Petroleum Accumulation System And Resources Assessment, A Case Study Of Ordovician In Tazhong Area, Tarim Basin

Accumulation regulations and resource assessment of marine carbonate in superimposed basins have been a focus for a long time, also be a bottleneck for exploration improvement of Tazhong District. Not only do those theories concerning the process of hydrocarbon generation, migration, trap and accumulation help researchers get more correct analysis of accumulation regulations and resource assessment than ever in Tazhong district, but also they should be verified and play a key role for exploration in marine carbonate in China superimposed basin .As to the hydrocarbon distribution regulation in superimposed basin, we guided by the petroleum accumulation system theory, analyze the petroleum geologic elements'combination following source-location configuration, investigate the pools distribution and main controlling factors through typical pools anatomy, simulate the hydrocarbon formation and evolvement process using forward-inverse modeling. Here some conclusions are made and verified by those methods. There exist three tectonic events for making in-place accumulations corresponding to three stages of hydrocarbon expulsion and accumulation cycles demonstrated by kinds of simulations: Late Caledonian-Early Hercynian stage, Late Hercyin hydrocarbon accumulation, loss and paleo-reservior modification stage, Yanshan-Himalaya stage. The latter stages attributed more to accumulation. The petroleum system anatomy concludes the primary factors controlling the accumulation regulations respectively. Source rock and structural configuration affect the accumulation location, faults are the main pathways of hydrocarbon migration, and seal preserve hydrocarbon effectively.This thesis also discusses and develops the existing and latest resource assessment methods applied to varieties of hydrocarbon accumulation units of marine carbonate. For genetic methods, hybrid approaches were combined to simulate the hydrocarbon migration and accumulation based on the sophisticated geologic model, which is effective to determine migration and accumulation parameter of marine carbonate rocks. For those statistical methods, taken General Pareto Method as example, q0(minimize reservoir size), qmax(maximized reservoir size ) , r(median reservoir size ) ,λ(distribution Feature Parameter) are suggested to be key parameters. Especially, equations for obtaining general Pareto key parameters for middle-lower exploration degree basin are highlight.Above two kinds of assessment methods are applied to assess the Tazhong Ordovician resource respectively. With application of those genetic methods, Tazhong Ordovician oil resource in-place 1.34 billion ton, gas in-place 0.53 billion ton equivalents,1.88 billion ton total. With application of those statistic methods for oil reservoirs, reservoir total number estimated is 147, resource in place is 0.782 billion ton. With application of those statistic methods for gas reservoir, gas reservoir total number estimated is 76, gas resource in place is 512. 58 billion cubic meter.Considering the assessment results of hydrocarbon accumulation regulations and resource potential and the analysis involving the source rock condition, traps determination degree, reservoir and seal conditions, migration and favorable hydrocarbon conditions, reservoir existed and oil shows, this thesis proposes that the Ordovician carbonate favorable areas for Sinopec in three orders: the first ones should be Shunxi district in northwest, ka 4 district in the east of the Tazhong I slope primary; ka 1 district along TazhongⅡback thrust belt should be secondary, and ka 2,3 district, southern slope of Tazhong are third ones as risk exploration area.