川南古蔺地区仁页1井五峰组——龙马溪组生物地层及成藏特征  

BIOSTRATIGRAPHY AND RESERVOIR CHARACTERISTICS OF THE WUFENG-LONGMAXI FORMATIONS SHALE IN WELL RENYE-1 OF GULIN AREA,SOUTHERN SICHUAN PROVINCE

作　　者：何贵松 HE Gui Song(Research Institute of Exploration and Development,East China Branch of SINOPEC,Nanjing 210011)

机构地区：[1]中国石油化工股份有限公司华东油气分公司勘探开发研究院,江苏南京210011

出　　处：《地层学杂志》2021年第2期142-150,共9页Journal of Stratigraphy

基　　金：国家科技重大专项(2016ZX05061);中国石化科技部项目(P19017-3、P20059-6)共同资助。

摘　　要：四川盆地南部古蔺地区(以下简称川南古蔺地区)处于盆缘构造转折部位,靠近黔中隆起,仁页1井钻探揭示该区发育五峰组—龙马溪组下部黑色页岩,笔石种类和含量丰富。为了揭示该区笔石生物地层特征及其对页岩气成藏的影响,根据仁页1井岩芯资料,本研究开展笔石生物地层划分,建立了该区凯迪期—埃隆早期笔石生物地层序列,并与四川盆地及周缘的主要页岩气田进行生物地层对比,深化该区页岩气勘探潜力认识。研究结果表明:(1)仁页1井五峰组—龙马溪组下部地层,涵盖了从凯迪阶上部的Dicellograptuscomplexus带(WF2带)至埃隆阶下部的Demirastrites triangulatus带(LM6带),共9个完整连续的笔石生物带。(2)古蔺地区与主要页岩气田的生物地层具有较好可比性,但该区受黔中隆起的影响较大,具体表现为:凯迪阶,黑色页岩厚度较薄;赫南特阶,海平面下降较快,海水较浅,形成了富含Hirnantia动物群化石的观音桥段介壳灰岩;赫南特阶上部—鲁丹阶,水体相对较浅,同时沉积速率较慢,形成的LM1—LM5带黑色页岩相对较薄。(3)古蔺地区WF2—LM5带黑色页岩具有笔石含量丰富、自然伽马值高、斑脱岩层密集的特征,指示古生产力高,利于有机质富集和页岩气生成;同时石英等脆性矿物含量较高,利于压裂改造,具有较好的页岩气成藏条件。The Gulin area in southern Sichuan Basin is located in basinal margin and a tectonic transitional zone,near the Central Guizhou Uplift during the Ordovician-Silurian transition.The drill core of Well Renye-1 reveals that black shale is well developed in the lower part of the Wufeng and Longmaxi formations in this area,in which graptolites are abundant and highly diverse.In order to reveal the characteristics of the graptolite biostratigraphy and its influence on the formation of shale gas reservoirs in this area,a graptolites biostratigraphic study is carried out by using the core data of Renye-1.As a result,a largely continuous graptolite biostratigraphic sequence is established,spanning from the late Katian to the early Aeronian.A comparison of biostratigraphic scheme of the Gulin Area with those of main shale gas fields in the Sichuan Basin and its adjacent areas is conducted,aiming to deepen the understanding of shale gas exploration potential in this area.The results show that:(1)The lower strata of the Wufeng and Longmaxi formations in Renye-1 contain 9 continuous graptolite zones spanning 4 stages,from Dicellograptus complexus Zone(WF2)in the upper part of Katian stage to the Demirastrites triangulatus Zone(LM6)in the lower part of Aeronian.(2)The biostratigraphic sequence in the Gulin area is comparable to those of the main shale gas fields in the Sichuan Basin,while the area is greatly affected by Qianzhong uplift.In the Gulin Area,the black shale of the Katian stage is thinner,and in the Hirnantian stage the sea level dropped quickly and the sea water depth became shallower,which formed the mesoscale limestone of Guanyinqiao Bed yielding rich fossils of Hirnantia fauna.In the upper part of the Hirnantian-Rhuddanian stages,the depth of the water body was relatively shallower than elsewhere of the Sichuan Basin,and the deposition rate was relatively lower,resulting in the low thickness of the black shale of the LM1-LM5 zones.(3)The black shale of the WF2-LM5 zones in the Gulin Area shows the characteristi

关 键 词：仁页1井 笔石 页岩气 五峰组—龙马溪组 四川盆地 

分 类 号：P534.42[天文地球—古生物学与地层学] P534.43[天文地球—地质学]