鄂尔多斯盆地奥陶系马家沟组四段沉积特征及其控储效应  

Sedimentary characteristics and reservoir controlling effect of the Member 4 of Ordovician Majiagou Formation in Ordos Basin

作　　者：吴东旭 喻建[3] 周进高 吴兴宁 于洲 丁振纯 王少依 李维岭 蔡君 Wu Dong-Xu;Yu Jian;Zhou Jin-Gao;Wu Xing-Ning;Yu Zhou;Ding Zhen-Chun;Wang Shao-Yi;Li Wei-Ling;Cai Jun(Petro China Hangzhou Research Institute of Geology,Hangzhou 310023,China;Key Laboratory of Carbonate Reservoir,CNPC,Hangzhou 310023,China;Changqing Oilfield Company,Petro China,Xi'an 710018,China)

机构地区：[1]中国石油杭州地质研究院,浙江杭州310023 [2]中国石油天然气集团有限公司碳酸盐岩储层重点实验室,浙江杭州310023 [3]中国石油长庆油田分公司,陕西西安710018

出　　处：《古地理学报》2021年第6期1140-1157,共18页Journal of Palaeogeography：Chinese Edition

基　　金：国家科技重大专项(编号:2016ZX05004-002,2017ZX05008-005);中国石油科技重大专项(编号:2018A-0103)联合资助。

摘　　要：鄂尔多斯盆地奥陶系马家沟组四段(简称"马四段")是下古生界天然气风险勘探的重点层位。文中基于岩心、薄片观察,结合地层对比、沉积结构描述等,并运用岩石结构组分测井解释和井震结合古地貌恢复等手段,对鄂尔多斯盆地马四段沉积时期古地貌、沉积特征和储集层展布进行了详细分析。结果表明:(1)受控于沉积期隆坳相间的古地貌格局,马四段发育大量台地内丘滩微相,其易于发生准同生溶蚀和白云石化作用,是储集层发育的有利相带;(2)马四段储集层以(藻)砂屑白云岩和粉—细晶白云岩为主,储集空间主要为粒间孔、晶间孔、溶蚀孔等;(3)纵向上,储集层主要分布于马四_(2)亚段和马四_(1)亚段;平面上,马四段储集层主要分布于台地内低凸起带和台缘带;(4)储集层的发育受控于3个因素,其中古隆起部位发育的有效丘滩体是储集层形成的物质基础,高频层序控制的准同生溶蚀作用是储集层形成的关键,白云石化是储集层后期保存的重要因素。马四段沉积时期碳酸盐岩台地内隆坳相间的古地貌控制了丘滩相带和白云岩储集层的展布,这一新认识为鄂尔多斯盆地下古生界天然气勘探提供了有力支撑,也为碳酸盐岩台地沉积储集层的研究提供了新思路。The Member 4 of Majiagou Formation(i.e.Ma_(4) Member)of Ordovician in the Ordos Ba-sin is the key target for risk exploration of natural gas in Lower Paleozoic.Based on the observation of core and thin section,the stratigraphic correlation,sedimentary structure description,well logging interpreta-tion of rock structure and composition,and the combined well-seismic method for palaeogeomorphologic restoration,the palaeogeomorphology,sedimentary features and reservoir distribution of the Member 4 of Majiagou Formation in the Ordos Basin were analyzed in detail.Results show that:(1)Controlled by the palaeogeomorphologic pattern of uplift and depression in the depositional period,a lot of mound and bank microfacies developed in the Ma_(4) Member and the penecontemporaneous dissolution and dolomitization were prone to occur,making it become the favorable sedimentary facies belt for reservoir development.(2)The reservoir of Ma_(4) Member is mainly composed of(algal)arenaceous dolostone and silt-fine grain dolostone,and the reservoir space is mainly characterized as intergranular pores,intercrystal pores and dissolution pores.(3)The reservoirs are mainly distributed in Ma_(4)^(1) and Ma_(4)^(2) submembers,which are lo-cated at the low uplift belt in the platform and the platform margin belt.(4)The development of the reser-voir is controlled by three factors.The mound-bank body developed in the palaeo-uplift is the material ba-sis.The penecontemporaneous dissolution controlled by the high frequency sequence is the key to the for-mation of the reservoir,and dolomitization is an important factor for the preservation of the reservoir in the later period.The palaeogeomorphology of alternating uplift and depression in the carbonate platform during the Ma4depositional period controlled the distribution of mound-bank facies and dolomite reservoirs,which provided a strong support for gas exploration in the Lower Paleozoic,and also provides a new idea for the study of the sedimentary reservoir in the carbonate platform.

关 键 词：沉积微相 白云岩储集层 古地貌 颗粒滩 准同生溶蚀 马家沟组 鄂尔多斯盆地 

分 类 号：P618.130.21[天文地球—矿床学]