Study Of Tectonic Evolution And Oil And Gas Reservoir Forming Conditions Of Chuxiong Basin

This paper is to research on the structure and tectonic evolution characteristics of Chuxiong basin,clear the fault of basin and its space distribution characteristics,ensure the effect of basin tectonic evolution and fault activity on oil and gas accumulation and choose oil and gas resource perspective area of Chuxiong basin by the comprehensive explanation and study of surface geology, drilling and seismic data, combined with the research results of previous studies on the structure,tectonic evolution,source reservoir cap, insurance and other basic petroleum geological conditions of Chuxiong basin,. contact with the structural pattern of the basin and evolution characteristics of Chuxiong basin. We hold of the key problems as matching relation between the trap formation period and the main stages of hydrocarbon generation and expulsion and the transformation of different tectonic movements on the oil and gas reservoir damage properties,and analysis the petroleum geological conditions of tectonic evolution and hydrocarbon occurrence. In the process of completing the paper, the author consults 128 research papers about construction of Chuxiong Basin,sedimentary strata,reservoir evolution and study of source rock;collect the data of regional geology, resources evaluation,restoration and evaluation of prototype basin,study of preservation condition and associated seismic profiles and drilling data of 3 wells;carry on 820 profile kilometers of geological interpretation of seismic profile; investigate 75 profile kilometers of field geologic.We accept congnization of the exploration prospect of Chuxiong basin through the work above.(1) In early Late Triassic the Chuxiong basin(Yunnanyi Group and Luojiadashan group) belongs to the foreland basin. Ailao Mountain is the orogenic belt associated with it.Its leading edge locates in the western part of nappe zone(Yunnanyi group and the deposition of Luojiadashan group were more than 1000m thickness).In Late Triassic to Cretaceous Chuxiong basin is a fault depression basin.But but in the Himalayan it had been changed strongly.Due to only a small amount of Paleogene develop near Yuanmou Hump,on the whole this basin is a Mesozoic remnant cratonic downwarped basin.(2) The main hydrocarbon source rocks in the basin (upper Triassic) are distributed in West and they have good hydrocarbon source condition.and the hydrocarbon source rocks of eastern basin Yunlong and Dongshan are Lower Cambrian and Devonian source rock.But its scale is limited,and there are a large number of oil seepage, gas seepages and asphalt in the western part of the basin.So the western basin has better reservoir forming conditions.(3) Basin in the western thrust nappe belt deposits thick Yunnanyi group and Luojiadashan Group.hydrocarbon source condition is good and the multi period tectonic movement forms numerous traps and size. Surface has much asphalt and oil seepage.There should be secondary reservoir structure after reform.(4) The structures of the depression in the central basin are influenced by the late Himalayan movement transformation strongly.But then the source rock of upper Permian came into peak stage of gas formation and it has conditions to form gas reservoir structure.It can also transform the structure of late accumulation in early Yanshan and forms secondary hydrocarbon reservoir.(5) Western overthrust fault zone is footwall structure,with near oil source, weak tectonic effects suffered, preservation condition is relatively good.It should be the next exploration target in western Nappe belt,which may also be one of the oil and gas exploration breakthrough objectives in Chuxiong basin.