下刚果盆地A区块中新统深水沉积体系特征

下刚果盆地中新统主要的沉积类型为深水重力流沉积。通过对钻井与测井资料的分析，结合高分辨率三维地震特征的研究，揭示了下刚果盆地西南部地区中新统深水沉积体系与层序的发育特征。A区块中新统可识别出7个三级层序(SQ1—SQ7)，层序格架下发育块体搬运沉积、水道、堤岸、朵体、废弃水道、决口扇及深海泥质沉积7类沉积单元。各层序格架下重力流发育特征和规模不尽相同，其中SQ1—SQ2和SQ4—SQ5沉积时期重力流沉积规模较小，发育小型高弯度重力流水道和堤岸沉积；SQ3和SQ6—SQ7沉积时期重力流沉积规模较大，发育大型复合重力流水道、朵体和堤岸沉积。综合研究区深水沉积单元的发育特征，建立了该区深水重力流沉积模式，即块体搬运沉积发育在近陆坡区域，向前依次发育近源端的水道-堤岸复合体和决口扇沉积，水道高弯度地区的废弃水道以及水道末端的朵体沉积。这个沉积模式为该地区下一步的深水油气勘探提供了理论依据。

Characterization of deep water sedimentary system in the Miocene of Block A in Lower Congo Basin

Sedimentary types in the Miocene of Lower Congo Basin is of dominantly deep water gravity flow.Analyses of drilling and logging data combined with study of high-resolution 3D seismic attributes reveal characteristics of the deep water sedimentary system and sequence of southwestern lower Congo Basin.About 7 third-order sequences can be recognized from the Miocene of Block A:massive transportation,water channels,levees,lobes,abandoned water channels,flood fans and deep sea mud under their respective sequence frameworks.Features and scales of gravity flow under these frameworks vary greatly:small-scale highly-bent gravity flow channels and levees were developed in the less intensive sedimentation of SQ1-SQ2 and SQ4-SQ5 and massive complex gravity flow channels,lobes and levees were developed during the large-scale deposition of SQ3 and SQ6-SQ7.An integrated development characterization of the units was performed to establish the sedimentary model in the area:the massive transportation occurring near continental slope,water channel-levee complexes and flood fans near provenance,and abundant water channels in highly-bent area and lobes at the end of water channels.The modal may provide guidance for further deep oil and gas exploration in the area.