赤水及邻区燕山期古构造特征与油气聚集关系

Paleostructure characteristics of Yanshan stage and its relationship with hydrocarbon accumulation in Chishui and neighboring area

(1.成都理工大学油气藏地质与开发工程国家重点实验室，四川成都610059；2.中国石油化工股份有限公司南方勘探开发分公司研究院，云南昆明650200)

State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Chengdu University of Technology, Chengdu 610059, China

为了弄清赤水及邻区燕山期古构造特征与油气聚集的关系，首先应用钻井资料、地震资料、部分野外露头实测资料，以陆相碎屑岩地层的5个界面为研究对象，采用“标志层”拉平技术——标志层厚度法恢复了主要目的层在燕山期的古构造面貌，查清了古隆起的分布范围，编制了古构造图，并分析了古构造的发育情况和演化特征。须家河底面的古构造总体上表现为“三隆两凹”的构造格局；须家河顶面的古构造主要表现为被“X”形的古凹陷分割的4个古隆起平台；东岳庙顶面和凉高山顶面的古构造相似，具有继承性发育的特点。大致以现今的官渡构造带为界，工区东部古构造形态相对较简单，凸起和凹陷的幅度均不大，中西部古构造相对较发育，表现为多凸多凹，凸凹相间的古构造格局。结合前人对区内生烃史和烃源岩演化史的研究结果，分析了古构造与油气聚集的关系，认为燕山期古隆起与下伏海相烃源岩和上三叠统烃源岩的生烃高峰期相匹配，是油气运聚的有利指向区。

The study focuses on the relationship between paleostructure characteristics and hydrocarbon accumulation in ChiShui and neighboring area during Yanshan stage. Firstly, taking the five interfaces of continental clastic formation as target, we use the‘marker bed’ flattening technology, drilling data, seismic data and part of field crop actual data to restore the palaeostructure of intended intervals in Yanshan stage, identify the distribution of paleohigh, draw the palaeostructure map, and analyze the development and evolution features of palaeostructure. The palaeostructure at the bottom of Xujiahe displays ‘three uplifts and two depressions’ divided by X-shaped paleo-depression into four paleohigh platforms. The paleostructures on the top of Dongyuemiao and Liaogao Mountain are similar in the feature of successional development with the Guandu structure belt being its boundary. The paleostructure shape in eastern working area is relatively simple and both the relief of uplifts and the depressions are small in scale. The paleostructure in the middle and the west is relatively well developed, showing a paleostructure pattern of numerous and alternative uplifts and depressions. Then, combined with the former research results of hydrocarbon-generation history and hydrocarbon source rock evolution history in this area, the relationship of paleostructure and hydrocarbon accumulation is analyzed, indicating that the paleohigh of Yanshan stage well matches the hydrocarbon-generated fastigium of underlying marine and Upper Triassic hydrocarbon source rock and so is the beneficial zone of hydrocarbon migration and accumulation.