Reservoir Characteristics Of The Triassic Baikouquan Formation In The Mahu Sag, Junggar Basin

Mahu depression Triassic Baikouquan formation development thick sand conglomerate, is a low porosity and low permeability reservoir, with contiguous scale into reservoir, locally high yield, the accumulation characteristics of, is the important exploration areas in Junggar basin scale oil and gas exploration. However, by the control of sedimentary facies and sedimentary model, the complex structure, diversity of structure and physical properties of the gravel group are complex, and the difference of physical property and the lateral variation is fast, so it is important to strengthen the study of reservoir characteristics in this area. The sedimentology, petrology, reservoir geology, storage layer of Geochemistry and geophysics method to use, alignment Junggar basin circum Mahu depression Triassic Baikouquan group sand conglomerate reservoir study and evaluation system, in order to reflect the various genetic types of sand conglomerate depositional environment and depositional model of fan delta sedimentary facies lithologic phase model and the reservoir classification and evaluation scheme, and the Triassic Baikouquan formation reservoir classification and evaluation, made the following understanding.Research on reservoir characteristics show, Triassic Baikouquan formation reservoir formed in the sedimentary environment of fan delta, rock compositional maturity is low, medium maturity, strong reservoir heterogeneity, reservoir conditions for the poor-poor, the pore types are mainly residual intergranular pore and intergranular dissolution pore; excellent reservoirs are mainly developed in the strong hydrodynamic conditions, and better stability of the fan delta front underwater distributary channel microfacies, gray glutenite fan delta front mouth bar and distal bar of gray sandstone, poor reservoir is mainly brown sandstone, fan delta plain braided river fan delta distributary channel main channel gray conglomerate, the fan delta front underwater distributary channel at the end of gray fine sandstone.Triassic Baikouquan formation layer are subjected to the strong influence of rock, sedimentation and diagenesis are on the physical property of reservoir produced great influence, but in contrast into the greater impact on the study area reservoir diagenesis, especially the improvement of dissolution and tectonic effect on reservoir physical property has important significance.Based on the above research, determine the criteria for reservoir classification, the Mahu depression Triassic Baikouquan group reservoirs are classified into three types, which class I and class II reservoirs for high quality and good storage layer, is conducive to the accumulation of oil and gas; class III reservoir relatively dense, is not conducive to the accumulation of oil and gas.