Отправлено: 03.08.15 10:43. Заголовок: Establishment and application of logging saturation interpretation equation in vuggy reservoirs

Sun Wen-Jie, Li Ning, Wu Hong-Liang, Wang Ke-Wen and Zhang Gong

Establishment and application of logging saturation interpretation equation in vuggy reservoirs
APPLIED GEOPHYSICS, Vol.11, No.3 (September 2014), P. 257-268

Abstract: Vuggy reservoirs are the most common, albeit important heterogeneous carbonate
reservoirs in China. However, saturation calculations using logging data are not well
developed, whereas Archie method is more common. In this study, electrical conduction in
a vuggy reservoir is theoretically analyzed to establish a new saturation equation for vuggy
reservoirs. We found that vugs have a greater effect on saturation than resistivity, which causes
infl ection in the rock-electricity curve. Using single-variable experiments, we evaluated the
effects of vug size, vug number, and vug distribution on the rock-electricity relation. Based
on the general saturation model, a saturation equation for vuggy reservoirs is derived, and the
physical signifi cance of the equation parameters is discussed based on the seepage–electricity
similarity. The equation parameters depend on the pore structure, and vugs and matrix pore
size distribution. Furthermore, a method for calculating the equation parameters is proposed,
which uses nuclear magnetic resonance (NMR) data to calculate the capillary pressure curve.
Field application of the proposed equation and parameter derivation method shows good
match between calculated and experimental results, with an average absolute error of 5.8%.
Keywords: Vuggy reservoir, saturation, general solution saturation equation, capillary
pressure, capillary pressure curve, NMR, rock electricity