渤中凹陷油气运移优势通道及有利区预测

PREDICTION OF DOMINANT MIGRATION PATHWAYS AND FAVORABLE EXPLORATION ZONES IN BOZHONG DEPRESSION

渤中凹陷油气分布规律不清,制约着勘探方向的选择,亟待开展与油气分布密切相关的优势通道的研究。根据级差优势、分隔优势、流压优势和流向优势4种优势通道的基本模式,采用单因素叠加和多信息叠合两种方法,对渤中凹陷油气运移优势通道进行了系统分析,确定出分别自凹陷中心向渤南低凸起、石臼坨凸起、沙垒田凸起和渤东低凸起北侧的4个优势通道方向。结合烃源岩展布及油气藏特征,总结出两种有利的油气运聚成藏模式,分别为沙河街组自生自储和优势通道输导-盖层完整的圈闭聚集成藏模式。综合分析认为,渤南低凸起、石臼坨凸起和沙垒田凸起多种优势通道共存,且储集砂体发育,圈闭类型多样,将是有利的勘探区带,区带内盖层完整的圈闭为有利的勘探目标。

Oil and gas distribution is not clear in Bozhong Depression.This restricts the choice of exploration direction.So the dominant migration pathway researches which are closely related to oil and gas distribution are to be carried out urgently.According to the four basic dominant migration patterns:the separation advantage,level difference advantage,flowing pressure advantage and flowing direction advantage,the dominant pathway of hydrocarbon migration of Baozhong Depression is analyzed systematically by using single-element coupling analysis method and multi-element superposition analysis method.As a result,four dominant pathway directions are summarized:from the center of depression to Bonan Low Uplift,Shijiutuo Uplift,Shaleitian Uplift and North of Bodong Low Uplift.Compared with the distribution of source rocks and reservoir characteristics,two kinds of favorable hydrocarbon migration-accumulation reservoir models are summarized.They are respectively self-generation and self-preservation in Shahejie Formation and dominant pathway-cap rock traps.Many kinds of dominant pathways are believed to coexist among Bonan Low Uplift,Shijiutuo Uplift and Shaleitian Uplift according to the comprehensive analysis.Besides,sand bodies are well developed,and there are also various types of traps,making them favorable exploration zones.Traps with complete cap rocks in those zones are favorable exploration targets.