Shale Oil And Gas Accumulation Conditions And Distribution In Liaohe Depression

Liaohe Depression is a typical Cenozoic continental rifted basin, with rich oil and gas resources and superior Petroleum Geology conditions. In this paper, a great quantity of experimental data collected from various tests has been analyzed, such as chemical tests data, isothermal adsorption results, field desorption results, high pressure simulation experiment data and so on. Based on these data, this paper comprehensively discussed generation condition, enrichment mechanism and controlling factors of shale oil and gas of Paleogene in Liaohe Depression. By using physical simulation combining with geological analysis, developmental characteristics and generation mechanism of continental shale oil and gas in fault basin have been built, the favorable areas in Liaohe Depression has been selected and resource quantity has been evaluated. Results show as follows:(1) Continental shale has several characteristics, such as small thickness of single-layer, large thickness of total layers, rapid facies change, development of sand interlayer, various organic matter types, limit thermal maturity and high content of clay minerals. Organic matter types of continental shale in Liaohe Depression vary from Ⅰ to Ⅲ. The average TOC is 2.67%. Ro ranges from 0.4% to 1.5%. Content of clay mineral is of an average of 46.2%. And there are plenty of various types of pores and cracks in the shale, providing accumulation conditions of shale oil and gas. The most significant controlling factor of shale oil and gas generation and accumulation is the match of the specific organic matter type with thermal evolution degree.(2) From the bottom layers to the top, the subsidence and deposition centers to the edge, the type of organic matter changes regularly from type I to type III. The thermal maturity degree gradually increased with the increase of burial depth. These patterns, adding to differences of hydrocarbon generation models and their productions of diverse organic matter types, lead to a distribution of shale oil and gas regularly on both vertical and lateral direction in fault lake depression. Vertically, from the bottom of the depression to the upper, shale oil and gas, shale oil, shale gas developed sequentially. Meanwhile, in lateral direction, from depocenter center to the edge of the depression, the dominant shale oil area gradually transit into shale gas favorable area. The slope area is usually characterized by shale oil frequent interbedded with gas. Therefore, the favorable areas represent as a circle from the plane view:in the middle of the depression is distributed with shale oil, while on the edge is gas. Between them is the transition zone developed both oil and gas.(3)The favorable areas of shale oil and gas distribute around the depocenters of three subsidiary sags. The most favorable areas for shale oil is Qingshui subsag and Panshan-Chenjia subsag in West Sag, as well as Rongshengbao Subsag and Anfutun Subsag in Damintun Sag. Erjiegou-Jiazhangsi Subsag and Niuju-Changtan Subsag in East Sag are considered as most valuable for shale gas. The geological resources of shale gas is 12231.01×108m3 and the recoverable resources is 2690.82×108m3; while for shale oil, the geological and recoverable resources are 78640.67 X 104t and 7864.07 X 104t.This paper not only plays an assistant role on development of shale oil and gas in continental fault depression of China, but also has a certain guidance on exploration and development of shale oil and gas in Liaohe Depression.