Sharif Digital Repository

The mud loss and its impact on the formation play a vital role in the productivity of the formation and the near wellbore area. Despite the importance of the use of mud during the drilling process, one cannot overlook the issues that may be caused by losing mud into the formation. In addition to the formation damage caused by mud loss, the cost associated with such phenomenon and drilling operational issues and challenges has motivated the industry to look into different avenues to resolve the mud loss issue or reduce its impact. Evaluating the impact of such a phenomenon on these issues requires accurate modeling. In this study different models have been developed to evaluate the impact of... 

The purpose of drilling is to create a safe path to access underground hydrocarbon resources. Therefore, during drilling operations, barriers should be considered to ensure the safety of the well. When drilling a well, if for some reason, brine, gas or oil enter the well, the pressure of the mud column decreases, which will continue to collapse the stability and integrity of the well. In this case, the external fluid may reach the wellhead and blowout. For this reason, blowout preventers should be installed at the wellhead to secure the well with high confidence by closing the valves and preparing for the continuation of the drilling process. Well blowout may lead to loss of personnel lives,... 

Hydraulic fracturing, as an industry-leading technology, has proven to be very efficient in increasing the productivity of oil and gas wells. Therefore, this technology has been taken into attention in recent years and the number of hydraulic fracturing operations has been increasing. In order to enhance the efficiency of this technology, the final transmissibility of the fracture needs to be at the maximum possible value. To do so, proppant injection is the most common way to maintain a fracture open. To achieve a successful hydraulic fracture operation, detailed knowledge of the particle's transport and distribution inside the fracture is needed.In this study, a static fracture geometry... 

There is many operational problems in the drilling industry. One of these basic problems is stuck pipe. This problem occurs with different intensities in different formations due to particles falling into the well, pressure difference in the formation and drilling mud and instability of the wellbore and creates conditions in which the drilling string can neither rotate nor move, so all Drilling operations are stopped so that according to studies, pipe sticking is one of the most important reasons for stopping drilling operations. This stop imposes millions of dollars of operational damage on oil services companies annually. Therefore, identifying and prediction of stuck pipe as a major... 

Due to environmental concerns about fossil fuels energy sources, countries are striving to replace fossil fuels with renewable energy sources. However, most alternative energy sources are highly dependent on weather and seasonal conditions. Underground hydrogen storage (UHS), unlike carbon dioxide storage which only experiences the gas injection phase, involves injection and production cycles. Therefore, it faces different challenges, each of which has different effects on the final hydrogen recovery rate and, consequently, cost estimation. Some of the major challenges ahead include the reservoir structure, heterogeneity of reservoirs, selection of suitable cushion gas, the impact of the... 

Diagnostic Fracture Injection Test (DFIT) uses to identify the characteristics of the reservoir, including minimum horizontal stress, permeability, initial reservoir pressure, etc. The general steps of this process include fluid injection, fracture initiation in the matrix, fracture propagation and its closure due to fluid leak-off. The results of DFIT are analyzed in two stages based on the fracture closure event. The objective of this study is to investigate the effect of leak-off mechanisms on pressure-dependent leak-off (PDL), tip extension and fracture storage. To do so, different methods are used for identifying the cooperating parameters at each step. In order to analyze DFIT, a... 

Hydrogen storage in porous subsurface formations, such as aquifers or depleted hydrocarbon reservoirs because of their high storage capacity, has gained momentum as a promising approach to balance the renewable energy supply and demand. However, the poor understanding of hydrogen flow dynamics in porous media is the main obstacle to the development and widespread application of underground hydrogen storage (UHS). For example, the main uncertainty is lack of detailed understanding of hydrogen flow dynamics in the natural porous media which leads to the unknown volume of recoverable hydrogen for this cyclic process. In this research, by developing a visual microfluidic apparatus to handle... 

Production of solid particles is a phenomenon that occurs in most oil and gas well. This phenomenon can cause many problems in every life stage of a well such as erosion of surface equipment, subsurface equipment and environmental problems associated with solid particles disposal. On the other hand, this phenomenon can increase the permeability of near wellbore areas, which is considered to be the advantages of solid particles production. In this study, nine sandstone samples were prepared and different pressure ratios have been used for evaluation production of sand in different situations. Also, in the next step, by numerical simulations, studies of stresses around a well and... 

This paper decomposes the saving rate into cohort, age and year effects. This objective is accomplished by constructing a pseudo-panel that amalgamates nineteen consecutive, cross-sectional Household Income and Expenditure Surveys from 1991 to 2009. To construct year-of-birth cohorts with consistent composition over time, analyses are limited to those born between 1926 and 1975. Results reveal that those belonging to younger cohorts save a higher fraction of their income relative to their predecessors at the same age. Moreover, the increase in the saving rate can not be explained by the significant decline in household size or rise in educational attainment among younger cohorts. Closer... 

Release of toxic gases and hazardous materials is very dangerous for health of people that presence in near of release places. Whereas if the concentration of some toxic materials is more than a definite limit, it may cause of irreparable hurt to health of people in very short times, hence reduce the concentration of released materials can get the time for refuge in safe sites for people that presence in released site in initial times.
In this paper with use the Computational Fluid Dynamics models the effect of fence in reduce the concentration of dense gases and delay the distribution of these gases has been studied. The two toxic gas (chlorine and methyl-isocyanate ) have been... 

Sour Gas is more dangerous than sweet gas because of its hydrogen sulfide contents. So it requires more safety considerations. In this project, the effect of wall thickness and design factor of pipeline on the safe distance was examined by using risk assessment method. The safe distance tables for 4 pipelines with different wall thicknesses and design factors were prepared based on operating pressure, pipe diameter and hydrogen sulfide concentration in gas by using PHAST and PHAST RISK softwares. In this project, the depth of cover parameter was considered in safe distance determination. Also the leak of sour gas was simulated by using... 

In this project, ammonia dispersion in the environment have been investigated and the experimental data have been used in order to show accuracy of calculations. Also, the results of CFD have been compared with the results of PHAST software. The results show that when there is no obstacle in the way of gas release, dispersion models will get good results, but due to existence of the obstacle, their error will be increased to 300%. However, the error resulting from CFD is less than 24% even if there are obstacle there. The effects of obstacle’s distance and height on the dispersion of ammonia gas are investigated. This study showed that the concentration of ammonia increase, when the distance...