鄂尔多斯盆地北缘勘探思路转变与天然气领域重大突破

Transformation of exploration ideas and major breakthrough in natural gas discovery in the northern margin of the Ordos Basin

鄂尔多斯盆地北缘构造转换带发现的东胜气田为近中期中国天然气重要的增储上产阵地之一。"十三五"以来,通过持续深化鄂尔多斯盆地构造、沉积演化特征研究,明确其对烃源岩、储层、输导条件的控制作用,加强盆地区域构造及成藏要素差异配置分析,实现了认识创新和勘探思路转变,明确不同区带差异富集规律,有效指导了盆地北缘致密砂岩气藏勘探突破。研究认为,鄂尔多斯盆地北缘有效烃源岩、储层及侧向输导通道的差异匹配是天然气差异富集的主控因素;处于杭锦旗区块中部的独贵加汗区带继承性古隆起斜坡区下石盒子组具有"源储有效配置、上倾尖灭封堵"的有利天然气富集条件,多期断裂活动为多层气藏形成提供了有效输导通道;独贵加汗区带是勘探开发一体化评价及新层系勘探突破的首选区带。近期该区带提交探明储量超千亿立方米,有效推动开发建产,提升了盆缘天然气资源价值,拓展了勘探领域。

The Dongsheng gas field, discovered in the tectonic transform zone in the northern margin of the Ordos Basin, is one of the important gas reserves and production increase bases in China in the near and medium term. Since the "13 th Five Year Plan" period, the structural and sedimentary evolution characteristics of the Ordos Basin have been continuously deepened, and their control on source rock, reservoir and transport conditions has been defined. The analyses on regional structures and differential configuration of hydrocarbon accumulation factors in the basin have been emphasized, so as to realize the innovation of understandings and the transformation of exploration ideas. The differential enrichment laws of different plays are determined, which effectively supports the exploration breakthrough of tight sandstone in the northern margin of the basin. The study shows that the differential configuration of effective source rocks, reservoirs and lateral transport channels is the main controlling factor of differential gas enrichment in the northern margin of the Ordos Basin. There is a successive developed paleo-uplift slope zone in the Duguijiahan play in the central Hangjinqi area, where the Lower Shihezi Formation has favorable gas accumulation conditions of "effective configuration of source rocks and reservoirs, and sealing by up-dip pinch out". The multi-stage fault activities provided effective transport channels for the formation of multi-layer gas reservoirs. The Duguijiahan play is the first choice for integrated evaluation of petroleum exploration and development, and exploration breakthrough in new strata. Recently, more than 100 billion cubic meters of proven gas reserves are submitted in this area, which effectively promotes the development and productivity construction, improves the value of natural gas resources in the margin area of the basin, and expands the exploration field.