歧口凹陷热液流体活动及其对储集层的改造

Hydrothermal Fluid Activity and Its Reformation onReservoirs in Qikou Depression

为了明确富油气凹陷中热液流体活动的发育特征及其对储集层的改造作用,以渤海湾盆地歧口凹陷为研究对象,通过岩心、薄片、XRF元素扫描、扫描电镜观察和地层水矿化度、热解、包裹体均一温度、黏土矿物、微量元素、稀土元素、常规物性等资料,分析了歧口凹陷热液流体活动发育的证据,明确其对不同类型储层的改造方式,认为歧口凹陷中热液流体活动较为发育,对于储集层有较强的改造作用.研究结果表明:歧口凹陷中热液流体活动发育的标志包括热液角砾岩、斑马状结构、褪色泥岩和多种类型的热液矿物组合;地层水矿化度异常高;具有异常高Tmax或S1与S2值的泥岩;包裹体均一化温度超过正常热演化最高温度;浅层砂岩中高岭石质量分数异常高和中深层砂岩中绿泥石质量分数的异常高值;泥岩中Zn、Cd、Ba和Pb等微量元素出现异常高值;碳酸盐岩的稀土元素具有Eu正异常.不同类型储层中热液流体的改造方式具有差异性,碳酸盐岩中主要发育水力压裂作用和溶蚀作用,凝灰岩中主要发育水力压裂作用和促进脱玻化作用,玄武岩中主要发育水力压裂作用,热液流体通过溶蚀作用和促进绿泥石的发育来对砂岩储层进行改造.

In order to clarify the development characteristics of the hydrothermal fluid activity and its reformation effect on the reservoir in the oil-rich depression,the Qikou depression in the Bohai Bay basin was studied.Based on the analysis of core,thin sections,XRF,SEM,salinity of formation water,pyrolysis,homogenization temperature of inclusions,clay minerals,trace elements,REE and conventional physical properties,the evidences of hydrothermal fluid activity in Qikou depression of Bohai Bay basin were analyzed,and the reformation patterns on different types of reservoirs were identified.we regard that the hydrothermal fluid activity in the Qikou depression is relatively developed and has a strong reformation effect on the reservoir.The results show that there are several types of hydrothermal fluid activity indicators in the Qikou depression,including:hydrothermal breccia,zebra fabric,faded mudstone and several kinds of hydrothermal mineral associations;abnormally high formation water salinity;mudstones with abnormally high Tmax or S1 and S2 values;the homogenization temperature of inclusion exceeding the maximum temperature of normal thermal evolution;the abnormally high content of kaolinite in shallow strata sandstones and the abnormally high content of chlorite in mid-deep strata sandstones;the abnormally high characteristics of trace elements such as Zn、Cd、Ba and Pb in mudstones;the rare earth elements in carbonate rocks showing Eu positive anomaly.In different kinds of reservoirs,the reformation patterns of hydrothermal fluid are different:hydraulic fracturing and dissolution are mainly developed in the carbonate rocks,hydraulic fracturing and promoting devitrification are mainly developed in the tuff,hydraulic fracturing is mainly developed in the basalt,while the hydrothermal fluid reform sandstone reservoirs by dissolution and promoting chlorite development.