碳酸盐岩Zeta电位影响因素研究

Influencing Factors Research of Zeta Potential of Carbonate Rock

储层岩石界面电性对原油采收率具有重要的影响,考察了矿物组成、无机盐、pH值、极性物质以及表面活性剂对碳酸盐岩Zeta电位的影响。结果表明,天然碳酸盐岩中方解石含量越大,其相应的Zeta电位就越趋向于正值;Ca^(2+)比Na^+对碳酸盐岩Zeta电位影响大,可使Zeta电位由负值转变为正值;溶液p H增大使得碳酸盐岩Zeta电位减小,但在Ca^(2+)的影响下,碳酸盐岩Zeta电位降低幅度较小;碳酸盐岩吸附极性物质后Zeta电位变大,这与极性物质改变碳酸盐岩表面润湿性相关;在表面活性剂溶液中的碳酸盐岩Zeta电位的正负由表面活性剂的电性所决定,表面活性剂对碳酸盐岩Zeta电位的调控能力与表面活性剂在岩石表面的吸附能力有关。这些研究结果不仅阐明了碳酸盐岩与不同流体之间的界面电性,而且也有助于理解碳酸盐岩油藏提高采收率的机理。

Interfacial electrical property of reservoir rock has an important effect on oil recovery. The influence of the mineral composition,inorganic salt,p H,polar material and surfactants on Zeta potential of carbonate rock was investigated. The results show that: the Zeta potential tends to be positive when the content of calcite in the natural carbonate rock increases; the effect of Ca^(2 +) on the Zeta potential is larger than that of Na^+,and Ca^(2 +) can change the Zeta potential from negative into positive; the increase of p H of the solution reduces the Zeta potential,and the reduction extent of Zeta potential is smaller under the influence of Ca^(2 +); the Zeta potential increases when the polar material is adsorbed on the carbonate rock,which results from the change of surface wettability of carbonate rock due to the polar material; the Zeta potential of carbonate rock in the surfactant solution is decided by the electrical property of the surfactant,and the regulation ability of surfactant to the Zeta potential is in relation to the adsorption of surfactant onto the rock surface. These research results will not only provide a clear understanding of the interfacial electrical property between the carbonate rock and the formation fluids with different material,but also help to elucidate the mechanisms of improved oil recovery in the carbonate reservoir.