Log and multiwell evaluation of carbonate reservoir in the Tahe oilfield

Conventional log data is mostly used in identifying low-porosity formation where fracture and hole both are great in a larger segment. Because of the lower resolving a bility of conventional log, it is difficult to identify fracture formation or low-porosity zone naturally. For micro-fracture and corroded micro-pore reservoir, conventional log is impossibility to identify them directly. In order to use conventional log to identify efficiently reservoir types with different pore, cave and fracture features, we must study conventional log response of pore, fracture and cave and enlarge them.The primary work is to study the log sensitivity to different reserve space. According to the carbonate reservoir’s character of Tahe oilfield in Tarim basin. Xinjiang, using conventional log data ratio-computing and o verlapping technologies, this paper pick up reservoir’s classification character parameters:Crock resistivity parameters, ratio of caliper Kl, ratio of deep to shallow resistivity K2,ratio of relative spontaneous K3;Porosity parameters, ratio of acoustic wave time difference K4,ratio of density K5,neutron relative porosity K6;Energy spectrum parameters, relative content of uranium K7, ratio of thorium to uranium K8. Then synthesis estimation is carried out and the criterion of determining reservoir types is established used them in formation distinguishing and reservoir identifying.This work broadened the applying area of conventional log data.The effect is very evident.