IDENTIFICATION OF CARBONATE ROCKS PETROPHYSICAL TYPES WITH NUCLEAR MAGNETIC RESONANCE EXPERIMENTS DATA TAKING INTO ACCOUNT THEIR LITHOLOGICAL CHARACTERISTICS

The relevance. Significant part of world hydrocarbons reserves is confined to carbonate reservoirs, which are characterized by complex structure of voids. Reserves estimation and development design of such reservoirs require detailed study of porous media structure, that directly influences the reservoir properties. Identification of petrophysical rock classes is an integral part of hydrocarbons reservoir petrophysical model building. Nuclear magnetic resonance (NMR) method is one of the methods of rock porous structure research and has a number of advantages over other methods. However, there is no information in the published literature about application of this method for petrophysical typing. The results of petrophysical classes identification based on integration of NMR experiments and thin sections description data enhance the quality of reservoir geological and hydrodynamic simulation and hence improve accuracy of hydrocarbons reserves estimation and efficiency of field development. The main aim of the research is carbonate rock petrophysical typing based on integration of NMR experiments and thin sections description data, and estimation of classes identification accuracy with the methods of mathematical statistics. Object: carbonate rocks of Mishrif formation, which is productive in the field of Mesopotamian oil-and-gas province. Methods: analysis of core sample NMR experiments results, thin sections description and routine core analysis, methods of mathematical statistics. Results. Three petrophysical rock types are identified in the log of the well, which intersects productive deposits. The types are: 1st class (wackestone and wackestone/floatstone rock structure), 2nd class (packstone, grainstone and rudstone rock structure) and 3rd class (framestone rock structure). These petrophysical classes are proved with statistical analysis results.