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    济阳坳陷车15井区浊积扇沉积及油气勘探意义

    Turbidity fans and hydrocarbon prospecting of lower 3rd Member of Shahejie Formation from well Che15, Jiyang depression

    • 摘要: 提要:根据岩心、地震、测录井资料,在济阳坳陷车镇凹陷车15井区的沙三下砂砾体中识别出滑塌浊积扇和深水浊积扇。其中,车古25井以具水道补给的(有根的)滑塌浊积扇为特色;内扇及水道最发育,为碎屑流夹浊流的巨砾岩、中细砾岩(厚10~20 m)与砾质砂岩夹薄层深灰、灰色泥岩;崩塌成因的巨砾(大小1.06 m)反映了陡的斜坡;地震上呈楔状外形,内扇为弱反射,中扇与外扇为发散、亚平行的连续反射。车57井以粒度偏细且有根的深水浊积扇与深湖相互层为特色;中扇发育,为厚(5~11 m) 的水道碎屑流细砾岩与砾质砂岩,夹深灰色泥岩;水道沉积表现为钟型测井曲线。顺水道方向滑塌浊积扇由北而南产生进积,向盆出现深水浊积扇;2类扇体沿主构造线串珠状排列,包裹于大片的深湖相中,呈现“深湖包扇”的沉积格局。不同类型浊积扇的识别及其边界的确定,对于该区隐蔽圈闭勘探具有重要意义。

       

      Abstract: Abstract:Based on seismic, well-logging and core data, the authors recognized the deep-water turbidity fans and slide turbidity fans developed in the lower 3rd Member of Shahejie Formation from the well block Che 15 in Chezhen sag, Jiyang depression. Well Chegu 25 is characterized by the slide turbidity fans with supplied or rooted channels, where the inner fan and its channels are especially developed, and are composed of debris-flow and a few turbidity-flow boulder-, cobble- and pebble-conglomerates with thickness of 10 to 20 m and gravel sandstones bedded with thin-layer dark grey or grey mudstones; the conglomerates of falling-boulder 1.06m in size reflect steep slope topography. On the seismic profiles, the fans assume wedge form, where the inner-fan is weakly reflected, and the middle- and outer-fans are of divergently and subparallelly continuous seismic reflection configuration. Well Che 57 of fine-grained sediments is characterized by the deep-water turbidity fans with rooted channels and deep lacustrine facies, where the middle-fans are especially developed, and are composed of debris-flow pebbly-conglomerates with thickness of 5 to 11m and gravel sandstones interlayered with dark grey mudstones; the well-logging curve pattern of channel sediments is bell-shaped. it is concluded that the slide turbidity fans experienced progradation along the channels from north to south, and the deep-water turbidity fans occurred in the central lake; two types of fans were disposed in the pinch-and-swell form along the main tectonic orientation, and were wrapped in extensively-distributed deep lake facies, assuming the sedimentary framework of “fans packaged in deep-lake”. The recognition and confirmation of boundaries of the turbidity fans is of great significance for hydrocarbon prospecting of the subtle traps.

       

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