Porosity Evolution of the Upper Paleozoic Reservoir in Eastern Ordos Basin

TIAN Xia-he;QU Hong-jun;WEI Xin-shan;LIU Xin-she;YANG Huan;CHEN Ya-hui;DONG Wen-wu;Northwest University;Research Institute of Exploration and Development,Changqing Oilfield Company,PetroChina;

the eastern Ordos Basin;;porosity evolution;;diagenesis;;Upper Paleozoic

The Upper Paleozoic reservoir in the eastern Ordos Basin is a typical ultra-low porosity and ultra-low permeability reservoir,by studying the diagenetic evolution and porosity evolution history of the area,it is of great importance for understanding the compact process of the Upper Paleozoic reservoirs in the eastern Ordos Basin.On the basis of analyses of cast thin sections,scanning electron microscopy,cathode luminescence,X-ray diffraction analysis of clay minerals,porosity evolution of the eastern Upper Paleozoic reservoir in Ordos Basin is simulated and analyzed.The results show that the main diagenesis,compaction and cementation in the study area are the main factors inducing the loss of porosity,the dissolution of reservoir play a constructive role in the porosity evolution,Through the process of recovery porosity evolution,the original porosity of the study area is about37%,with long-term compaction,more than half of the porosity is lost,after a multi-stage cementation,the reservoir becomes dense with few pores,but at the same time the porosity experiences the two phase dissolutions.