二连盆地阿尔凹陷腾一上段湖底扇沉积特征及油气地质意义

Sedimentary characteristics and petroleum geology of sublacustrine fan of the upper section of the first member of the Tenger Formation in the Aer Sag of the Erlian Basin

综合运用岩心、粒度、测井、地震等资料,识别出二连盆地阿尔凹陷阿尔1井及周边下白垩统腾一上段含油段为湖底扇成因。该湖底扇沉积体以岩心中大量的负载构造、正粒序、块状层理、不完整鲍马序列为其识别标志,在测井曲线上表现为整体低电阻率、高伽马值背景下的指状突起,在地震剖面上则呈透镜状。在地震剖面上识别出了湖底扇中扇及外扇亚相,前者沟道化显著,而后者则不明显。经阿尔凹陷勘探证实,湖底扇中扇的块状砂岩,正粒序砂岩具有较好的物性,孔隙度平均达到16.6%,渗透率平均为282×10-3μm2。该湖底扇毗邻烃源岩,易形成岩性圈闭,油气运移和聚集条件优越,对油气勘探具有重要的意义。

The upper section of the first member of the Lower Cretaceous Tenger Formation in well Aer1 and neighboring area in the Aer Sag of the Erlian Basin is an oil-bearing formation sourced from a sublacustrine fan according to core,grain size,logging and seismic data. This fan is marked by abundant load structures,normally graded bedding,massive bedding,and incomplete Bouma sequences. Well logs show finger shapes on a background of low resistance and high GR values. Seismic profiles are characterized by lenticular shapes. A middle fan with obvious channels and a lower fan without significant channels have been recognized on seismic profiles. Source rocks surround massive sandstones or normally graded sandstones in a sublacustrine fan,with relatively high porosity（ average 16. 6%） and permeability（ average 282×10-3μm2） can be regarded as favorable petroleum reservoir.