【摘要】 乌尔逊凹陷大磨拐河组主要的沉积类型有水下扇、三角洲,砂坝等。水下扇主要分布在大一至大二段,又可进一步分为扇根(包括主沟谷和主沟堤2个微相)、扇中(包括扇中沟道、沟间及扇中前缘3个微相)和扇端。三角洲主要分布在凹陷南部的大二段至大四段和北部的大五段,钻井揭示的前缘相带可以进一步分为水下分流河道、河口砂坝、砂席、远砂坝4个微相。砂坝主要分布在凹陷南部大四段至大五段,砂坝一般为水进层序。更多还原

【Abstract】 Wurxun Depression covers approximately an area of 2350 km~2. The DamoguaiheFormation, an upper Jurassic lacustrine sequence with a thickness of 2000 m is the mainobjective for petroleum exploration in Hailar Basin. The formation can be divided into fivemembers. The main types of sedimentary facies in the Damoguaihe Formation aresubaqueous fan, delta, barrier bar, beach and slope apron, etc. Combining seismicstratigraphy and well logging information, the sedimentary facies are recognized and subdivided. Subaqueous fan deposits, developed on the steep margin from the first memberto the third member, are fan-shaped in plan figure. The external forms are symmetric orasymmetric mounds in strike sections and wedges in dip section. The fan system can be divided into three subfacics which differ from one another in sedimentary features. Theinner-fan deposits, consisting of main channels and main levees, are characteristic ofdebris flows. The mid-fan subfacics include braided channel, interchannel debris flow,and mid-fan front microfacies.Deltas, developed mainly on the gentle margins of the depression, aretongue-shaped in plan figure and wedge-shaped in dip sections. The fluvial sands, channel mouth bars and delta front sheet sands, channel mouth bars and delta front sheetsands are described.Barrier bars are well developed in the upper part of the formation. The transgressivebarrier bars result from reworking of longshore currents and waves. Most delta front sandsare reworked into barrier bars in the transgressive settings.更多还原