海拉尔盆地苏德尔特构造带基底裂缝特征及控制因素

摘要

裂缝是海拉尔盆地苏德尔特构造带基底的主要储集空间，其发育规律控制着苏德尔特构造带的油气分布。根据岩芯、测井等资料并结合盆地及其周缘露头观察，对海拉尔盆地火山岩基底储层裂缝特征和控制因素进行研究。结果表明海拉尔盆地苏德尔特构造带基底储层裂缝包括非构造缝（风化缝、溶蚀缝）和构造缝，其中以构造缝为主。裂缝长度变化较大，主要缝宽在0.1～3.0 mm，既有低角度缝也有高角度缝，有效裂缝倾角多为25°～80°。裂缝走向以北东向、近东—西向为主，其次为北西—南东向。裂缝的发育程度主要受基底岩性、剥蚀淋滤作用和构造作用控制，构造作用对全区裂缝的形成和改造具有重要意义。基底裂缝储层分段发育，各段储层裂缝主控因素不同，风化作用主要影响浅层裂缝发育；淋滤作用影响中层裂缝发育；构造作用控制深层裂缝发育。深层致密带储层是苏德尔特构造带深层油气藏勘探的重点目标区，主要发育在盆地基底深大断裂附近或是基底内幕构造应力转化带。研究对于海拉尔盆地基底内幕的油气勘探具有指导借鉴意义。%Objectives:Fracture is the dominant reservoir for Sudeert structural belt,Hailar (Hailaer) basin.Its development directly controls the oil and gas distribution of Sudeert structural belt. Methods:The log information including log analysis,data of geology,mud log as well as production test were collected from Daqing Oil Ltd.Company of China.We described and recorded about 300m core data from 10 wells,and shot about 200 pictures to record the typical fracture characteristics.Fine structure and stratigraphic interpretation had been conducted for the Budate formation in Sudeert structural belt by demarcation on 3 D seismic profiles covering an area of 150 km2 . Results and conclusions:We conclude that fractures in Sudeert structural belt are in three forms,namely structural fracture,weathered fracture and dissolution fracture,of which structural fracture is the dominant form. The length of fractures is 1 ~7mm.There are fractures of both low and high angle,the effective fracture angle being 25°~80°.The fracture strike is mainly in North—East and near East—West direction,then NW—SE direction.The fracture development is determined by basement lithology,tectonic forces and stratigraphic erosion. The tectonic setting has a significant influence on fracture formation and transformation in the study area.Basement reservoir fractures distribute vertically in segments,and the main governing factors are different:weathering influences development of fractures on the top;Leaching effect influences development of fractures in the middle;Deep fault influences development of deep fractures.Deep fracture reservoir develops near the deep fault or transformation zone of tectonic stress in the bottom of basin.The deep reservoir is the target zone for oil and gas exploration.The research had a guiding significance in the study of oil and gas exploration in Hailar basin.