Analysis of Reservoir Characteristics and the Same Main Controlling Factors in Gulong Area of Songliao Basin

Abstract

Due to a breakthrough in the exploration on shale oil in Qingshankou group, the oil layer series in Gulong sag, one of the most significant depressions in Songliao Basin, are once more implemented to be extended in vertical dimension. Its oil-bearing layers in majority are included in sandstone formations such as Heidimiao, Saertu and Putaohua, and shale oil layer in Qingshankou. This paper systematically draws a conclusion on reservoir characteristics of each layer. Under a further study by comparisons, discrepancies have been found out between newly oil layers and the previous ones, achieving a new perception of previous layers, and sequentially providing some basis for new theories visually through a three-dimensional reveal. With a substantial number of data of different layers being applied in the test, a detailed research has been put into practice on mineral constituents, physical characteristics and pore structures, which indicates the mineral constituents of sandstone layers, in formations of Heidimiao, Saertu, and Putaohua, consist mostly of arkose, in the meantime, the reservoir space is formed out of primary intergranular pores in majority and dissolution pores take the second place. Its porosity and permeability tend to descend with the increase in depth, therefore, Heidimiao, which is buried the shallowest, appears to be superior to those formations underneath it in physical properties, of which the permeability changes prominently. However, the shale reservoirs are other than conventional reservoirs, out of which the mineral constituents are mostly clay, intergranular pores, intercrystalline pores and shale bedding fractures can be seen develop and the porosities are inferior to that of sandstones but with a high areal permeability. Overall speaking, the main identical controlling factors that affect the reservoir properties lie in 4 aspects which are environment of sedimentation, grain size, burial depth and diagenetic evolution.

Y. Zhang (1986)–Petroleum engineer, Major: Comprehensive Research of Petroleum Geology