中国陆相湖盆致密油成藏主控因素综述

Main controlling factors for tight oil accumulation in continental lacustrine basins in China

马洪 李建忠 杨涛 闫伟鹏 唐惠 郭彬程 黄福喜 吕维宁

Ma Hong Li Jianzhong Yang Tao Yan Weipeng Tang Hui Guo Bincheng Huang Fuxi Lü Weining

中国石油勘探开发研究院, 北京 100083

Research Institute of Petroleum Exploration and Development, PetroChina, Beijing 100083, China

致密油是指致密储层中的石油聚集,储层主要为致密砂岩和碳酸盐岩2大类,覆压渗透率多小于0.1×10-3 μm2,一般无自然产能,需经技术改造方能获工业油流。我国主要发育陆相湖盆致密油藏,通过对比研究分析发现,发育优质烃源岩、存在"甜点区"、具备成藏原动力、近源聚集是我国陆相致密油成藏的主要条件。我国陆相致密油主要发育2类优质烃源岩:Ⅰ类烃源岩有机质类型好、丰度高,有机质成熟度高,生烃潜力大;Ⅱ类烃源岩生烃转化率较高。发育致密砂岩和碳酸盐岩2类储层,储层具有较强的非均质性,横向不连续,垂向叠置分布。生烃增压是我国陆相致密油成藏的主要原动力,强大的源储压差驱替生成的石油向紧邻优质烃源岩的致密储层中持续充注;其中,微裂缝沟通、微—纳米孔发育是致密油运移聚集的关键。微—纳米孔发育增大了致密储层的有效储集空间,微裂缝沟通为致密油的运移聚集提供了有效通道。我国陆相致密油资源丰富,初步预测其有利勘探面积约16×104 km2,地质资源量约(160~200)×108 t,有利勘探领域主要分布在鄂尔多斯、准噶尔、松辽、渤海湾、柴达木、四川等盆地。

Tight oils refer to the oils accumulated in tight reservoirs. The tight reservoirs mainly include tight sandstones and carbonate rocks, with in-situ permeability less than 0.1×10-3 μm2. There is no natural production normally, and commercial oil flows can be obtained through technical reconstructions. In China, the tight oil reservoirs in continental lacustrine basins are developed, and four controlling factors for tight oil accumulation have been concluded as followed: developing superior hydrocarbon source rocks, being preferable reservoirs, possessing original driving forces and accumulating near to source rocks. Two types of high-quality hydrocarbon source rocks developed in the continental lacustrine basins in China. The source rocks of type Ⅰ have superior organic type, high organic content, high maturity, and big hydrocarbon generation potential. The source rocks of type Ⅱ are outstanding in hydrocarbon transformation ratio. Tight sandstones and carbonate rocks work as the main reservoirs for tight oils, and are featured by strong heterogeneity (discontinuous in transverse and superimposed in vertical). Generated hydrocarbon pressurization is the main driving force for tight oils in China. Powerful pressure differential between source rocks and reservoirs displaced the generated oils to fill the tight reservoirs continuously which were close to high-quality hydrocarbons. Micro-crack in communication and micro-nanometer pore development were the key conditions for tight oil gathering. Micro-nanometer pore development increased the effective reservoir space and micro-crack in communication provided the effective channel for tight oil gathering. The tight oil resources are rich in China. The favorable exploration area is about 16×104 km2, and the geological resources are about (160-200)×108 t. The favorable exploration areas mainly distribute in the Ordos, Junggar, Songliao, Bohai Bay, Qaidam and Sichuan basins, and so on.

国家科技部重大专项"大型油气田及煤层气开发"(2011ZX05043)资助。

https://doi.org/10.11781/sysydz201406668