Static Young's modulus model prediction for formation evaluation

Abstract

Accurate estimation of rock mechanical properties such as the static Young modulus is critical to reduce the risks associated with exploration and production activities. Ideally, the determination of the rock static Young's modulus will require experimental studies to be conducted on core data taken from the formations of interest. When core data are not available (possibly due to economic reasons), the static Young's modulus is often estimated from the dynamic Young's modulus using empirical relationships, since the dynamic Young's modulus can easily be obtained from the petrophysical data. The higher the formation porosity, the greater the difference between the static and dynamic Young's modulus. The existing empirical relationships are lithology specific and they are suitable over the porosity range from which they have been derived. Therefore, the generalization of these relationships may produce erroneous results. To be applicable to various lithologies and porosity ranges, a new relationship between the static and dynamic Young's modulus is being proposed. The new model incorporates a lithology-porosity dependent parameter. The model is purely empirical, based on the analysis of extensive laboratory data obtained from the literature. Comparisons are then made with the existing relations using statistical analysis. The results show that the newly proposed model outperforms all previously established models.