南翼山构造区油田卤水相关地层中岩石和矿物的沉积期后变化

Postdepositional Change of Mineral and Rock in Strata Related to Oilfield Water in Nanyishan Tectonic Area，Tsaidam Basin，Western，China

中文关键词:  油田卤水  矿物  沉积期后变化  南翼山构造区

英文关键词:Oilfield water  Mineral  Postdepositional change  Nanyishan tectonic area

中文摘要:

      油田卤水与油气的生成、运移和储集等各个阶段都密切相关，其形成及演化必定受烃源岩、油气运移通道所在地层和油气藏储集层等岩层在沉积期后所发生的水岩反应的影响。南翼山构造区油田卤水的储层为 N22y、N21y、N1g和 E23g,正好是该区油气的主要烃源岩和储集层，油气的运移也是在这些地层之中进行的。本文通过对这些地层的地表露头和油井岩芯或岩屑的岩石薄片进行镜下观察和鉴定，识别岩石及其组成矿物在沉积期后的变化。南翼山构造区油田卤水相关地层中的岩石和矿物在沉积期后曾发生过方解石和粘土矿物分别交代石英和长石、长石的绢云母化和粘土化、方解石白云石化、方解石的重结晶、灰(云)质岩的溶蚀、粘土矿物重结晶为黑云母、绢(白)云母、绿泥石和玉髓等，以及绢云母交代石英和长石、黑云母的白云母化和绿泥石化、黄铁矿的形成等方面的地球化学过程，也可见到硬石膏、天青石和铁方解石等自生矿物。岩石和矿物的这些沉积期后变化将为油田卤水形成及演化过程中水岩反应的深入研究提供岩石学和矿物学方面的证据。

英文摘要:

      Oilfield water is closely related to the stages of generation，migration and accumulation of hydro. carbon，and the postdepositional water-rock interaction in source rock，migration pathway and reservoir must influence its origin and evolution. The strata of N22y、N21y、N1g，and E32g are the reservoirs of oilfield water， which are also the source rocks，migration pathways and reservoirs of hydrocarbon in Nanyishan tectonic area. In this paper，to recognise the postdepositional changes of the mineral and rock in these strata，we observed and identified the rock thin sections of these strata (surface outcrops，and cores and drill cuttings) using thepolarizing microscope. The following were the main geochemical processes occurred during the postdeposi.tonal stages in these strata，replacement of quartz and feldspar by calcite and clay minerals，sericitization and clayization of feldspar，dolomitization of calcite，recrystallization of calcite，corrosion of limestone，recrystal. lization of clay minerals into biotite，muscovite (sericite)，chlorite and chalcedony，replacement of quartz and feldspar by sericite，muscovitizaton and chloritization of biotite，and formation of pyrite. Authigenic miner. als，such as anhydrite，celestite，and ferrocalcite，can also be observed in some thin sections. All of these confirm，petrologically and mineralogically，the water-rock interaciton during origin and evolution of the oil. field water in Nanyishan tectonic area.