渝西大足区块五峰组-龙马溪组古地貌特征及其对优质页岩发育的影响  

Paleogeomorphic characteristics of Wufeng-Longmaxi formation and its influence on development of high-quality shale in Dazu area,Western Chongqing

作　　者：蒋婵 张海杰 周亚东 干华文 蒲俊伟 蒋裕强[3] 付永红[3] 谷一凡 李杪 王占磊[3] 尹兴平 JIANG Chan;ZHANG Haijie;ZHOU Yadong;GAN Huawen;PU Junwei;JIANG Yuqiang;FU Yonghong;GU Yifan;LI Miao;WANG Zhanlei;YIN Xingping(Exploration Division,PetroChina Southwest Oil and Gas Field Company,Chengdu 610051,China;Chongqing Shale Gas Exploration and Development Co.Ltd.,Chongqing 401120,China;School of Geoscience and Technology,Southwest Petroleum University,Chengdu 610500,China;Lunnan Oil and Gas Development Department of PetroChina Tarim Oilfield Company,Korla 841000,China)

机构地区：[1]中石油西南油气田分公司勘探事业部,四川成都610051 [2]重庆页岩气勘探开发有限责任公司,重庆401120 [3]西南石油大学地球科学与技术学院,四川成都610500 [4]中石油塔里木油田分公司轮南油气开发部,新疆库尔勒841000

出　　处：《中南大学学报（自然科学版）》2022年第9期3628-3640,共13页Journal of Central South University:Science and Technology

基　　金：中石油−西南石油大学创新联合体项目(2020CX020104)。

摘　　要：为了提升渝西大足区块优质页岩厚度预测精度,明确优质页岩发育的影响因素,首先,本文依据地震资料、钻井数据和岩相古地理格局,识别地层沉积填平补齐界面;其次,采用印模法与波形分类相结合的方法,精细刻画龙马溪组下部黑色页岩段的沉积古地貌;最后,分析不同古地貌页岩储层的厚度、矿物组成、粒度、有机质富集方式、纹层结构形式、储集空间和含气性等特征。研究结果表明:研究区五峰组—龙马溪组呈现“南低北高”古地貌的总体格局,由南向北表现为“一洼地和两排古凸起”的特点;古地貌相对低洼地区w(U)/w(TH),w(V)/w(Cr)和w(Ni)/w(Co)最大,有利于富有机质页岩的沉积和保存;古地貌低地区纹层结构以富有机质纹层、含有机质纹层、含有机质+粉砂质纹层为主,古地貌高地发育更多的粉砂质纹层;在扫描电镜观察下古地貌低的页岩储层有机质具有连片分布的特点,有机质内孔隙发育,多为圆形,“孔连孔”现象明显,有利于页岩气储集,含气性高,储层品质较好。In order to improve the prediction accuracy of shale thickness and clarify the influencing factors of high-quality shale in Dazu area,Western Chongqing,firstly,seismic data,drilling data and lithofacies paleogeographic pattern were employed and the stratigraphic sedimentary filling and filling interface were identified.Secondly,the sedimentary palaeogeomorphology of the black shale section in the lower part of Longmaxi formation was finely characterized by the combination of impression method and waveform classification.Finally,the thickness,mineral composition,grain size,organic matter enrichment mode,laminar structure,reservoir space and gas bearing characteristics of shale reservoirs with different paleogeomorphology were analyzed.The results show that the overall pattern of paleogeomorphology of the Wufeng—Longmaxi formation in study area is the"South Low and North High".From the south to the north,the ancient landform is characterized by"1 depression and 2-row ancient uplift".The values of w(U)/w(TH),w(V)/w(Cr)and w(Ni)/w(Co)are the largest in the relatively low-lying areas of paleogeomorphology,which is conducive to the deposition and preservation of organic rich shale.The laminar structure of shale reservoir in the low paleogeomorphic area are mainly rich in organic laminae,containing organic laminae and containing organic+silty laminae,while more silty laminae is developed in the high paleogeomorphic area.The shale reservoir with low paleogeomorphology has a large distribution area of organic matter under the observation of SEM,circular organic pores in the organic matter are developed well and the phenomenon of"pore to pore"is obvious,which is conducive to shale gas reservoir with high gas content and good reservoir quality.

关 键 词：页岩 龙马溪组 古地貌 储层 影响因素 

分 类 号：TE122.2[石油与天然气工程—油气勘探]