Sharif Digital Repository

Nowadays, one of the most major problems in drilling industry is Lost Circulation in different formations. Lost Circulation increases non-productive time, expenditures and environmental damages. Lost Circulation can happen in natural or induced fractures, cavernous formations and high permeable rocks and it can be subcategorized in seepage, medium, severe or complete type based on the severity of the problem. For addressing this issue, different methods are suggested. One of the most considered of these methods is using Lost Circulation Materials (LCM). In this thesis, it was tried to manage the situation with Designing and engineering of lost circulation materials for different lost... 

The purpose of this project is to design a water-based drilling fluid for use in high-pressure and high-pressure conditions (Deep Drilling). This goal is usually achieved by adding the resistant polymers to the ambient conditions (temperature stability) to the drilling fluid (here the blue base fluid), and then the rheological properties of the fluid are studied. The stability of the rheological properties of the fluid in high temperature and high pressure conditions is not constant. In this situation, a sequence of events occurs, for example, decreases with increasing viscosity and turbulence, and hence the reduction of drilling fractures and the efficiency of the bottom of the well is... 

Transport of drilling cuttings at the bottom of the well has always been one of the common problems of oil and gas drilling, which causes stock pipe or reduce the penetration rate and other problem. For this reason, the design of drilling fluid is one of the important drilling problems to be considered in order to optimally transfer drilling cuttings to surface. So far, many papers have been devoted to optimizing the drilling fluid for the transport of cuttings, but these papers focus on the state of drilling fluid static and less to model the dynamics and to examine the interaction between the cuttings and drilling fluid. At this end this study will modeling the drilling fluid flow using... 

Underbalanced drilling is a type of drilling operation in which the pressure of the drilling fluid is less than the pressure of the formation. This pressure difference has created advantages for this method. Less formation damage, reduction of pipe stuck, increasing rate of penetration and production during drilling are the advantages of this method compared to traditional methods. To reduce the pressure of the drilling fluid, very low density fluids should be used. One way to reduce density is to mix a compressible fluid such as gas into water. Due to the difference in density and surface tensile strength of water and gas, these two phases do not combine, so a stable combination of these... 

Drilling fluid is one the most important part of drilling operations in the oil and gas wells digging. From an economic point of view, almost 25 to 45% of drilling costs are allocated to drilling fluid. Drilling fluids consist of several components with different physical and structural forms which can be assumed as complex fluids. Optimum performance of the drilling process could be obtained through the dynamic fluid computation which requires a reliable mathematical model capable to predict transient-state and steady-state rheological behavior of drilling fluid. Generalized Newtonian models, such as the Bingham-plastic model, the power model, and the Herschel-Bulkley model, are the most... 

Aphron drilling fluids or CGA fluids are the wellknown updated drilling fluids in recent years.this kind of drilling fluids can control the mud loss into the formation and thus reduce formation damage and drilling costs. its structure consists of two phase fluid (gas and liquid) that the aphrons are the micro bubbles with 10 to 100 micrometer diameter that have strong stability in liquid phase compared to foamy drilling fluids. Generally aphron drilling fluids are made of base drilling fluid and surfactants, for more stability, mixed surfactant-polymer additive is so beneficial. in the last two decades, the Lattice-Boltazmann method is introduced for computational fluid dynamic area and... 

One of the most important challenges in drilling horizontal and directional wells is the optimization of hydraulics and hole cleaning and ECD management. In these wells, poor hole cleaning can lead to formation of cutting bed on the low side of the annulus and cause problems such as stuck pipe or increase in torque and drag. Also poor hydraulic design can lead to decrease in rate of penetration and thus, increase in costs. Mud weight should be placed inside the range of mud window (more than pore pressure and less than formation fracture pressure) in order to prevent kick of reservoir fluid or mud loss.In this thesis, the main goal is to optimize hydraulics and hole cleaning and manage ECD... 

Currently, drilling such as vertical or straight-hole drilling, i.e. usually less than 30 degrees inclined, or deflection drilling is used to drill at conventional and even unconventional reservoirs around the world to increase recovery factor and productivity. A major challenge is cleaning the hole or removing debris which if not done properly can lead to problems such as stuck pipes. In addition, Improper use of drilling fluid in terms of rheological properties in different stages of drilling operations can cause the well to collapse due to the accumulation of particles in the annular space. The transfer speed of particles is very important in cleaning the well. Inefficient cleaning of... 

One the basic challenges during drilling of both vertical and horizontal wellbores is due to mud filtrate invasion into the formation. Addition of nanoparticles to composition of drilling fluid has been recognized as a measure of control and reduction of filtrate invasion. Despite notable advances in formulation of nano-enhanced drilling fluids, effects of surface wettability of nanoparticles on their performance have not been studied with any precision. Moreover, return permeability of a grain packed porous media after extreme invasion by mud filtrate has not been experimentally measured in a radial system, yet. The last but not least, Generation and development of mud cake opposite the... 

Constant drilling in the shale formation causes many problems such as shale swelling and well instability. Annually many costs are spent dealing with these problems in the drilling industry. Many factors can affect this issue. The most important factor is the type of drilling fluid and its additives. The use of oil-based mud is the best option to deal with the clays instability but, due to environmental problems resulting from OBM, their use has been banned in most parts of the world. Therefore, the water-based mud is the only option for the oil industry that can modify its property by use of additives. In this study, the muds contain Nano silica have been introduced. Silicate as shale...