Rock Mechanics
S. Ali Madadi; A. Majdi; M. H. Khosravi; A.R. Kargar
Abstract
Fracture mechanics is a vital component involved in studying the exact behavior of rock materials. Detection and assessment of the behavior of rock joints injected by grout plays an important role in numerical modelling in rock mechanic projects. The importance of mechanisms associated with initiation ...
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Fracture mechanics is a vital component involved in studying the exact behavior of rock materials. Detection and assessment of the behavior of rock joints injected by grout plays an important role in numerical modelling in rock mechanic projects. The importance of mechanisms associated with initiation and propagation of cracks due to hydraulic fracturing has led to a considerable interest in investigation and analysis of this phenomenon. In this work, the process of propagation of cracks on the wall of boreholes, drilled in single and bi-material structures, was simulated in ABAQUS software employing the extended finite element method. The energy method was implemented to obtain the stress intensity factor and energy release rate through applying J integral around the crack tip. The method was applied to two rock types, diorite and granite at the Chadormalu iron mine located in the central part of Iran. It was concluded that assuming the same geometry, the possibility of crack propagation at the boundary between two materials was more than the single material medium. Therefore, in dealing with a bi-material medium, if the purpose is to measure the in situ stresses, the measurement should not be performed on the boundary between the two materials.
Rock Mechanics
A. Akrami; M. Hosseini; H. Sodeifi
Abstract
Hydraulic fracturing is used in the oil industry in order to increase the index of production and processing in the wells whose efficiencies have been dropped due to a long-term harvest or the rocks around the wells are of low permeability. Since the hydraulic fracturing operation is costly, it is of ...
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Hydraulic fracturing is used in the oil industry in order to increase the index of production and processing in the wells whose efficiencies have been dropped due to a long-term harvest or the rocks around the wells are of low permeability. Since the hydraulic fracturing operation is costly, it is of special importance to the project managers to determine the pressure required for hydraulic fracturing and the suitable pump for this operation. The numerical modelings used in this work are aimed to investigate the fracture pressure in the carbonate rocks of Bangestan reservoir in Ahvaz, Iran, and to determine a relationship between the pressure required for fracturing and the confining pressure. In this work, unlike the other ones in this field, the developed numerical models had no initial crack or fracture, and the path of the crack and how the crack grows were studied without any pre-determination and presumption. The results obtained show that, in most cases, the crack starts from the central part of the sample, and is extended to its two ends. The crack extension direction was along the borehole axis inside the sample and perpendicular to the lateral stress. The numerical modeling results were well-consistent with the experimental ones, indicating that the pump capacity constraints in the laboratory could be overcome through numerical modelings.
