湖底扇沉积模式及地震响应特征——以二连盆地乌里雅斯太凹陷下白垩统为例  

DEPOSITIONAL MODEL AND SEISMIC RESPONSE CHARACTERISTICS OF THE SUBLACUSTRINE FAN --TAKING LOWER CRETACEOUS OF WULIYASTAI SAG IN ERLIAN BASIN AS EXAMPLE

作　　者：邓毅林[1] 王天琦[1] 曹正林[1] 裴明利[1] 贾义蓉[1] 赵伟[1] 

机构地区：[1]中国石油勘探开发研究院西北分院,甘肃兰州730020

出　　处：《大庆石油地质与开发》2010年第5期35-42,共8页Petroleum Geology & Oilfield Development in Daqing

基　　金：国家重点基础研究发展计划＂973＂项目（2007CB209604）资助.

摘　　要：二连盆地乌里雅斯太凹陷下白垩统发育的湖底扇砂砾岩体是岩性油藏勘探的重要领域,扇体分布规模小、相变快,勘探难度大.通过对岩心、测井等地质资料分析,建立了湖底扇砂砾岩体沉积模式.分析认为湖底扇由补给水道、内扇、中扇和外扇4部分组成,发育补给水道、內扇主沟道、中扇辫状沟道和外扇浊积水道等主要微相类型.其中内扇、中扇和外扇为湖底扇的主体,分布在同沉积断层的下降盘,为半深湖-深湖沉积 补给水道是湖底扇的＂根＂,分布在同沉积断层的上升盘,为滨浅湖沉积.指出了足够的可容纳空间和持续的物源补给是形成厚层湖底扇的2个重要条件,同沉积断裂的下降盘是湖底扇发育的有利部位.应用精细合成记录对湖底扇砂砾岩体进行了井-震联合标定,发现湖底扇在地震剖面上整体表现为 ＂透镜状＂、＂楔状＂、＂丘状＂或＂梭状＂外形特征,扇体内部表现为杂乱反射或无反射特征.应用湖底扇沉积模式、分布规律以及在地震上的响应特征在二连盆地乌里雅斯太凹陷发现多个岩性油藏,取得了良好的勘探效益.The glutinite body of the well-developed Low-Cretaceous sublacustrine fan in Wuliyastai Sag of Erlian Basin is one of the most important fields of lithologic oil reservoir exploration, but it is characterized by small scale, fast facies change and rather great exploration difficulty. Based on the geological analyses of the cores, well logs and so on, the depositional model of sublacustrine-fan glutinite body is established. The above analyses show that the sublacustrine fan is composed of feeder ehannel, inner fan, middle fan and outer fan, and furthermore the fan can be divided into feeder channel, main channel in inner fan, braided channel in middle fan, turbidite channel in outer fan micro-faeieses and so forth. Among the above, Inner fan, middle fan and outer fan are the maim parties of sublacustrine fan and located on the downthrow wall of contemporaneous fault and belong to half-deep lake sedimentation; feeder channel is the ＂root＂ of sublacustrine fan located on the upthrow wall of contemporaneous fault and belongs to shallow lake sedimentation. Enough accommodation space and continuous supply of deposit are determined to be the two key factors of forming the heavy layer of sublacustrine fan, and moreover the downthrow wall-of contemporaneous fault is the favorable zone for the development of the sublacustrine fan. The well-seismic commingled calibration is conducted for the glutinite body of the sublacustrine fan by applying elaborate synthetic traces. It is discovered that the seismic sections of the sublacustrine fan are generally characterized by lens, wedge, mound and Spindle shapes, and the interior of the fan displays either chaotic seismic reflection or no reflectance signature. With the help of the depositional models of the sublacustrine fan, distribution laws and the seismic response characteristics, multiple lithologic oil pools are discovered in the Wuliyastai Sag of Erlian Basin, and in the end the good exploration benefits are obtained.

关 键 词：湖底扇 沉积模式 反射特征 坡折带 岩性油藏 乌里雅斯太凹陷 二连盆地 

分 类 号：TE121.3[石油与天然气工程—油气勘探]