Reservoir Characteristic Comparison and Difference Analysis of Volcanic Reservoirs in the Paleo-Asian Domain's Basin,China

According to analysis of the ages and lithology of parent rocks in volcanic reservoirs,the types of reservoir space and lithofacies of volcanic rocks,which distribute in the basins all around the paleo-Asian tectonic domain of China,the article discusses the reservoir characteristics and difference of volcanic oil and gas pool.In the paleo-Asian tectonic domain of China,the research indicates that the parent rocks in volcanic reservoir develop in a regular pattern:western parent rocks age is older than eastern.The Junggar basin,Santanghu basin and Tuha basin which located in the west develop marine and marine-terrigenous medium-basic andesite,basalt and pyroclastic rocks of the late Palaeozoic;and the Songliao basin,Erlian basin and Hailaer basin located in the east develop continental intermediate-acid rhyolite and andesite of the Mesozoic.The primary reservoir space of volcanic rock includes pores,cavity and solidification contraction fractures;the secondary reservoir space includes various of dissolved pores,structural fractures and weathered fractures.The volcanic lithofacies can be divided into extrusive facies,conduit facies,subvolcanic facies and volcanic sedimentary facies.Most of intermediate-basic rocks begin with effusive facies,and the type of phase sequence is effusive facies,explosive facies/volcanic sedimentary facies;Most of the intermediate-acid rocks begin with explosive facies or conduit facies,the main phase sequence is explosive facies,effusive facies/extrusive facies.The effusive facies develop primary pores and structural fracture;Explosive facies develop intergranular pore;Inter-breccia pore and primary fracture are dominant in the extrusive facies.Several factors affect the difference of volcanic reservoir,such as lithology and lithofacies,eruption environment,late reformation and diagenesis.The first two factors control the formation and distribution of volcanic reservoir and development of reservoir space;the rest reform storage property and permeability of the reservoir.