Commonly-used screening techniques for determination of biosurfactants production by microorganisms include haemolysis assay, generally depicted to confirm the ability of microorganisms in production of biosurfactants. Diameters of zones of haemolysis surrounding microbial colonies are considered as quantitative indication of biosurfactant production whereas; haemolytic reactions on blood agar plates are specifically associated with pathologic types of erythrocyte lysis by microorganisms, due to haemolysins production. Haemolytic microorganisms can destroy erythrocyte membranes, by compromise in integrity of cytoplasmic membranes, through pore-forming mechanisms, multiple-hit mechanism, formation of sphaerocytes, derangement of membrane integrity, detergentlike action, or lipase activity. Relative levels of acute toxicity, cell invasiveness and virulence factors, which can make biosurfactants become opportunistic pathogens that use haemin or haemoglobin as a source of iron, have also been reported. Haemolysins are further classically defined as exotoxins that can be thermostable, and can cross membranes of microorganisms. Haemolysis assay thus, identifies haemolytic microbial strains with lytic, pathogenic, toxigenic, and/or virulent potentials, rather than biosurfactant-producing potential, as the assay does not correlate particularly with specific characteristics of biosurfactants’ production. However, based on new insights and perspectives appropriately extrapolated for the first time in this report, microbial haemolysis assay is considered, the easiest, most-economical, non-animal-based, highly-determinative, reliable and sensitive biosafety selection criterion protocol, for selection of safe and environmental-friendly biosurfactant candidates, for the petroleum industries’ process conditions.
Composting is proved to be environment friendly effective management option for the increasing volume of coffee wastes generated and causing significant environmental degradation in developing countries. In view of this, the quality of composts produced from coffee pulp with locally available organic matter following the windrow method was examined based on four treatments in randomized complete block design (4x3). The study involved determining some physicochemical parameters at 25, 55 and 80 days of composting. Mean values of bulk density, moisture content, pH, electric conductivity, organic matter, total organic carbon, total nitrogen, total phosphorous, total potassium and carbon to nitrogen ratio ranged from 483.6 kg/m –487.11 kg/m3, 50.74%–52.43%, 7.45-8.36, 3.08 mS/cm-3.42 mS/cm, 45.26%-46.99%, 26.19%-27.27%, 1.54%-1.61%, 0.41%-0.59%, 0.75%-1.15% and 17.5-18.44, respectively. Bulk density, total nitrogen, total phosphorous and total potassium increased with composting time in contrast to moisture content, organic matter, total organic carbon and C/N. pH and electrical conductivity initially increased but decreased at final stage. Mean physicochemical parameters of matured composts fell within the range of acceptable limits set by different countries guidelines. All parameters were not significantly different (p>0.05) except moisture content, pH and total potassium as compared to within treatments (p<0.05). The results revealed that a mixture of 50% coffee pulp,20% cow dung, 20% enset leaf and 10% top soil is more preferable to produce quality compost and consequently protect the environment.
Sri Lanka is a tropical island located near to the southeast tip of India. The country lies in the between longitudes 79° 39' 81° 53' East and latitudes 5° 54' 9° 52' North. It consists of 64,453.6 km2 of land area and 1,156.2 km2 of inland waters. Extensive faulting and erosion over time have produced a wide range of topographic features, making Sri Lanka one of the most scenic places in the world (Annual Performance Report of Meteorology Meteorology, 2018).
Kuwait has successfully reached a production rate of three million barrels and is planning to increase the oil production by 4 million barrels on the year 2020. Beside the production rate, Kuwait oil companies are getting ready to extend upstream and downstream areas including building new facilities since the demands are growing more and more and Kuwait has a responsibility for its nation since it is a successful and main country in exporting oil. Therefore, Kuwait must make sure that oil is being produced with the best current technologies and having the best people in production line with enough knowledge and experience with the plans and taking lowest risks to remain in first places of ranking and leading countries in oil production.
Environmental biotechnology specifically is the use of cycles for the insurance and rebuilding of the nature of the climate. Ecological biotechnology can be utilized to recognize, forestall and remediate the outflow of toxins into the climate in various manners.
As the major gas resource of the West-East Gas Transmission Project, Kela 2 gas field plays an important role in the natural gas industry development and social demand in China. After 17 years development, annual gas production of Kela 2 gas field is stable in over 5 billion cubic meters, which has great reference value for the other gas field’s development. Kela 2 gas field is in the middle-late development period at present, some gas wells experienced water flooding in advance, which has resulted in a productivity decrease. Main challenges at current development period are development scheme adjustments such as water invasion prevention, water invasion control, production allocation optimization, and the conventional geological modeling cannot meet the scale requirement for the development scheme adjustment. By using the fine scale geological modeling techniques, it could provide a basis for the study of remaining reserves distribution, horizontal well deployment, water control and drainage scheme design.
The present investigation deals with the impact of crude selection on Kerosine, Aviation Turbine Fuel, Gasoline and Diesel product specification. To carry out this, four different crude oils are selected on random basis from four different regions namely Middle East, North America, West Africa and Europe. Based on the product specifications given by Indian Standard, how the properties of kerosine cut, naphtha cut and diesel cut from crude oil assay are affecting the product specifications and operating costs of a petroleum refinery is elaborated.
