Sharif Digital Repository

A critical property in designing drilling fluids is the concerns for environmental damages and cost efficiency of mud additives used to complete a well safely and economically. Designing drilling fluids for harsh environments such as high temperature, high salinity formation water, lime and cement contamination demands proper selection of deflocculant (thinner) materials to achieve a successful drilling operation. This study presents a novel thinner material that satisfies the goal of an environmentally and economically acceptable mud in drilling lime contamination areas where drilling carbonate formations with high concentration of calcium ions tends to flocculate clay particles in... 

Vibration is one of the most important factors in design, operation and lifetime of drill string. Evaluation of vibration in the drill string like other rotating machines is very important and according to the length of drill string, whirling is one of the issues discussed. The aim of this thesis is non-linear analysis of the oblique long drill string. By considering the effects of passing drill mud around drill as well as properties of the drilling mud and stick - slip effect in creating whirling. Therefore, the equations related to kinetic and potential energy of a rotating drill string by taking longitudinal and transverse vibrations are written and by using the Lagrange method, equations... 

Since the early 90s, nanotechnology has contributed to several developments in a wide range of Science and industry such as medicine, Physics, Chemistry, Aerospace, electronics and Biology. In recent years, nanotechnology has also made development in the oil and gas industry. The drilling fluid is already one of the most important parts in drilling operation.The physical properties of a mud, rheological properties and minimize fluid invasion into the formation with perfect mudcake are important to assist in optimizing results. Nano-materials as one of the achievements of recent years are effective in achieving these purposes. To obtain the above properties, a variety of polymers as... 

During the drilling of oil and gas wells, the probability of a kick resulting in blow out is high. In the event of a kick, well should be controlled immediately and prevented blowing out. Common methods include: driller method, wait and weight method and concurrent method. In this project, simulation of well control process is done for common well control methods, for water based muds and oil based muds. Movement of different fluids, their combination and removal of fluid from the well are simulated and the results are listed. The flash calculations are done for oil based mud and dissolution of kick fluid in the oil based mud is considered. After simulating and calculating necessary... 

Most used polymers, such as hydrolyzed polyacrylamide, are not able to withstand high levels of salinity and high temperature of the reservoirs. To overcome these problems, in this project, new types of microstructures based on modified acrylamide with hydrophilic groups (malic anhydride monomer) and hydrophobic groups (styrene monomer) using inversible mini-emulsion were synthesized. The structure of the synthesized terpolymer was investigated using methods of FT-IR and 1H NMR. The micro-structure and the particle-size of the terpolymer particles were studied with the scanning electron microscopy (FE-SEM) and differential light scattering (DLS) method and the results showed that the average... 

In order to prevent a blow out, cooling the bit, displacement of drilling particle, etc., it is necessary to use a suitable fluid called drilling mud. The construction of drilling mud, especially the oil base, has a high cost and covers more than 20% of drilling costs, so maintaining and proper use of it is important, as well as drilling the reservoir layer due to the higher permeability of this layer than Other layers allow the drilling mud to influx into the formation, which in addition to the cost of fluid loss, damage to the reservoir, reduce its permeability and many problems during production. Therefore, in order to investigate the phenomenon of fluid loss, measure its size and... 

The reduction of the effective permeability of the reservoir rock in the production area due to various factors is called formation damage. Formation damage is always one of the topics discussed in petroleum engineering. Among the primary and important cases that lead to damage to the formation are the filtration of drilling mud into the production area and the deposition of colloidal particles inside the porous rock during the drilling operation. The length of the productive zone in contact with the drilling fluid usually reaches several hundred feet in Iranian formations. In this study, the aim is to more accurately estimate the amount of permeability reduction caused by the penetration of... 

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... 

Currently, one of the most important problems in the field of drilling is the issue of drilling fluid loss in different formations. The problem of mud loss has been evident since the beginning of oil and gas well drilling operations, so that oil companies spend millions of dollars annually to solve the problem of mud loss. Problems such as pipe jamming, loss of rig production time, well blowout, loss of a large volume of drilling mud and damage to reservoir formations due to loss of drilling fluid are caused. Regarding the drilling variables, many factors cause the decrease or increase of the loss, the most important of which are the weight on the drill bit, drilling speed, the rate of... 

Numerous environmental and industrial applications entail the movement of water and dissolved components like contaminants within aggregated porous media that are characterized by structural, fractured, or macropores in porous media. Over the last few decades, different macroscopic models based on processes have been employed to replicate the transport of contaminants in such environments. A considerable number of these models focus on simulating advective-dispersive transport across relatively extensive inter-aggregate pore domains, with the understanding that interactions within smaller intra-aggregate pores are governed by diffusion. The transfer of nanoparticles between the two domains...