Petroleum geological dynamics of Lower Paleozoic in the Ordos Basin, northwest China

Taking the hydrocarbon source rocks of Ordovician, Lower Paleozoic in the O rdos Basin as the main research object, the characteristics of petroleum ge ological dynamics about geohistory, geothermal history, hydrocarbon generat ion history and hydrocarbon expulsion history were studied by using the met hods of basin numerical modeling dynamically and pool-forming dynamics, it is shown that the Ordovician strata had entirely undergone five stages of i nitial deposition, uplift and erosion, rapid subsidence, alternating uplift and subsidence, and differential uplift and erosion; that under the backgr ound of lower heat flow on the whole, the paleoheat flow of Ordovician stra ta in the basin could be divided into two large stages of relatively high h eat flow values period before Cretaceous deposition and relatively low ones after it; that the thermal evolution of organic matters in the hydrocarbon source rocks of Ordovician had entered into high mature-postmature stage o n the whole and the intensity of gas generated was greater than that of oil generated, the hydrocarbon being mainly natural gas; and that the curves o f the intensity of oil and gas expulsion at each time unit showed the featu re of multi-peak-type, the accumulative intensity of gas expulsion was grea ter than that of oil expulsion. Thus natural gas exploration potential is g ood.