Characteristics Of Igneous Reservoirs And Distribution Prediction Of Oil And Gas In Mesozoic,Huanghua Depression

Focused on the characteristics of igneous reservoirs in Mesozoic Huanghua Depression,comprehensively used the core observations,casting thin sections,X-ray diffraction,scanning electron microscope,conventional pore infiltration data and other analytical test data,and combined with the data of oil and gas migration and accumulation in the basin and the present research achievement,this paper studies characteristics of igneous reservoirs and controlling factors of development in Mesozoic Huanghua Depression in depth.On this basis,the favorable areas of oil and gas exploration are predicted.Studies have shown that the types of igneous rocks in this area are various.The main igneous rocks are volcanic lavas,followed by pyroclastic rocks and pyroclastic sedimentary rocks as well.According to the volcanic mode of action and the characteristics of volcanic products,the facies of igneous rocks are divided into four types: the overflow facies,the explosive facies,the volcanic channel facies and the volcanic sedimentary facies.Studies have shown that the Mesozoic igneous rocks are mainly distributed in the central and southern areas of Huanghua depression,while they are scattered in the northern area.The pore types of igneous rocks in research area are mainly two categories: primary porosity and secondary porosity.The primary pores mainly include primary stomata,residual stomata,intergranular pore and condensation shrinkage joint,the secondary pores mainly include dissolved pores or holes,dissolved fractures and structural fractures and so on,the pore structure is greatly influenced by lithologic facies.The dominant lithology of igneous reservoirs in this area is andesite,and the dominant facies is the overflow facies.The study found that the combination types of reservoir space are mainly divided into four categories: macroscopic poretype,micro-hole micro-seam,isolated pore and crack.The reservoir space in this area is dominated by medium-low porosity and low permeability reservoirs,and the differences in different buried hills are obviously.The development of reservoirs is mainly affected by the factors such as lithology and lithofacies,weathering-leaching,alteration,volcanic eruption cycles,teatonic movement and diagenesis.Lithology and lithofacies are the basis of reservoir development,dissolution and alteration are the decisive factors of reservoir development,weathering-leaching,tectonic action,volcanic eruption cycles and diagenesis are important controlling factors of reservoir development.The oil and gas in the Mesozoic igneous reservoirs in research area are mainly from the Paleogene Shahejie Formation and the Upper Paleozoic source rocks.Hydrocarbon accumulation has two phases of filling and late shaping.Fracture is a favorable oil source supply channel.Generally,the fault is mainly guided by close distance.The oil and gas is mainly concentrated in the high point of the structure or distributed near the fault zone.Based on the distribution of proven igneous reservoirs and combined with hydrocarbon migration simulation,the comprehensive analysis suggests that the medium-acid igneous rocks in Kongxi area,the neutral igneous rocks in Kongdong area and the meso-basic igneous rocks in Qikou area are the favorable exploration area for igneous reservoirs in Mesozoic Huanghua Depression.