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Comparison among Models Which Estimate Minimum Horizontal Stress and its Methodology
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, EAGE Workshop on Geomechanics in the Oil and Gas Industry, May 2014, cp-397-00028
- ISBN: 978-90-73834-86-6
Abstract
Minimum horizontal stress is a key input parameter for many rock physical models – Hydraulic fracturing, lateral well design, wellbore stability etc. Inaccurate stress magnitudes might not provide the sensitivity necessary to determine the stress barriers above and below pay zones. Full evaluation of the multiple models assists to ultimately provide better understanding fracture network. Static and dynamic mechanical core properties were measured in several places along the length of a vertical core in an unconventional shale reservoir. The properties include Young’s modulus, Poisson’s ratio, ultrasonic compressional/shear acoustic velocity and the Mohr failure parameters of friction angle and cohesion, stiffness parameters and Biot coefficients. Utilizing the determined mechanical properties the minimum horizontal stress (Sh) was estimated using the following models Ben Eaton – isotropic and anisotropic, modified Ben Eaton with correction factor, Vernik, Jaeger and Cook, Hubbert and Willis, Thiercelin – MC envelope and stiffness tensors (Cij), Segall and Penebaker An isotropic/anisotropic comparison was completed to better understand the amount of anisotropy. Software has been developed to enhance the process of determining in-situ stresses and evaluate the effects of various parameters affecting the calculation such as estimated gradients and Biot assumption. The focus of this presentation is to calibrate vertical sonic logs (Vp0, Vs0) using core data, determine three independent pseudo velocity logs (Vp45, Vp90 and Vs90), obtain dynamic to static correlations necessary to develop an estimated continuous anisotropic mechanical stress profile.