海拉尔盆地贝尔凹陷下白垩统南屯组储集层特征

海拉尔盆地是大庆油田较大的含油气盆地之一，贝尔凹陷是盆地内最大的凹陷，属于海拉尔盆地贝尔湖坳陷的二级构造单元，同时也是该盆地最有潜力的勘探地区。其主要储集层为下白垩统南屯组、铜钵庙组砂岩、凝灰质砂砾岩和凝灰岩及基岩风化壳。其中南屯组储集层主要岩石类型包括火山碎屑岩、陆源碎屑岩及少量的火山岩，其储集层主要储集空间类型为粒间孔隙、粒内孔隙、填隙物孔隙、裂缝和溶蚀孔隙。其孔隙结构较差，喉道半径小，分布不集中，分选不好。受沉积相带、埋深压实作用以及次生孔隙的影响，贝尔凹陷储集层物性总体以中低孔、低渗为特征，储集层主要分布于贝西次凹、贝西单斜带、霍多莫尔断鼻带和苏仁诺尔以及苏德尔特断裂带。

Reservoir characteristics of the Lower Cretaceous Nantun Formation in Beier Sag of Hailar Basin

 The Hailar Basin is one of the larger petroliferous basins currently explored by the  Daqing Oilfield Company. The  Beier Sag is the biggest sag in the basin and it is one of the structural units comprising the  Beierhu  Depression in Hailar Basin. The sag is also the most prospective prospecting area. The main reservoirs include the Lower Cretaceous Nantun Formation and Tongbomiao Formation and the rock types are sandstone， tuffaceous glutenite， tuff and base rock weathering  crusts. The main reservoirs consist of sandstone, tuffaceous gravelly sandstones, and tuffs in the Nantun and Tongbomiao Formations, and weathered crust of the basement. The main reservoir rock types in the Lower Cretaceous Nantun Formation include volcanic clastics, siliciclastics and subordinate volcanic rock. Its main porosity types are intergranular pore， intragranular pore， calking pore， fracture pore and dissolution pore. The pore texture is not favorable， throat distribution is not centralized，  throat sorting is not very good， and throat radius is small. Due to the influence of sedimentary facies， compaction and secondary porosity， the main reservoir petrophysics is  characterized by moderate to low porosity， and low permeability. The reservoirs are   distributed in West Beier Subsag， West Beier monocline belt， Huoduomoer faultd nose structure belt， Surennuoer and Sudeerte fracture belts.