(1.8g/cm^3)中保持黏土总量不超过2%、钠膨润土:海泡石为1:1时,有利于流变性的控制。GHJ-1加量为1.0%～1.5%时钻井液的流变性能较理想,在GHJ-1存在下,老化温度和老化时间对钻井液流变性影响较小,在维护处理时注意适当补充处理剂的浓度,才能维持钻井液流变参数在合理的范围内。

Studies are conducted on the effect of clay(species and concentration),the concentration of a high temperature colloid protection agent GHJ-1,mud density,aging temperature and aging time on the rheology of water base drilling fluids.The experimental results show that major factor affecting the high temperature rheology of a water base drilling fluid is the concentration of low gravity solids(LGS).Using high temperature salt clay(sepiolite) and controlling the concentration of low gravity clay in water base drilling fluid effectively stabilize the high temperature rheology of the fluid.For example,in a water base drilling fluid of 1.5 g/cm^3,maintain a total clay content of 3%and a sodium bentonite:sepiolite ratio of 1:2,or in a water base drilling fluid of 1.8 g/cm^3,maintain a total clay content of less than 2%,and a sodium bentonite:sepiolite ratio of 1:1,will be beneficial to the stabilization of rheology.A satisfactory rheology can be obtained at a GHJ-1 concentration of 1.0%～1.5%.The presence of GHJ-1 in a water base drilling fluid minimizes the influence of aging temperature and aging time on rheology.A timely addition of certain additives is crucial to having a stable rheology.