钻井液中无机盐对机械钻速的影响规律研究

Effect of Drilling Fluid Inorganic Salt on Rate of Penetration

改善钻井液性能来提高机械钻速,是目前降低钻井成本常用的技术手段之一。通过模拟恒压钻进试验,考察了钻井液中无机盐组分与砂岩岩石的相互作用及对机械钻速的影响,结合岩屑-溶液混合物的ξ电位,初步分析了其作用机理。结果发现,AlCl_3和Al_2(SO_4)_3具有较好的提速效果,A1Cl_3的浓度为0.01 mol/L时机械钻速能提高33.7%;通过ξ电位分析得出,Al^(3+)能够使含岩屑溶液的ξ电位由负值变为0,再转为正值,ξ电位大于一10 mV时提高机械钻速的效果明显。分析其主要原因是,ξ电位接近于0时岩石表面具有较高的表面自由能,有利于岩石破碎,这对提高机械钻速、降低钻井成本具有一定的意义。

Optimizing the performance of drilling fluids to increase the rate of penetration（ROP）is one of the most effective ways to reduce drilling cost. Through constant pressure drilling experiments, this paper investigates the interactions between inorganic salts in drilling fluids and sandstones, and their influences on ROP. The preliminary mechanism was analyzed combined with ζ potential of cutting-solution mixture. The results show that AlCl3 and Al2 （SO4）3 can effectively increase the ROP. The ROP was increased by 33.7% with AlCl3 concentration of 0.01 mol/L. The analysis of ζ potential shows that Al^3＋ can change the negative ζ electrical potential in cuttings to zero and then to positive. With the ζ electrical potential larger than -10 mV,the ROP is increased dramatically. With ζ electrical potential close to zero, the rock surface possesses a relatively high surface free energy which helps rock breaking. Accordingly,it increases the ROP and lowers the drilling cost.