The Study On Rock Types And Distribution Of Buried Hill In Hailar-Tamtsag Basin

The Hailar-Tamtsag Basin is one of most important basins which bearing oil and gas in the Mongolia-DaHinggan folded belts basin group, and now it has become highlight exploration and development area in periphery basins of the Daqing oil Field. The buried hill reservoir exploration has been dived on prologue and become the aim to increasing petroleum reserves, since the discovery of Sudeerte buried hill reservoir in 2001. As well as we know, reservoir is one of the key factors of buried hill hydrocarbon accumulation, and it is also the foundation of reservoir research to deal with rock-types, lithofacies, reservoir spaces type and its formation mechanism. At present, because the origin of buried hill is most complicate and the study on the rock-types and distribution in the Hailar-Tamtsag basin is also blank, that have seriously affected the process of oil or gas exploration and development. In this paper,the rock-types and distribution,"lithology-electric property"relationship, reservoir space type, characteristic and forming mechanism of buried hill reservoirs in Wuerxun, Beier, south Beier and Tamtsag South Sag depression have been researched, on the basis of the observation of drilling cores and the identification of a large number of thin slices, combining with such data as well logging, seismics and non-seismic attributes. In this paper, some important results have been obtained: (1) Impacted on the frequent volcanism in the Late Jurassic-Early Cretaceous of Mongolia-DaHinggan folded belts basin group, there are detrital material and pyroclastics simultaneously in this basin. The pyroclastic rock and clastic rock are the major type of rock, and there also exist slag and ganite. Especially, it is the first time that pearl spar was found in this area. (2) Through the analysis of the rock distribution in vertical, flat and profile, it is found that the base of Hailar-Tamuchage and buried hill types are closely related to the hypsography and volcanism. (3) It is investigated that the rock distribution is controlled by the eruption of central type in Beier sag, and the igneous-related lithofacies and distribution mode of Budate group are established. (4) The main reservoir space is a complicated reservoir and the permeation system is made up from fracture and pore, fracture is major and pore is minor which is also controlled by fracture. Tectonic and faulting, lithofacies, weather-worn and fluid is the chief four factors that affected formation of reservoir. Original accumulation types are mainly controlled by lithology and lithofacies, and secondary cavern and fracture is affected by the other three factors.(5)After the factors which affect reservoir development are analyzed comprehensively, reservoir formation condition is analyzed and favorable reservoir area in this four depressions is also predicted, that lay a foundation for reservoir play research and oil or gas exploration.