渤海湾盆地石炭-二叠纪沉积作用与储层形成

PERMO-CARBONIFEROUS SEDIMENTATION AND RESERVOIRING IN THE BOHAI BAY BASIN

随着浅部油气资源的逐步查明,目前的油气勘探方向开始向深部转移。为此,从沉积控制方面对渤海湾盆地深部储层展布及其物性特征进行了研究,以期为深部油气勘探提供地质依据。应用录井、测井及岩心资料,测定了孔隙度、渗透率等物性参数,查明了渤海湾盆地石炭—二叠系各地层组的骨架砂岩展布特征及其物性特征;应用相比法编图对渤海湾盆地石炭纪、二叠纪岩相古地理进行了恢复,研究了沉积相对储层及其物性特征的控制作用。结果表明:该区下石盒子组和上石盒子组是形成油气藏最有利的储层;河流体系的边滩相和心滩相对砂体的控制作用最强,其次为三角洲平原分流河道相和潮坪相;物性从好到差依次为:曲流河砂体—三角洲砂体—障壁岛砂体—潮坪砂体。

The focus of oil and gas exploration in the Bohai Bay basin has been turned to the deep plays at present as the shallow ones have been basically proved.Studies are carried out on the distribution and physical properties of the deep reservoirs in the Bohai Bay basin in respect of sedimentary control factors,so as to lay a geologic foundation for deep oil and gas exploration.Various log and core data are used to estimate the petrophysical parameters such as porosity and permeability,and to define the distribution and petrophysical properties of the framework sandbodies in each formations of the Permo-Carboniferous in the Bohai Bay basin.Analogy mapping method is used to reconstruct the Carboniferous and Permian lithofacies palaeogeography in the Bohai Bay basin,and to study the controlling effects of sedimentary facies on reservoirs and their petrophysical properties.The following understandings are obtained.The reservoirs in the Lower Shihezi and Upper Shihezi formations are most favorable for hydrocarbon accumulation.The sandbodies are controlled most strongly by the marginal bank facies and channel bar facies of fluvial systems,followed by distributary channel facies of delta plain and tidal flat facies.The poroperm characteristics of the reservoirs get poorer progressively in the sequence of meander river sandbody-delta sandbody-varrier bar sandbody-tidal flat sandbody.