Sharif Digital Repository

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... 

Clogging of the pores of the porous medium occurs in different processes such as geothermal injection pumps, hydrocarbon wells, and underground water extraction wells. We need a model that can simulate these blockages in order to predict how fundamental variables of the porous medium change under different flow regimes and different particle sizes in the fluid (for example, the relationship between porosity and permeability changes). The aim is to simulate clogging in a porous medium using a pore network model. Simulations should model pore clogging and show how the permeability of the sample changes due to pore clogging. In the pore network, there are often thousands (or millions) of pores... 

Geotextiles are one of the most widely used materials in filtration and drainage applications. Since geotextiles are exposed to different stresses and hydraulic gradients, thier hydraulic behavior in real situations is of great importance. In this study, filtration and drainage of several nonwoven needle-punched geotextiles with different properties and unit masses per area of 200g/m2, 400g/m2, 500g/m2 and 800g/m2 under various confined stresses and hydraulic gradients are investigated. To get to these aims, permittivity and transmissivity apparatuses were designed and built in the course of this investigation. Then samples which were emerged for at least 24 hours were tested under different... 

Given that the mean of the cost of drilling operation related to the required martials and preparation of the drilling fluids, therefore, the design and construction drilling fluid which omit has to be a proper rheology is essential in drilling operations and oil industry. A desirable property of the drilling fluid is the minimum fluid loss volume which can be achieved by formation of a low permeability filter cake on the wellbore. Drilling fluid filtrating invasion into the formation can cause formation damage and reduction in the productivity of the well. In drilling fluids, a series of natural synthetic and polymers may be used as fluid (filtration) loss control additives. However, high... 

Lipases (Triacyl Glycerol Acyl Hydrolase, EC.3.1.1.3) are multidimensional biocatalysts which have many applications in food industrials, dairy, fats and oils processing, detergents, synthesis of pure chemical and pharmaceutical materials, paper industrial and cosmetics. Generally, industrial enzymes are produced extracellularly, so their separation from a low-cost complex medium (usually used for production) is one of the cost stages in their production process. Filtration is the most economical method of separation in the production of enzymes, but due to the small size of colloidal particles and cell masses present in the fermentation environment, its use is subject to limitations. In... 

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... 

The mathematical analysis of the kidney has always been considered due to its complex performance. It’s about two decades that mathematicians work on the mathematical modeling of this tissue. Since Glomerular filtration of blood in the kidney has been regarded by physiologists for many years, they can access only to the qualitative data. Mathematicians can solve this problem by numerical modeling. In this research, an engineering model is presented for the analysis of this capillary network by investigating in the different scientific fields such as, physiology, medicine, computer science and mathematics.First of all, the homogeneous model introduced by Deen, are studied. The rate of the... 

In biotechnology processes, in addition of culture media there is a solid phase which dispensed across the system.In most of bioprocesses, first operational unit for downstream treatment is the separation of this particles from fermentation liquor. In contrast with other categories like inorganic chemistry, solid particles in fermentation liquor (which the main part of it is biomass itself) have complicated physical & rheological properties. For example, all of biomass species are hydrophilic and sometimes form colloidal solutions.With this perspective, separation of solid phase from fermentation liquor is a hard challenge in this kind of processes.In this research, with regard of great...