微电阻率扫描成像测井在沉积环境识别中的应用

Application of micro-resistivity scanning imaging logging in sedimentary environment recognition

利用FMI成像资料进行沉积相分析,特别之处是能够对地层进行长井段连续的观察和描述,获得丰富的岩性、层理、剖面旋回等重要的岩石结构和沉积构造方面的信息,而相分析的具体方法与常规地质分析完全相同。本井FMI测量井段自下而上为上奥陶统五峰组、下志留统龙马溪组与小河坝组底部地层。通过成像测井分析认为上奥陶统五峰组为灰黑色粉砂质泥岩,含笔石化石,为水流不畅的停滞盆地沉积。下志留统龙马溪组下部为灰黑色粉砂质泥岩、泥岩以及黑灰色泥、页岩、粉砂质泥页岩,含笔石化石,为停滞盆地沉积;龙马溪组中部为黑灰色、灰色泥质粉砂岩、粉砂岩夹粉砂质泥岩、泥岩,泥岩发育水平层理,泥质粉砂岩、粉砂岩发育变形构造、块状层理,底部见冲刷面,为浊流沉积;龙马溪组上部为深灰色及灰色泥岩夹粉砂质泥岩、薄层粉砂岩,泥岩发育水平层理,见变形构造、包卷层理,为浅海陆棚夹浊流沉积。FMI测量小河坝组底部为灰色泥岩、粉砂质泥岩,为浅海陆棚沉积。

Using FMI imaging data for sedimentary facies analysis,the special feature is the ability to continuously observe and describe the strata in long wells,and obtain rich information on lithology,bedding,profile cycles and other important rock structures and sedimentary structures.The specific method of facies analysis is exactly the same as that of conventional geological analysis.From bottom to top,the FMI measurement section of this well is the bottom strata of the Upper Ordovician Wufeng formation,Lower Silurian Longmaxi formation and Xiaoheba formation.Through imaging logging analysis,it is believed that the Upper Ordovician Wufeng formation is gray-black silty mudstone,containing graptolite fossils,and deposited in stagnant basins with poor water flow.The lower part of the Lower Silurian Longmaxi formation is gray-black silty mudstone,mudstone,and black-gray mud,shale,and silty mudstone,containing graptolite fossils,which are stagnant basin deposits.The middle part of the Longmaxi formation is black-gray,gray argillaceous siltstone,siltstone intercalated with silty mudstone,mudstone,mudstone developed horizontal bedding,argillaceous siltstone,siltstone developed deformed structure and massive bedding,with scour surface at the bottom,turbidity deposit.Longmaxi upper part of the group is composed of dark gray and gray mudstone intercalated with silty mudstone and thin siltstone.The mudstone has developed horizontal bedding with deformed structures and enveloping bedding.It is a shallow sea shelf with turbidity current deposits.According to FMI,the bottom of Xiaoheba formation is gray mudstone and silty mudstone,which are shallow-sea shelf deposits.