B Tokhmechi; H Azizi; H Memarian
Abstract
Estimation of rock type, porosity and saturation are the main applications of petrophysical logs. Several equations are presented for mentioned estimations, and deficiencies of these equations are widely investigated. In this paper, general deficiency of well logs processing methods is discussed. In ...
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Estimation of rock type, porosity and saturation are the main applications of petrophysical logs. Several equations are presented for mentioned estimations, and deficiencies of these equations are widely investigated. In this paper, general deficiency of well logs processing methods is discussed. In general, because of smoothing trait of estimators, variability of estimated data is less than raw data. Since rock type, porosity and saturation are estimated from various well logs, it is anticipated that they have less variability in comparison with raw well logs. Therefore, it seems that energy (equal to information) of Fourier transform of estimated well logs in low frequency bands have to be more than similar energy of raw well logs. This study has been done on raw and estimated well logs of more than 100 wells of Iranian south and southwest oil fields. The results showed that estimated well logs have more variability, which confirms a fundamental deficiency in current well log processing methods.
H Azizi; H.R Siahkoohi; B Evans; N Keshavarz Frajkhah; E Kazemzadeh
Abstract
Rock physics is the major tool to describe physical property of reservoir rocks; such as porosity, permeability, degree of saturation, property fluid that saturated, shape of pores, compressibility and etc via studying ultrasonic wave transmitting through a rock sample.
Between these parameters, porosity ...
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Rock physics is the major tool to describe physical property of reservoir rocks; such as porosity, permeability, degree of saturation, property fluid that saturated, shape of pores, compressibility and etc via studying ultrasonic wave transmitting through a rock sample.
Between these parameters, porosity and degree of saturation are more effective on elastic wave velocities which have been studied extensively in recently years. Amplitude of acoustic waves is a function of acoustic impedances (velocity and density) could be used to study lithology, pore fluids and saturation. In this paper we studied how main characters wave (velocity, amplitude, frequency) changes related to two main reservoir characteristics (pore pressure and confining pressure). In our study, we transmitted ultrasonic waves in different frequencies through a sandstone core in reservoir pressure condition. Analysis confirmed that similar to previous studies, amplitude of transmitted signal is a more sensitive attribute to pressure changes rather than velocity of the waves.