RELATIONSHIP OF FORMATION FLUID AND HYDROCARBON IN TAZHONG LOW UPLIFT OF THE TARIM BASIN

The Tazhong low uplift is considered to be in good preservation condition through analyses of salinity,water types and geochemistry exponents of formation water.The centers of high salinity,positive and negative geochemistry exponents match with hydrocarbon distribution very well in Carboniferous and Ordovician layers except Silurian.Carboniferous layer in the southeastern Tazhong and Ordovician layer in structural belt I in the northern slope of Tazhong are both favorable for preservation.Hydrocarbon migratory directions in both formations are related to hydrodynamic force.The former is from northwest to southeast affected by gravity flow while the latter is from northeast to southwest due to compaction flow.The relationship between salinity,geochemistry exponents and hydrocarbon accumulation is tight for the Tazhong low uplift.Beneficial geochemistry exponents of formation water inClude:1) salinity(35 g/L);2) r_Cl^-/r_Mg²⁺-r_Na⁺/r_Mg²⁺(0);3) r_Ca²⁺/r_Mg²⁺(1);4) r_Na+/r_Cl^-(0.9);5) r_SO2-₄×100/(r_Cl^-+_SO2-₄)(3);6)(r_HCO^-₃+r_CO^2-₃)/r_Ca²⁺(0.2).