| 塔河油田奥陶系岩溶塌陷体结构识别及成因分析 |
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| 引用本文： | 李新华,康志宏,刘洁,杨德彬,汪彦,陈华鑫,贺煜.塔河油田奥陶系岩溶塌陷体结构识别及成因分析[J].现代地质,2021,35(6):1830-1843. |
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| 作者姓名： | 李新华 康志宏 刘洁 杨德彬 汪彦 陈华鑫 贺煜 |
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| 作者单位： | 1.中国石化缝洞型油藏提高采收率重点实验室,新疆 乌鲁木齐 8300112.中国石化西北油田分公司勘探开发研究院,新疆 乌鲁木齐 8300113.中国地质地质学(北京) 能源学院,北京 100083 |
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| 基金项目： | 国家科技重大专项(2016ZX05053);中国石化缝洞型油藏提高采收率重点实验室基金项目 |
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| 摘 要： | 塔河油田奥陶系碳酸盐岩古溶洞塌陷是一种特殊的岩溶型储集体,塌陷作用导致早期洞穴的坍塌、围岩多类型的角砾岩化以及孔隙结构在一定范围上的改造等。通过钻井、岩心、常规测井、FMI 成像测井等技术手段来识别和再现了塌陷体裂纹角砾岩、镶嵌角砾岩、混杂角砾岩和溶洞及其沉积充填物等独特的响应特征。展示了岩溶塌陷体及其上覆地层地震同相轴“下凹”和伴随“串珠”状—杂乱反射的地震结构特征。依据塌陷几何结构的生长指数(EI)、垂向海拔变化(ΔZ)以及宽度(W)等参数定量评价,指出塌陷形成具有多期次性,在下巴楚泥岩段达到峰值。通过实例剖面分析,将塌陷体分为3种类型:(1)早期(表生岩溶期)溶蚀塌陷,常发育多层洞穴垮塌,塌陷带内角砾岩发育,构成了灰岩和混杂角砾与泥质支撑的混杂角砾复杂岩性组合,储集体上下整体连通,具有一定的储集性能;(2)中期(早石炭世)负载塌陷,属于埋藏后塌陷,储集体由缝隙、裂纹角砾岩、镶嵌杂乱角砾岩、富碎屑基质支撑的杂乱角砾岩和洞穴沉积的石英砂岩组成,存在未充填的残余洞穴储集空间;(3)晚期(海西晚期)断控塌陷,海西晚期构造导致的埋藏后的古溶洞塌陷,形成新的“缝隙、镶嵌角砾岩、杂乱角砾和原始溶洞”的塌陷结构,储集性能较好。原始洞穴层、塌陷时间和主控因素三者的相互组合导致了古洞穴塌陷的复杂储集体结构。分析认为负载塌陷和断控塌陷发育有效的储集空间,可作为油气开发有利的潜力目标区。
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| 关 键 词： | 岩溶 塌陷 储集体 奥陶系 塔河油田 塔里木盆地 |
| 收稿时间： | 2021-01-05 |
| 修稿时间： | 2021-05-10 |
Characteristics Identification and Formation of Ordovician Karst Collapse Reservoir Structure in Tahe Oilfield |
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| LI Xinhua,KANG Zhihong,LIU Jie,YANG Debin,WANG Yan,CHEN Huaxin,HE Yu.Characteristics Identification and Formation of Ordovician Karst Collapse Reservoir Structure in Tahe Oilfield[J].Geoscience——Journal of Graduate School,China University of Geosciences,2021,35(6):1830-1843. |
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| Authors: | LI Xinhua KANG Zhihong LIU Jie YANG Debin WANG Yan CHEN Huaxin HE Yu |
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| Institution: | 1. SINOPEC Key Laboratory of Enhanced Oil Recovery for Fractured Vuggy Reservoirs,Urumqi,Xinjiang 830011,China2. Research Institute of Northwest Petroleum Branch, SINOPEC, Urumqi, Xinjiang 830011, China3. School of Energy Resources, China University of Geosciences, Beijing 100083,China |
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| Abstract: | The Ordovician carbonate paleokarst cave collapse in the Tahe oilfield is a special karst-type reservoir, and gave rise to the collapse of early caves, many types of wallrock brecciation, as well as certain transformation of pore structure. In this paper, the unique response characteristics of crackle breccia, mosaic breccia, mixed breccia, karst caves and their sediment fillings have been identified by drilling, coring, 3-D seismic data, conventional logging, and FMI image logging. The seismic configuration characteristics of karst collapse and overlying strata are presented, which consist of a downward-concave seismic event and “string” and chaotic seismic reflection. Collapse geometric parameters, such as the expansion index (EI), vertical relief (ΔZ), and the width (W) are used to quantitatively assess the paleokarst collapse. The results indicate that the collapse formation was multi-stage and reached a peak in the Xiabachu mudstone interval. The collapse can be divided into three types through profile analysis: (1)early epidiagenetic-stage karst collapse, which usually develops multilayer cave collapse. Breccias were developed in the collapse zone, forming a complex mixed breccia lithological assemblage supported by limestone matrix, mixed breccia and mud. The reservoir is connected integrally, which has certain storage capacity; (2)the middle-stage (Early Carboniferous) load collapse can be attributed to post-burial collapse, which is composed of cracks, crackle breccia, mosaic chaotic breccia, clastic matrix-supported chaotic breccia and cave-deposited quartz sandstone. There are some unfilled residual caves reservoirs; (3)Late Hercynian fault-controlled collapse, which was formed by coeval tectonic movement and gave rise to a new collapse structure comprising cracks, mosaic breccia, chaotic breccia and filled caves, with better reservoir property. The combination of original cave layers, collapse time and main control factors may have results in the complex reservoir structure of paleokarst cave collapse. It is considered that load collapse and fault-controlled collapse have developed effective reservoirs, which represent favorable targets for oil and gas development. |
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| Keywords: | karst collapse reservoir Ordovician Tahe oilfield Tarim basin |
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