【摘要】 塔中地区西北部石炭系已开发TZ10、TZ40等多个海相碎屑岩油藏,CⅢ油组(石炭系III油组)含砾砂岩段为其主要的产油层段。通过岩心观察、分析化验资料、测井及地震资料等对含砾砂岩段的沉积相类型进行了研究。分析结果表明,研究区石炭系含砾砂岩段主要为细砂岩、含砾细砂岩,形成多期相互叠置的正韵律砂体,砂岩岩石类型以岩屑质石英砂岩、岩屑砂岩为主,成熟度中等;发育冲刷面、滞留沉积、平行层理、交错层理等层理构造;砂岩粒度概率曲线以2段式为主,悬浮总体含量较高;含砾砂岩段灰色泥岩、褐色泥岩均有发育;泥岩微量元素反映出淡水、咸水古盐度特征;测井形态组合、三维地震属性均显示河道沉积特征。结合区域地质背景,认为研究区CⅢ油组含砾砂岩段为辫状河三角洲沉积,发育三角洲平原的分支河道、越岸沉积以及三角洲前缘的水下分支河道、支流间湾、河口砂坝及席状砂等多种微相类型。辫状河三角洲河道的频繁侧向迁移垂向上形成了砂体的多期叠置,平面上形成了砂体的大面积分布,成为良好的油气储集体,寻找以河道砂体为主的岩性地层油藏是滚动勘探开发的主要目标。更多还原

【Abstract】 In the northwest region of Tazhong area,a number of oil fields have been developed in the Carboniferous marine clastic reservoirs,including Tazhong 10 and Tazhong 40 oil fields,with the conglomeratic sandstone member in CⅢ oil group(Carboniferous Ⅲ oil group) as one of their major oil-producing layers.In order to study the sedimentary facies of conglomeratic sandstone member,an integrated analysis including cores,well logging,seismic data and laboratory data has been performed.According to the analytical result,the conglomeratic sandstone member is composed of multistage superimposed sand bodies in positive rhythm,formed by fine and pebbly fine sandstone.Its rock type is dominated by lithic quartzite and litharenite with moderate maturity.Sedimentary structures such as scour surfaces,lag deposits,parallel bedding and cross bedding can be found.The sandstone grain size probability curve is mainly in the two-segment pattern,featuring large content of suspension population.Both grey and brown mudstones are developed,and the trace elements in mudstones reflect the palaeosalinity of fresh water and salt water.Both logging curves combination pattern and 3D seismic attributes display the characteristics of channel deposit.Referring to the regional geologic background,it is considered that the conglomeratic sandstone member of CⅢ oil group in the study area was braided river delta deposits,and it developed microfacies such as braided channel and overbank deposits in the delta plain subfacies,as well as underwater distributary channel,interdistributary bay,river mouth bar,sheet sand deposits in the delta front subfacies.The frequent lateral migration of braided channels resulted in the multistage superimposition of sand bodies in the vertical direction and wide distribution on the plane,making them favorable reservoirs.Therefore,looking for lithologic-stratigraphic reservoirs in the channel sand bodies should be the main target for progressive exploration and development.更多还原