A Research Of Logging Evaluation For Carbonate Reservoir In Tahe Oilfield

Hydrocarbon pool forming conditions are good in ordovician fractured carbonate reservoir of Tahe Oilfield. However, as the result of deep burial, different types, great variation, complex distribution and strong diagenesis of reservoirs, different types of oil and gas pools are formed, which causes great trouble for exploration and development of this oilfield. This paper, based on the characteristic of fractured carbonate reservoir and the main problems encountered in fractured reservoirs of Tahe Oilfield, establishes a set of practical identification and evaluation methods of logging responses for fractured carbonate reservoirs by combining theory and field studies.The lithology of carbonate reservoirs in researched region is complex. By processing and analyzing mass petrophysical data, the characteristic of parameters in Archie Equation is studied, lithology is identified and pore types are researched.With analysis of the responses of conventional log and image log in this region, according to the pore types, reservoirs are divided into four types, also with their respective identification methods.Besides, by using 3-D finite element algorithm, dual laterolog responses of single fracture, fracture group, crossed fracture and fractured formation with macro anisotropic medium under any dip conditions are computed. Further more, the abnormal responses of fracture on different logging curves are analyzed, thereby realizing the recognition of fracture zone and determination of fracture development zone for qualitative identification. By dividing fracture into different types, logging response models for each are established. Then fracture porosity and permeability, formation water saturation, shale volume and total porosity are computed. According to storage types of formation, the probability of identifying fluid property by adopting cross plot of logging data is researched. The main part is the discussion of the limitation for cross plotting of logging data and results from its simple computation, in order to identify fluid property. Meanwhile, novel methods are also applied in fluid identification.Because of the complex lithology and great anisotropy of fractured reservoir in Tahe Oilfield, conventional log, accompanied with novel techniques and methods, is used to establish logging interpretation models for different fractures, and study evaluation methods suitable for this oilfield.