山东博兴地区压力系统分析及油气成藏动力学机制

The pressure systems and dynamic mechanisms for oil and gas accumulation in the Boxing region,Shandong

关键词:  博兴  异常压力  油气成藏  动力学机制  山东

Key words:  Boxing  abnormal pressure  oil and gas accumulation  dynamic mechanism  Shandong

摘要:

博兴地区沙三段、沙四段油藏普遍具有异常高压。本文利用泥岩声波时差资料研究了地层压力在单井、剖面和平面上的分布特征,异常高压带在各井出现深度大致在2100～ 2500m左右,层位上与沙三段大套泥岩出现有关,剩余流体压力剖面上具有分带性,明显受构造位置、沙三段泥岩以及断层等因素控制,平面上高剩余流体压力值与洼陷区相伴生,且构造陡坡带剩余流体压力梯度值较大,缓坡带剩余流体压力梯度值较小,油气基本聚集于异常压力系统中的相对低压区和常压区。根据异常压力在平面上的分布特点以及油气藏形成特征,将博兴地区的成藏动力学机制划分为自源封闭型成藏动力学机制和它源开放型成藏动力学机制两种类型。

Abstract:

The abnormal high pressures appear in the oil and gas pools from the third and fourth members of the Shahejie Formation in the Boxing region,Shandong.In the light of the distribution of stratigraphic pressures in a single well,section and plan with the aid of the acoustic logs for mudstone,the abnormal high-pressure zones in individual wells are delineated at the depth of about 2100-2500 m,horizontally related to the occurrence of mudstone in the third member of the Shahejie Formation.The residual fluid pressures are zoned,and constrained by tectonic setting,mudstone from the third member of the Shahejie Formation and faults.The high residual fluid pressure values occur in the depressions.The residual fluid pressure gradients are higher in structurally steep slope zones,and lower in the ramp zones.The oil and gas are often accumulated in the relatively low-pressure areas and normal pressure areas within the abnormal systems.Two types of dynamic mechanisms for oil and gas accumulation have been distinguished for the Boxing region: authigenic enclosed type and allothigenic open type.