基于二维地震的无为盆地构造特征解析与页岩气钻探目标区优选

    Structural characteristic analysis and shale gas drilling target optimization of Wuwei Basin based on 2D seismic data

    • 摘要: 全国页岩气地质资源量评价结果表明下扬子地区无为盆地二叠系具有良好的页岩气资源前景,然而无为盆地当前的勘探程度较低,资料相对匮乏,难以有效地支撑页岩气选区评价和勘探部署。研究依托无为盆地二维地震资料,进行叠前地震处理流程优化和参数优选,开展层位构造解释及时深转换,揭示了盆地的结构、断裂特征和地层发育特征,以及盆地内页岩气主要目标层二叠系的分布、构造、埋深、厚度等地质条件。结果表明: 无为盆地主要发育NE向断裂,其控制着盆地的构造格局,以及盆地内沉积体系的发育与展布,具有纵向分层、横向分带的特点; 纵向上无为盆地以印支面为界,下构造层以逆断层发育为主,上构造层以正断层发育为主; 横向上盆地古生界—中生界“两凹夹一隆”的构造形态呈现出NE走向的条带状展布特征。根据页岩气烃源岩和储层条件,以及构造保存条件等因素,综合研究圈定无为盆地页岩气勘探远景区,并在二维地震测线上优选了3处钻探目标区。研究成果可为在无为盆地内进一步开展页岩气勘探提供物探依据,为下扬子地区油气调查突破提供有效的数据支撑。

       

      Abstract: National shale gas resource assessments indicate that the Permian strata of Wuwei Basin in the Lower Yangtze region has favorable shale gas potential. However, the basin remains underexplored, and the available geological and geophysical data are insufficient to support robust area selection and exploration deployment. Based on the newly acquired 2D seismic data, the study carried out prestack seismic processing, horizon and fault interpretation, and time-depth conversion, and delineated the structural framework, fault characteristics, and stratigraphic distribution of the basin, and the distribution, structural configuration, burial depth, and thickness of the Permian shale gas target interval. The results showed that NE-trending faults controled the basin architecture and the spatial distribution of sedimentary systems, producing a pattern of vertical stratification and lateral zonation. The Indosinian unconformity separates a lower structural unit dominated by reverse faults from an upper structural unit dominated by normal faults. In plan view, the Paleozoic-Mesozoic succession exhibited a NE-trending belt-like configuration of two sags flanking an uplift. By integrating shale gas geological conditions, target-interval thickness, burial depth, and structural preservation conditions, favorable prospect areas were delineated and three preliminary drilling target areas were selected along the 2D seismic profiles. These results could provide geophysical basis for further shale gas exploration in Wuwei Basin and support oil and gas geological survey in the Lower Yangtze region.

       

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