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    南海北部潮汕坳陷侏罗系古地貌特征及沉积相模式

    Paleogeomorphic features and sedimentary facies model of Jurassic strata in Chaoshan sub-basin, northern South China Sea

    • 摘要: 南海北部潮汕坳陷中生界极具油气勘探潜力;综合运用最新采集的地震资料结合测井数据,在侏罗纪地层精细划分的基础上,通过对目的层剥蚀量计算,对侏罗系古地貌进行了恢复;利用残留地层的沉积相标志分析结果,建立了潮汕坳陷侏罗系沉积模式。结果表明,在早侏罗世末期和中侏罗世末期,地层遭受剥蚀改造;古地貌各要素对沉积体系发育的影响,古隆起(凸起)指明了沉积物的来源和方向;古海底峡谷是沉积物从物源区搬运到沉积区的重要运移通道;斜坡带为重要的沉积场所,并对储层的品质和规模有巨大影响,制约着盆地可容纳空间的大小;盆底的地貌形态控制着沉积体形态和产状。研究结果表明,古地貌恢复后的各要素在时空上的有效配置关系是准确把握沉积体系展布特征及范围的关键因素,对沉积储层及烃源岩的控制作用非常明显。该结论对侏罗系下一步勘探及有利储层预测有积极意义。

       

      Abstract: The Mesozoic strata in the Chaoshan sub-basin of northern South China Sea have rich oil and gas resources. Seismic data and well logging data were used in combination with fine stratigraphic division and denudation calculation to restore paleogeomorphology of the Jurassic sedimentary strata.On the basis of sedimentary facies marker analysis of residual strata, a Jurassic sedimentary model was established. The Jurassic strata suffered denudation alterations at the end of Early Jurassic and Middle Jurassic. Various elements of paleogeomorphology influenced sedimentary system development. Ancient uplift (bulge) indicated the source and direction of sediments. The ancient sea bottom canyon was an important transport passage between source and sedimentation. The slope zone was an important deposition site and had great influence on the quality and size of reservoirs, thus restricting the accommodation space of the basin. The basin bottom (depression) topography controlled the morphology and occurrence of sediments and influenced the quality and size of source rocks. Effective combination of all the elements of paleogeomorphology in time and space seems to be the key to accurate determination of the distribution and range of a sedimentary system, and its control of sedimentary reservoirs and source rocks is very obvious. The conclusion has positive significance for the next exploration and favorable reservoir prediction of the Jurassic strata.

       

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