| Carbonate reservoirs play an extremely important role in oil and gas production in the world, and they
contribute about 60% of the world's oil and gas production. As the development of widespread continental clastic
reservoirs in China comes to the late stage, the Chinese petroleum companies pay more attention to overseas marine carbonate reservoirs. Compared with clastic reservoirs, carbonate reservoirs are always in the spotlight because of their complexity and strong heterogeneity. Influenced by sedimentation, tectonism and differential diagenesis, there are many
difficulties of the Carboniferous carbonate reservoirs in North Truwa Oilfield, Kazakhstan in lithology identification, reservoir parameter calculation and fluid property identification due to complex lithology, diverse pore structure, poor matrix physical properties and complex logging response. In view of the problems existing in the logging evaluation of
complex carbonate reservoirs in this oilfield, based on a large number of core observation and thin section analysis, the
mineral components of this kind of reservoirs are reliably identified through the carbonate optimization processing method, and then the lithologic profile is calculated. Combined with imaging logging data, the dual medium interpretation model of pore and fracture is established to realize the quantitative characterization of complex carbonate reservoir, effectively depict the spatial type and connectivity of reservoir, and identify and classify various pore types. According to the combination characteristics of reservoir space and the relationship between porosity and permeability, the reservoir is divided into five types: hole-fracture, fracture-pore, pore, hole and fracture. The logging evaluation on the reservoir classification improves the interpretation accuracy of reservoir physical property, which provide reference for reservoir productivity prediction, qualitative and quantitative reservoir evaluation method and the theory research. A set of relatively perfect logging evaluation method for complex carbonate reservoir is obtained, which has guiding significance for logging evaluation of similar reservoir in littoral Caspian Basin and other areas. |
