我国陆相油田水形成的若干水文地球化学作用

Terrestrial oil-field water from the Upper Permian to Tertiary in China is charactorized by great variation in its chemical composition. According to the first three predominant ions oil-field water ean be classified into four categories, i.e., HCO2-Cl-Na, Cl-HCO3-Na, Cl-Na-Ca and Cl-SO4-Na, which are referred to as catogory A, B, C,and D for simplicity. From comparision of the features of oil-field water with those of terrestrial evaporation water, in conjunetion with available experimental results, five different hydrogeochemical mechanisms are suggested for oil-field water evolution. They are: the evaporation and concentration, the biochemical process, enrichment of trace elements, diffusion of petroleum components and various exchange processes ineluding the exchange of eations, dolomitization, isotope exchange and the reverse exchange of anions. Chemical characteristics and some regularities concerning oil-field water are interpretatod in terms of these mechanisms.