ABSTRACT: Inverse analysis is commonly used in identifying geomechanical parameters based on the monitored information such as displacement or stress. Conventional inverse analysis method is incapable of recognizing non-linear relationship involving displacement, stress and mechanical parameters effectively. A hybrid model which combined Multi-output-Support Vector Machine (MSVM), Artificial Bee Colony (ABC) and numerical analysis has been proposed to estimate the in situ stress and rock mechanical parameters based on borehole fluid pressure. MSVM is used to represent the non-linear relationship between parameters of numerical model and borehole fluid pressure. ABC is used to search the set of unknown recognized parameters based on the objective function. Numerical analysis of hydraulic fracturing is used to create the necessary training and testing samples for the hybrid MSVM-ABC model. Results of numerical experiments demonstrate that a hybrid MSVM-ABC model for inverse analysis can effectively identify in situ stress and rock mechanical parameters based on wellbore fluid pressure in the hydraulic fracturing process. 1 INTRODUCTION Geomechanical parameters such as Young's modulus and in situ stress in the field of petroleum are important to reservoir simulation, borehole stability analysis and production of petroleum (Gokceoglu et al. 2004, Juliusson 2012). However, it is difficult to obtain those parameters accurately and efficiently using the traditional laboratory test and in-situ test because of the complex, nonlinear and uncertainty of rock mass characters (Zhao & Yin 2009). Inverse analysis method provides a good way to get these parameters by combining the field-observed information with numerical simulation. Inverse analysis are commonly used in rock mechanics and engineering such as tunnel, underground engineering and rock slope etc (Sakurai & Takeuchi 1983, Gioda & Maier 1980, Miranda et al. 2011, Feng & Hudson 2011). In the petroleum industry, hydraulic fracturing is the most common technique to perform well stimulation and earth stress characterization of hydrocarbon reservoirs, especially for unconventional reservoirs such as shale gas, tight gas and coal bed methane. In this paper, geomechanical parameters were estimated by combining inverse analysis and hydraulic fracturing test.

ABSTRACT: Taking square red sandstone samples as study objects, both destruction properties and destruction development model were analyzed with self-designed shear creep experimental device of coal or weak rock and monitor software of coal or rock micromechanics properties under restrictive shear creep. The results show: development process of red sandstone destruction under restrictive shear creep was show in process that first formed main rupture plane, then formed micro-cracks area near the main rupture plane, rupture plane was formed and burst destruction occurred in finally, and accompanying with a large crack voice. Development process of destruction model was show in progressive model but destruction model was shown in burst model, the rupture plane was non-flat and non-smooth wavy plane. 1 INTRODUCTION Obvious slip plane appeared and accompanied with significant slip trace after most of landslide slip instability occurred, shown in Figure 1. Obvious slip plane and significant slip trace were formed in the process of growth and development of slope slip through continuing overcoming cohesion in rock or soil and friction on slip plane. And all of state of stress, properties of rock or soil and change of external conditions near slip plane can affect growth, development and forming of slope slip plane. Therefore, analyzing and obtaining state of rock stress near slip plane, and researching mechanical evolution properties of rock under above state of stress, which were key important fact for obtaining the growth process properties of slope slip and preventing of slope destruction occur. Based on comprehensive analysis of many slopes, the conclusion that these rock near slip plane can be taken as in state of restrictive shear creep is obtained, restrictive shear creep load comes from the weight of overlying rock or soil of slip plane, direction of shear creep is slip direction of slip plane, restrictive effect is shown in addition of friction on slip plane because of the weight of overlying rock or soil of slip plane, simplified model is shown in Figure 2.