Rock Mechanics
Mohammad Shekari Nejad; Mohammad Fatehi Marji; Manouchehr Sanei
Abstract
The slope geometry, rock mass quality, groundwater level, and geological features of the mine mainly influence the slope stability of an open-pit mine. In this study, the stability analysis of the open pit slope under the influence of various factors was studied. The analysis was conducted based on data ...
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The slope geometry, rock mass quality, groundwater level, and geological features of the mine mainly influence the slope stability of an open-pit mine. In this study, the stability analysis of the open pit slope under the influence of various factors was studied. The analysis was conducted based on data collected from the Golgohar iron ore mine in Sirjan. To build the numerical model, first, the geomechanical and hydrogeological parameters of the mine were determined using laboratory and field tests. Then, numerical models of slope stability were built based on the finite difference method using hydromechanical coupling analysis. The real characteristics in these models include lithology types, variations in geomechanical properties, groundwater level, and real slope geometry. Numerical models were built based on three different conditions, including a model in dry conditions, a model considering the groundwater level, and a model after the drainage process. The results show that the whole slope angle of the mine that has the highest safety factor is 36 degrees. In addition, the groundwater level reduces the safety factor of slope stability compared to dry conditions, and the drainage process can increase the safety factor of the mine wall. In all three conditions, the whole slope angle of 36 degrees has the highest safety factor. Therefore, it is suggested that the whole slope angle be considered to increase the safety factor and reduce the stripping ratio to increase the profitability of the open pit mine.
Rock Mechanics
Masoud Yazdani; Mohammad Fatehi Marji; Mehdi Najafi; Manouchehr Sanei
Abstract
Around 70% of the world's hydrocarbon fields are situated in reservoirs containing low-strength rocks, such as sandstone. During the production of hydrocarbons from sandstone reservoirs, sand-sized particles may become dislodged from the formation and enter the hydrocarbon fluid flow. Sand production ...
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Around 70% of the world's hydrocarbon fields are situated in reservoirs containing low-strength rocks, such as sandstone. During the production of hydrocarbons from sandstone reservoirs, sand-sized particles may become dislodged from the formation and enter the hydrocarbon fluid flow. Sand production is a significant issue in the oil industry due to its potential to cause erosion of pipes and valves. Separating grains from oil is a costly process. Oil and gas companies are motivated to reduce sand production during petroleum extraction. Hydraulic fracturing is one of the parameters that can influence sand production. However, understanding the complex interactions between hydraulic fracturing mechanisms and sand production around wellbores is critical for optimizing reservoir recovery and ensuring the integrity of production wells. This article explores the integrated simulation approach to model hydraulic fracturing processes and assess their effects on sand production. Two-dimensional models were created using the discrete element method in PFC2D software for this research. The fractures' length in the models varies based on the well's radius. The angle between two fractures at 90 and 180 degrees to each other was also modeled. In the first case, the length of the fracture is less than the radius of the well, in the second case, the values are equal and finally, the fracture length is assumed to exceed the well radius. The calibrated and validated results demonstrate the change in sand production rate in comparison to the unbroken state.
Rock Mechanics
Masoud Yazdani; Mohammad Fatehi Marji; Hamid Soltanian; Mehdi Najafi; Manouchehr Sanei
Abstract
Approximately 70% of the world's hydrocarbon fields are located in reservoirs with low-strength rocks such as sandstone. During the production of hydrocarbons from sandstone reservoirs, sand-sized particles may become dislodged from the formation, and enter the hydrocarbon fluid flow. Sand production ...
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Approximately 70% of the world's hydrocarbon fields are located in reservoirs with low-strength rocks such as sandstone. During the production of hydrocarbons from sandstone reservoirs, sand-sized particles may become dislodged from the formation, and enter the hydrocarbon fluid flow. Sand production is a significant issue in the oil industry due to its potential to cause erosion of pipes and valves. Separating grains from oil is a costly process. Therefore, oil and gas-producing companies are motivated to reduce sand production during petroleum extraction. Various methods exist for predicting this phenomenon including continuous, discontinuous, experimental, physical, analytical, and numerical methods. Given the significance of the subject, this research work aims to achieve two primary objectives. Firstly, it proposes a two-dimensional numerical model based on the discrete element method to address the issues of high strain and deformation in granular materials. This method is highly reliable in simulating the mechanism of sand production in oil wells. Secondly, the production of sand is influenced by two factors: fluid pressure and stress; to evaluate changes in production from a particular reservoir, it is necessary to analyze each parameter. Two sandstone samples, similar to reservoir rock conditions, were prepared and tested in the laboratory to demonstrate sand production phenomenon. The numerical results have been verified and compared to their experimental counterparts.
