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ISSN 2394–7799 IJAETCS (2014) Vol.1, No.1, 43-51 Research Article International Journal of Advancement in Engineering, Technology and Computer Sciences COMPARISON BETWEEN UNDERBALANCE AND CONVENTIONAL OVERBALANCE DRILLING IN THE GULFOF SUEZ USING A DRILLING SIMULATOR Taher Elfakharany Al-Azhar University, Faculty of Engineering, Nasr City, Cairo, Egypt (taher.elfkharany@bue.edu.eg) ----------------------------------------------------------------------------------------------------------------------------- ---------- ABSTRACT: The technique used worldwide while drilling is known as overbalanced drilling. Which is defined as the drilling process where the hydrostatic pressure used exceeds the formation pressure. This is done with the main purpose of “killing” the well. However, there are numerous problems that accompany overbalanced drilling. Such problems are differential pipe sticking, loss of circulation, formation damage and other problems. A relatively new technique was introduced, known as underbalanced drilling, where the well is being drilled with a hydrostatic pressure less than that of the formation. Correct and proper execution of such technique eliminates problems associated with overbalanced drilling. More precisely, underbalanced drilling solves the issues of formation damage, differential pressure sticking and loss of circulation. Additionally, underbalanced drilling increases the rate of penetration and provides other uses discussed in this paper. On the other hand, underbalanced drilling has its own problems as well. The objective of this paper was divided into three steps; the first step involves collecting and filtering the data required for comparing between overbalanced and underbalanced drilling using the drilling simulator. The second step is running the data on the simulator, and analyzing and discussing the output. Finally, it can be concluded that UBD provides lower drilling costs, increased ROP and less hole problems when it was compared to overbalanced drilling of the same formations. KEYWORDS: Underbalanced Drilling (UBD), Overbalance Drilling (OBD), Simulator, Equivalent circulating density (ECD), Daily Drilling Report (DDR), Total Flow Area (TFA). ----------------------------------------------------------------------------------------------------------------------------- ---------- 1. INTRODUCTION: Throughout time, the petroleum industry witnessed vast advancements and evolutions and still does. The vitality of the presence of hydrocarbons (oil and natural gas) in everyday lives dictates the commitment that has to be made towards the petroleum industry. Consequently, the latter became one of the most important industries in modern day life. Drilling problems are inevitable and there is no drilling operation throughout the world that occurs without encountering problems. Such problems may be related to the equipment being used, difficulties met within the well, human errors or accidents. Naturally, any problems or accidents might have fatal as well as economical consequences. An ideal drilling operation is one where there are no problems faced, hence no additional time and cost requirements and no life threats [(1), (2)]. Therefore, it can be deduced that drilling engineers aim to achieve optimum drilling operations with the least time and costs possible. To achieve this, researches are being conducted globally to tackle tedious problems associated with drilling. The solutions may be in the form of drilling equipment modifications and chemicals or introduction of new drilling techniques and new equipment designs [(3), (4)]. A relatively new drilling technique was introduced, called underbalanced drilling (UBD). Proper design and execution of a UBD operation can prevent or minimize the problem of fluid invasion and its outcomes (clay reactions, precipitation, and emulsification), along with invasive formation damage that result during conventional overbalanced conditions. 1.1. PROBLEM STATEMENT: This paper deals with problems associated with overbalanced drilling that are solved by underbalanced drilling. In other words, the advantages of underbalanced drilling and how problems pertinent to Elfakharany, T./International Journal of Advancement in Engineering, Technology and Computer Sciences, Vol.1, No. 1 44 overbalanced drilling are solved or tackled by underbalanced drilling. The objective of this paper is to make use of a drilling simulator to correlate between overbalanced and underbalance drilling. 1.2. REVIEW OF THE DIFFERENCES BETEEWN OVERBALANCE AND UNDERBALANCE DRILLING: The major difference between conventional overbalanced drilling and underbalanced drilling is the hydrostatic pressure exerted by drilling fluids in each technique.

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