巴布亚盆地侏罗系陆架边缘三角洲沉积特征及其油气勘探方向

为明确巴布亚盆地主要的含油气系统发育层段——侏罗系的沉积特征及其与油气勘探的关系,在分析前人研究成果、沉积背景与古物源的基础上,通过地震相、测井相、岩心相"三相"联合分析及与周边的布劳斯盆地的类比,识别了沉积微相类型,刻画了沉积体系的纵横向展布特征;通过不同沉积相带生烃指标、储层物性参数对比,明确了有利的烃源岩与储层发...

Sedimentary characteristics of the Jurassic shelf-edge delta and oil and gas exploration in the Papuan Basin

In order to ascertain the sedimentary characteristics of the Jurassic and their relationships with oil and gas exploration in the Papuan basin, on the basis of previous studies of the sedimentary background and paleosource in the basin, we performed joint analyses of seismic, logging and core facies in comparisons with the surrounding Browse basin, from which we identified microfacies and described the vertical and horizontal spreads of the basin’s sedimentary systems. Then by comparing the hydrocarbon indices and reservoir physical properties of different sedimentary deposition zones, we defined the favorable source rock and reservoir developmental areas to guide oil and gas exploration. The results show that (1) the Papuan basin featured broad and gentle paleogeomorphology during the Jurassic of the Mesozoic era sloping downward from SW to NE. The main provenance was from the Australia paleocontinents and the peripheral bulge provided local material sources. The Jurassic Formation deposited thick passive continental margin delta sediment, and the microfacies were distributary channels, underwater channels, mouth bars and inter-distributary channels. Its sedimentary characteristics were similar to that of the Plover group of the Jurassic Browse basin also in the northern edge of Australia. (2) The dominant components of the delta came from the southwest, with four delta phases developing vertically in succession through two major regressive and transgressive cycles dominated by an ascending half cycle. The Magobu formation of the middle-lower Jurassic was dominated by a progradational stacking sequence and had sufficient provenance and strong hydrodynamic force, while the Imburu formation of the upper Jurassic mainly consisted of retrogradational sequence with stable mudstone deposition on the top. On the plane, the sedimentary sequence was delta plain-delta front-semi deep water-deep water, with the delta distributing widely. The Papuan fold belt was mainly in the delta front, and the front-end sandbodies were transformed into finger- or point-like ones by the tidal action. (3) The source rocks from the Jurassic Magobu and Koi Iange prodeltas were relatively good, while the winnowed and strongly transformed mouth bars in the delta front had the best physical properties to be the optimal zones for reservoir, and the thrust traps in this belt can be potential exploration targets.