Papers by Keyword: Water Injection

Abstract: Recently humidified gas turbine systems in which water or steam is injected have attracted much attention, since they can offer a high efficiency and a high specific power with a relatively low cost compared to combined-cycle gas turbine systems, and therefore they have a potential for future power generation. In this study, performance analysis of the wet compression process is carried out with an analytical modeling which was developed from heat and mass transfer, and thermodynamic analyses based on droplet evaporation. Wet compression variables such as temperature-averaged polytropic coefficient, compressor outlet temperature, and compression work are estimated. Parametric studies show the effect of system parameters such as droplet size, water injection ratio or compression ratio on transient behavior.

Abstract: In wet compression process water is injected at an inlet of compressor and continuous cooling occurs due to evaporation of water droplets during the compression process of air, which can save the compression work and enhance the performance of gas turbine system. In this work, performance analysis of the wet compression process is carried out under the critical conditions of water injection which are defined as the maximum water injection which can be evaporated completely inside the compressor. For various ambient conditions the important variables of wet compression process such as water injection ratio, temperature-averaged polytropic coefficient, compressor outlet temperature, and compression work are estimated under the critical injection conditions. Parametric studies show that compression work decreases with ambient temperature, however, the reduction ratio of compression work relative to dry increases with ambient temperature.

Abstract: When water is injected at an inlet of compressor, wet compression occurs due to evaporation of water droplets. In this work, the effects of wet compression on the performance of regenerative gas turbine cycle with turbine blade cooling are analytically investigated. For various pressure ratios and water injection ratios, the important system variables such as ratio of coolant flow for turbine blade cooling, fuel consumption, specific power and thermal efficiency are estimated. Parametric studies show that wet compression leads to significant enhancement in both specific power and thermal efficiency in gas turbine systems with turbine blade cooling.

Abstract: The aim of this work is to study theoretically the effect of porosity of an oil reservoir with arbitrary geometry on the oil recovery factor. A two-dimensional mathematical modeling (Black-oil model) and numerical solution applied to two-phase flow (water-oil) into the reservoir with irregular geometry including water injection is presented. The conservation equations written in generalized coordinates are solved using the finite volume method, with a fully implicit technique. Results of the pressure and saturation distributions and oil recovery factor over time are presented and evaluated for different values of porosity of the reservoir.

Abstract: The water and steam injection gas-turbine systems are comparatively investigated. Thermodynamic performances of the regenerative after-fogging gas-turbine (RAF) system, steam-injection gas-turbine (STIG) system, and the regenerative steam-injection gas-turbine (RSTIG) system are analyzed parametrically. Using the analytic model, the important system variables such as thermal efficiency, fuel consumption, specific power, and specific emission of CO2 gas are evaluated in terms of pressure ratio and water or steam injection ratio. The numerical results show that water or steam injection results in a notable enhancement of thermal efficiency and specific power.

Abstract: Well casing damage is a commonly existing problem in oilfield exploitation in the world. Daqing oilfield is a multiple-zone, heterogeneity sandstone oilfield, where the major influence factors which lead to casing damage are geologic factor, engineering factor, high pressure water injection and chemical factors. Among them, the high pressure water injection is the most important one. Water injection exploitation in Daqing oilfield showed that casing-damage increased with the increasing water injection pressure. However, the mechanism is not totally understood and the control method is not well developed yet. In the present work, the mechanism analysis of casing damage induced by high pressure water injection in Daqing oilfield is proposed. It is found that after high pressure water injection, the sandstone layer will expand and result in the vertical elongation of the casing. The additive tensile stress of the casing induced by vertical strains will cause casing-damage. Besides, the horizontal deformation of clay-stone increases with increasing water content of the formation layers and soaking time. The cohesion of clay-stone and inner friction angle decreased with increasing water quantity. In that case, some high obliquity formation layers which may induce high hypsography pressure difference will cause localized slip along weak formation layer interface in the area of waterishlogged clay-stone. Casing damage and well failure caused by the relative movement of the formation layer interface may therefore occur. The micro-fracture of formation induced by high pressure water injection also educed formation rupture and casing damage.

Abstract: This paper compares the pressure drop profiles of both horizontal well producer and injector in a 5spot waterflood pattern. Dimensionless pressure distributions for each pattern were utilised. All computations were limited to conditions of unit mobility ratio; i.e., before water breakthrough condition. Results show that a normal 5-spot flood pattern, with a horizontal well producer, offers higher pressure drops, but early water breakthrough tendencies, than as an injector for the same reservoir and wellbore conditions. An inverted pattern, under the same conditions, produces clean oil for a longer time, before water breakthrough possibilities.