Sharif Digital Repository

Oil field industry is one of the most challenging engineering subjects. In oil well drilling, undesired motion could raise a lot of problems such as stuck pipes; wash out pipe, and etc. In this industry, motion prediction is very important because a good prediction can avoid instruments failure and as a result considerable amount of time could be saved. Predicting dynamic characteristics of drill-string such as whirl orbit, whirl speed, and axial, lateral, and torsional displacements, accelerations, and velocities, might be useful in avoiding or decreasing failures. A program based on FEM (Finite Element Method) is developed in MATLAB considering deviation of drill-string, contacting with... 

In this thesis we employ finite elements and conjugate gradient methods to exibit a numerical solution for governing equations of borehole stability  

Economical strategy of developed countries imposes to improve energy efficiency and a rational renewable energies usage in the buildings. Ground source heat pumps are one of the most important tools in the way moving toward this goal. This study focuses on studying the effect of applying different refrigerants in the direct expansion ground source heat exchangers. In order to compare the performance of the ground source heat pumps using different refrigerants, a specific methodology is presented and implemented. First on this study, the thermal performance of a geothermal borehole filled with both CO2 and a zeotropic mixture of CO2 and R32 (20/80) is studied and the quality, temperature, and...