渤中凹陷北部古近系底部不整合发育特征及其与油气成藏关系

不整合是油气输导体系中的重要组成部分，也是油气成藏的有利场所。以渤海湾盆地渤中凹陷北部为例，综合利用三维地震资料、钻测井资料和岩心薄片资料，对古近系底部不整合发育特征及其对油气成藏影响进行分析。结果表明，渤中凹陷北部古近系底部不整合包括5种接触类型和7种结构类型。不整合通道类型划分为双运移通道I型、单运移通道Ⅱ1型和Ⅱ2型以及封堵型Ⅲ型，单运移通道Ⅱ1型是研究区主要的不整合油气成藏类型。运聚类型包括侧向型、圈闭+侧向型、垂向+侧向型和封堵型4种。不整合之上砂岩输导油气的能力与砂岩微观特征及裂缝倾角相关，半风化岩层对油气的输导储集能力受控于原始孔渗良好且不易形成风化黏土层的火山岩。

Development characteristics of the unconformity on the bottom Paleogene in the northern Bozhong Sag and its relationship with hydrocarbon accumulation

Unconformity is an important part of hydrocarbon migration system and a favorable place for hydrocarbon accumulation. Taking the northern Bozhong Sag in Bohai Bay Basin as an example, we analyzed the characteristics of unconformity development on bottom Paleogene and its influence on hydrocarbon accumulation comprehensively by using the data from 3D seismic, drilling and logging, and core thin-section. Results show that there are five contact types and seven structural types of the Paleogene bottom unconformity in the northern Bozhong Sag. Unconformity channel types can be divided into double migration channel type Ⅰ, single migration channel type Ⅱ1 and Ⅱ2 and plugging type Ⅲ. The single migration channel type Ⅱ1 is the main type of unconformity hydrocarbon accumulation in the study area. The migration and accumulation types include lateral type, trap and lateral type, vertical and lateral type, and plugging type. The hydrocarbon migration capacity of sandstone above the unconformity is related to the microscopic characteristics of sandstone and the dip angle of fracture. The hydrocarbon migration and storage capacity of semi-weathered rock strata are controlled by the volcanic rocks with good original porosity and permeability and difficult to form weathered clay layer.