Conventional artificial lift systems are limited in their application by depth, borehole trajectory, and the produced media's chemistry. This publication presents a performance analysis of the concentric tubular pumping system, which combines the practical concentric tubular completion with the efficient reciprocating hydraulic piston pump to overcome the limitations of existing artificial lift systems cost-effective production for unloading of gas wells and heavy oil recovery. This pumping system consists of a specially designed plunger assembly and barrel combination driven by a hydraulic pressure unit from the surface without any mechanical connection. The hydraulic pump can be circulated into and out of the borehole or run by slick line, resulting in fast and low-cost installation. The pump is designed to run as a concentric tubular pumping system. This paper introduces the pump’s concept, the fluid dynamics simulation, and pump testing at the pump test facility to prove its working principle. The simulations and lab tests have demonstrated very high system efficiencies. The lab tests confirmed the simulation results. At the defined pressure boundary conditions and a speed of 1.5 SPM, a production rate of 9.4 m³/day at a lift efficiency of 95.4 percent was achieved. At 7.6 SPM, the production rate is 100 m³/day, but the system efficiency dropped to 0.25. This pump's unique design requires a low number of moving parts, such as no mechanical connection to the surface and providing minimal exposure to wear and corrosion. Tests have shown that the pump is very adaptable regarding production rate, which requires a change in surface hydraulic pressure, which is typically in a range between 30 and 80 bars. Based on experience, the concentric tubular pumping system is the best selection for unloading gas wells to enhance the completions' lifetime. In This utterly new pump type exceeds the performance of existing artificial lift systems, increases the mean time between failures, and essentially reduces lifting costs.
Collapse of casings during production has been reported on many occasions in different fields. Regardless of the root for the failure of the casings, this is due to stresses applied to the casing exceeding its ultimate strength. Failure of the casing similar to any pipe could be due to compressional, tensional, and burst or collapse forces due to various loads being applied to the casing string. Although several analytical models have been developed based on elastic or plastic approaches to estimate the ultimate strength of casing, it has been shown that these methods underestimate the casing strength. Casings’ mechanical and geometrical parameters, effective in-situ stresses, temperature, formation properties and other intervening are simultaneously required for a complete design of casing. To simulate the failure of casing in the presence of various forces, numerical modeling is a robust approach that can be employed. In this study, finite element simulation was used through the use of ABAQUS software to model the failure of casings in one of the wells located in the southern part of Iran. The results revealed that increasing the diameter to thickness (D/t) ratio decreases the ultimate strength of casing, leading to unexpected failure in the wells under consideration. It was also shown that eccentricity drastically reduces the strength of casing. Since the numerical results of current study were in an acceptable agreement with experimental studies, numerical simulation method proposed here can be used to predict the casing collapse. Casing is a set of several steel pipes joined together and used to protect the wellbore after it is drilled. The casing is subjected to various loads in short term during drilling and long terms during production. Buckling due to axial load and burst and collapse as a result of high internal and external pressures, respectively, are examples of excessive loads and subsequent casing failure mechanisms. Casing damage is perhaps one of the most frequently reported failures in oil and gas drilled wells. This may happen during reservoir depletion due to excessive load caused by buckling or change in temperature gradient. Casing failures induced by formation compaction have also been observed in various reservoirs located at the North Sea, the US Gulf of Mexico, California, South America and Asia. These examples demonstrate that casing must be designed appropriately in order to resist excessive external forces during its intended life. A casing with lower diameter to thickness ratio (D/t) and higher material strength will be more resistance to applied forces. However, optimum sizes should be chosen for economical purposes. To determine the proper casing specifications the worst loading condition that the casing may experience during its life should be identified. During installation, casing experiences a combination of pressure, bending and axial loads, but when it reaches to its predetermined location it would be under external pressure only. Practically, the hydrostatic pressure applied to the outside surface of casing inside the annulus space during drilling phase before cementing is perhaps the most important load to be considered for the design of casings. Practical methods initially used for prediction of casing collapse were principally based on the empirical solutions. These equations have been developed to establish a linear or nonlinear relationship between collapse pressure and important parameters causing a casing to collapse. From the reported literature the ratio of outside diameter to wall thickness (D/t), initial ovality and eccentricity are the most important geometrical parameters of the casing to be considered for design purposes. The important mechanical properties include the Young's modulus, Poisson's ratio and the yield strength of casing. Residual stress and applied axial stress are also needed to be considered. However, it is important to realize that casing collapse occurs under plastic regime, as a result of which yield stress based on Von-Mises failure criterion has been embedded into the empirical equations. Further investigations have suggested that considering the yield stress through the Von-Mises criterion underestimates the collapse strength. Therefore, several equations were proposed later to predict the collapse of casing including both elastic and plastic behavior of the pipe. The casing in that study was assumed to have an elastic–plastic behavior and showed to be accurate when it was used for collapse prediction of metal pipes. The analytical equations proposed for estimation of collapse strength are limited to the assumptions used in their development and are reliable for specific type of materials. Numerical simulations may be used alternatively for such analysis. In this study, an elastic-plastic FEM model was used to analysis the collapse strength of casing in one well located in South part of Iran.
