油藏开发地球化学技术研究的新动态——石油开采过程的地球化学

对注水开发的油田,由于向油层内大量注水,使地层原油粘度增加;注入水在与原油接触时,将溶解一部分地层原油中的轻质组分;注入水使油水乳化。随着注水井开始注水,造成地层的压力升高,从而使原油中轻分子量化合物的含量增加,原油的产量增加;原油可以重新溶解蜡质,使得原油的蜡含量升高;一部分沉淀在大孔隙中的沥青质与一些可溶的沥青质松散地连接,在注入水驱替的过程中,也可以流出,造成生产过程中沥青质含量的增加。火烧油层则与原油的化学组成密切相关 :饱和烃在火烧油层中首先燃烧,在低温阶段释放出大量的热能,影响火烧层的前沿面;到了高温氧化阶段,沥青质发生反应,并释放大量的热能,影响火烧油层的持续性。二氧化碳驱则可能导致沥青质从原油中分离并沉积在油藏中。

NEW DEVELOPMENTS ON GEOCHEMICAL TECHNIQUE OF OIL EXPLOIT:GEOCHEMISTRY OF OIL PRODUCTION

The physical and chemical properties of oil will change as oil production increases.Water flooding is a technique used most for oil production,the miscosity of oil increases because a lots of water enter into strata which contact with oil and bring some light crude oil components.At the same time,the water flooding will also cause emulsification of oil. As the water flooding increases,formation pressure will go up and lead to the enrichment of light components.As a result,the yield of oil also increases.The oil can also dissolve wax and cause the increase of wax content.Some asphaltene components in the pore which loosely contact with rock can be expulsed during water flooding process.This increases the asphaltene content of oil production.Combustion is another important techmique for heavy oil production.The combustion behavior is closely related to the SARA fraction of oil.Saturated hydrocarbon begin to burn first,release some energy in low temperature stage and affect the combustion front.In high temperature stage,asphaltene begin to react and release large amounts of heat,affect the succession of combustion bed.The third technique is CO 2 flood used in some oil fields.These processes will increase in oil API gravty with precipitation of heavy components from oil phase due to CO 2 injection.