Novel Methods of Identifying Hydrocarbon Bearing Formation with Low Resistivity Contrast from Conventional Logs in Tight Sandstone Reservoirs of North Ordos Basin

Abstract

Abstract It’s difficult in identifying hydrocarbon bearing formation from conventional logs in tight sandstone reservoirs due to the low resistivity contrast caused by the complicated pore structure and high water saturation in north Ordos basin. The experiment of relative permeability illustrates that the water saturation of the target Chang 6 Formation mentioned in this study reach to 58%. To identify hydrocarbon bearing formations from water saturated layers, a method, which is the minimal resistivity method is introduced. To obtain the minimal resistivity of hydrocarbon bearing reservoir, two novel methods, which are formation simulation and rock resistivity experiments, are proposed in this paper. The results shows that the minimal resistivity of hydrocarbon bearing layer in Chang 6 Formation is 40Ω.m. Field examples shows that the proposed methods are effective in obtaining the minimal resistivity and identifying hydrocarbon bearing formations with high water saturation, they can be extended widely in other tight sandstone reservoirs.