鄂尔多斯盆地西南部致密砂岩气成藏主控因素

Key Controlling-factors of Tight Sandstone Gas Accumulation in the Southwestern Ordos Basin

鄂尔多斯盆地西南部上古生界砂岩储层整体较为致密,已获得工业气流,成为鄂尔多斯盆地致密砂岩气储量接替区。为了明确该盆地西南部致密砂岩天然气成藏的主控因素及规律,运用气源条件、源储空间配置和储层质量等单因素叠合分析方法进行综合研究。研究表明:盆地西南部上古生界气源强度满足形成致密砂岩气藏的成藏下限要求,与烃源岩空间配套的致密砂体宏观上控制气藏的位置和规模,致密砂岩内石英含量及其孔喉连通程度微观上控制致密砂岩气藏的富集程度,而气源条件、源储配置和储层质量三元补偿的最佳配置区为天然气的高产区。研究结果为盆地西南部致密砂岩气藏的勘探开发提供了科学依据。

Industrial gas production has been gained in the Upper Paleozoic relatively tight sandstone reservoir in the southwestern Ordos Basin,which has been considered as a tight sandstone gas replacing area in Ordos Basin. In order to determine the key controlling- factors and regulation of tight sandstone gas accumulation in the southwestern basin,multi-factor integration analysis is used perform comprehensive study by using gas source properties,special source-reservoir combinations and reservoir properties. Research shows that the Upper Paleozoic gas source intensity reaches the lower limit of tight sandstone gas accumulation in the southwestern basin. The gas reservoir position and scale are controlled by the tight sandbodies matching with source-rocks at macro level. The enrichment degree of tight sandstone gas reservoir is controlled by the quartz content and pore-throat connectivity at micro level. High gas production will be gained in the area with favorable combination of gas-source properties,source-reservoir combination and reservoir properties. This research could provide a scientific reference for the exploration and development of tight sandstone gas reservoirs in the southwestern basin.