Matrix porosity calculation in volcanic and dolomite reservoirs and its application
Li Ning1,2, Wu Hong-Liang1, Feng Qing-Fu1, Wang Ke-Wen1, Shi Yu-Jiang3, Li Qing-Feng4, and Luo Xin-Ping5
1. Research Institute of Petroleum Exploration & Development, PetroChina, Beijing 100083.
2. College of Geophysics and Petroleum Resource, Yangtze University, Jingzhou, 434023.
3. Changqing Oil Field Research Institute, Xian, 710016.
4. Daqing Logging Company, Daqing, 163453.
5. Xinjiang Oil Field Research Institute, PetroChina, 834000.
Abstract：
Matrix porosity calculations of fractured and vuggy reservoirs, such as volcanics and weathered dolomite, are one of the problems urgently needed to solve in well-log evaluation. In this paper, we first compare the an empirical formula for porosity calculation from full diameter rhyolite core experiments with the matrix porosity formulas commonly used. We discuss the applicability of the empirical formula in fractured and vuggy reservoirs, such as intermediate-basic volcanics and weathered dolomite. Based on core analysis data, the error distribution of the calculated porosity of our empirical formula and the other porosity formulas in these reservoirs are given. The statistical error analysis indicates that the our empirical formula provides a higher precision than the other porosity formulas. When the porosity is between 1.5% and 15%, the acoustic experiment formula can be used not only for acidic volcanics but also in other fractured and vuggy reservoirs, such as intermediate-basic volcanics and weathered dolomite. Moreover, the formula can reduce the effects of borehole enlargement and rock alteration on porosity computation.
LI Ning,WU Hong-Liang,FENG Qing-Fu et al. Matrix porosity calculation in volcanic and dolomite reservoirs and its application[J]. APPLIED GEOPHYSICS, 2009, 6(3): 287-298.
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2009, Vol. 6 
