Abstract:Paleoporosity and its evolution of sandstone reservoir is a hard and key task for studying the mechanism of hydrocarbon accumulation. Current methodology has some limitations. It can not take all controlling factors into consideration, the application process is too complicated, the precision of result is low and it can not embody the whole process of porosity evolution. Based on the project which studies on the mechanism of hydrocarbon accumulation within Chang Formation in Zhenjing area of Ordos Basin, a newly methodology to restore the paleoporosiy of sandstone is presented. This methodology is based on diagenetic history of strata and takes constructive and deconstructive diagenesis of porosity into account. With the effect-oriented simulation as the principle, the simulation process is divided into porosity decrease process and increase process. With the geological time as variable and constrained by the current porosity, the model demonstrates dynamic and reliable characteristics. The application of this methodology to Zhejing Area indicates that the evolution of the sandstone porosity is controlled by structure and sedimentary facies, and the distributary channel sandbodies along the up-lip direction of the monocline is the favorable location for the high-quality reservoirs. The process of porosity evolution of sandstone is a key control factor for a high-production hydrocarbon accumulation.