川西南部地区上三叠统构造及断裂特征
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摘要
川西南部地区须家河组是四川盆地重要的天然气产层,数十年来在该区进行了近万平方公里的数字地震勘探,发现和查明构造圈闭数十个,钻井百余口,在平落坝、邛西等地须家河组中发现了储量极为丰富的天然气田。2003年根据这些地震及钻探资料,对该区上三叠统构造进行连片解释,总结了该层系的断裂和褶皱特征,初步在川西南部地区上三叠统构造中划分出3个具有不同断褶特点的次级构造区带——西界山前断褶区、中部滑脱构造区、南部断隆构造区。西界山前断褶区的断褶强度大,构造相对破碎;中部滑脱构造区以中等强度的褶皱背斜发育为特征;南部断隆构造区更多地受到盆地南边峨眉山、凉山断块的影响,表现出浅中深层构造同时断褶的特点,与前述两区的断褶特点明显不同。连片地震勘探成果为更深入研究该地区油气成藏机制奠定了良好基础。
The Xujiahe Fm in Southwest Sichuan is the major gas reservoir in Sichuan basin. Over the past several decades, digital seismic data of near ten thousand square kilometers have been acquired in this area, tens of structural traps have been discovered and proven, over one hundred wells have been drilled, and gas fields with abundant reserves have been found in the Xujiahe Fm in Pingluoba and Qiongxi. In 2003, based on these seismic data and drilling data, multi-survey seismic interpretation was performed on the Upper Triassic structures in this area and the characteristics of the faults and folds were summarized. The Upper Triassic structures in Southwest Sichuan are preliminarily divided into 3 secondary structural belts with distinct fault-folding characteristics, including the piedmont fault-fold belt on the western edge, the central decollement belt, and the southern rifted uplift belt. Fault-folding is very intense in the piedmont belt on the western edge, resulting in relatively fractured structures. The central decollement belt is characterized by moderately folded anticlines. The southern rifted uplift belt is characterized by the contemporaneous rifted uplifting of the shallow, middle and deep structures, which is obviously different with the former two secondary structural belts, due to the more intense influences of Emei Mountain and Washan Mountain fault block to the south of the basin. Multi-survey seismic interpretation provides a good basis for further study of the oil and gas reservoiring mechanism in this area.
The Xujiahe Fm in Southwest Sichuan is the major gas reservoir in Sichuan basin. Over the past several decades, digital seismic data of near ten thousand square kilometers have been acquired in this area, tens of structural traps have been discovered and proven, over one hundred wells have been drilled, and gas fields with abundant reserves have been found in the Xujiahe Fm in Pingluoba and Qiongxi. In 2003, based on these seismic data and drilling data, multi-survey seismic interpretation was performed on the Upper Triassic structures in this area and the characteristics of the faults and folds were summarized. The Upper Triassic structures in Southwest Sichuan are preliminarily divided into 3 secondary structural belts with distinct fault-folding characteristics, including the piedmont fault-fold belt on the western edge, the central decollement belt, and the southern rifted uplift belt. Fault-folding is very intense in the piedmont belt on the western edge, resulting in relatively fractured structures. The central decollement belt is characterized by moderately folded anticlines. The southern rifted uplift belt is characterized by the contemporaneous rifted uplifting of the shallow, middle and deep structures, which is obviously different with the former two secondary structural belts, due to the more intense influences of Emei Mountain and Washan Mountain fault block to the south of the basin. Multi-survey seismic interpretation provides a good basis for further study of the oil and gas reservoiring mechanism in this area.
引文
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