LOGGING EVALUATION FOR CAVE- AND PORE-TYPE LIMESTONE RESERVOIRS IN TAHE OILFIELD

The Ordovician lithology in the Tahe oilfield is characterized mainly by grainy minicrystal and shale minicrystal limestones, whose reservoir space types are various and unevenly distributed with strong heterogeneity, which make reserving and penetrating mechanisms and reservoir characteristics complicated. Aimed at the complex oil and gas reservoirs, the paper researched reservoir space types, analyzed and described the logging response features of various reservoir space types, applied imaging logging and conventional logging methods to recognize pore-, cave- and fracture-type reservoirs and classified the reservoirs in combination with geologic and core data, and established logging recognition patterns, evaluation standard and reservoir parameter computation methods for various carbonate reservoirs. Through a lot of studies on tackling key problems for many years, this study improved the model for cave- and fracture-type reservoirs recognition by using the integrative probability method, and established a foundation for reserves parameter computation and a trial study on using logging technique to detect fluid properties of cave- and pore- type reservoirs in limestone formation in the Tahe oilfield, and this model has been proved to be significantly practical for the actual production.