西西伯利亚盆地侏罗系致密油发育特征与资源潜力

Characteristics and resource potential of Jurassic tight shale oil reservoirs in West Siberian Basin

西西伯利亚盆地是全球几大富油气盆地之一,随着常规油田的不断开发,产量持续下降,迫切需要找到新的产能增长点。通过对该盆地主力烃源岩巴热诺夫组的地球化学、储层物性等多方面分析,探索其致密油发育特征,并利用图形体积法对其致密油技术可采资源量进行评价,结合巴肯组、鹰滩组、延长组等典型致密油产区进行对比,综合分析其致密油可采性。结果表明:巴热诺夫组是一套极好的烃源岩,具有高有机质丰度、中等成熟度,厚度大。储层岩性以灰质硅质岩、泥质硅质岩为主,夹薄层碳酸盐岩和粉砂岩,泥质含量低,富含石英等脆性矿物,部分地区天然裂缝非常发育。储层以Ⅰ类和Ⅱ类致密油储层为主,测井显示含油饱和度高。巴热诺夫致密油技术可采资源量达76×108t,Ⅰ类致密油储层技术可采资源为9.2×108t,盆地中西部资源丰度较高。综合考虑配套工业设施等可采条件,目前中鄂毕地区是最为有利的致密油开采区,其关键地质条件也均已达到世界级致密油产区的标准。

The West Siberian Basin is one of the richest world-class petroliferous basins. With continuous development of the conventional oil, the oil production is declining continuously, so it is an urgent need to find new growth points of the oil production. The characteristics of its shale oil reservoirs are studied through analyses of the geochemical characteristics and reservoir physical properties of the main source rocks of the Bazhenov Formation in the basin, and the technical recoverable tight oil resources are estimated by using the graphics-volume method. Also the recoverability of the Bazhenov tight oil is evaluated comprehensively through comparison with some famous tight oil plays, such as Bakken, Eagle Ford and Yanchang tight oil plays. The result shows that the Bazhenov Formation is an excellent source rock featuring in high organic matter abundance, moderate maturity,large thickness of 20 -50 meters. The lithologies are dominated by carbonate silicates and shaly silicates with interbeds of carbonates and siltstone. The quartz content is high, the clay content is low, and natural fractures are highly developed in local areas. The reservoir belongs to type I and type Ⅱ tight reservoir with high oil saturation. The technical recoverable resource of the Bazhenov tight oil is 7.6 billion tons, and class I resource of tight oil is 0.92 billion tons, which are mainly distributed in the central and west region of the basin. Taking the available facilities into consideration, the Central Ob ,with all the key geological conditions at the standards of world-class tight oil plays, is the most favorable area for future development.