塔里木盆地玉北地区奥陶系岩溶作用

摘要

奥陶系是塔里木盆地玉北地区海相碳酸盐岩油气勘探的重要目的层和产层。由于埋深大，勘探程度低，对储层方面认识有待进一步研究。通过钻井岩心、成像测井，结合岩石薄片、铸体薄片、阴极发光等资料，对玉北地区奥陶系岩溶作用类型和期次进行研究。结果表明，准同生溶蚀作用主要发育于良里塔格组沉积末期，为第一期方解石胶结物的溶解，偶见粒内溶孔、铸模孔和粒间溶孔，是后期溶蚀作用的基础。表生岩溶作用具多期次特点，其中加里东晚期至海西早期，岩溶作用最强，为奥陶系碳酸盐岩储层储集空间的主要形成期。埋藏溶蚀作用与油气活动带来的有机酸等物质有关，主要发育海西晚期和喜山期埋藏岩溶，具形成的溶蚀孔洞多不被方解石充填或半充填特征，是现今储层的有效储集空间。%The Ordovician becomes the target and production stratum for oil and gas exploration of marine carbonate rocks in YuBei area,Tarim Basin.Due to the deep burial and low degree of exploration,the cognition of its origin is not perfect and need to be further studied.Based on the drilling cores,imaging logging data,combined with rock and cast thin slice,cathodoluminescence, the type and period of karstification were analyzed.Penecontemporaneous karstification oc-curred in the late of sedimentary of Lianglitage Formation is the basis for later karstification, demonstrating with the dis-solution of first cements and the appearance of intragranular dissolved pore,moldic pore and intergranular dissolved pore. Supergene karstification has the characteristics of multi period,and between the late Caledonian to Early Hercynian,karst-ification which is most intense,is the main formation period of reservoir space in Ordovician carbonate rock.Burial dolo-mitization which has the relation with activities of oil and gas,can be divided into two main periods as the late Hercynian and Himalayan.And the dissolve pores which have not been filled with calcite or partly filled,is the effective reservoir space of current reservoir.