Accurate description of the porosity and permeability distributions are the key for reservoir performance predictions. The porosity of the formation can be evaluated from the cores and/or well logs while the permeability is usually determined from the cores and/or well tests. Usually cores and well test data is often abundant Therefore, the evaluation of permeability and porosity distributions from well log data in heterogenous formation represents a significant technical as well as economic advantage. However, the evaluation of permeability from well log data represents a difficult and complex problem in heterogenous formation.

The goal of this study has been to develop a methodology for determining porosity and permeability distributions in a heterogeneous formation utilizing geophysical well logs. Granny Creek Field in West Virginia has been selected as the study area in this paper. This field has produced oil from Big Injun Formation since early 1900's. The water-flooding operation was initiated in 1970's and currently is in progress. Well log data are available on substantial number of wells. Core samples are also available from a few wells.

Core samples and the well logs were analyzed to determine permeability, porosity, and water saturation. In addition, the results of core analysis and well log interpretations were complemented by geological information and initial production data to develop a correlation between permeability, porosity, water saturation, depositional environment, and pore type. The results were employed for development of porosity and permeability distributions. The methodology presented in this paper could serve as a guideline for correcting permeability with other rock parameters in heterogenous formations. The complexity of such correlations is directly proportional to degree of heterogeneity of the formation.

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