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This paper investigates some fundamental aspects of a "vaporiser" for recovering trapped retrograde condensate in the formation that is formed during exploitation gascondensate reservoirs in depletion regime. The thermodynamic test of seven different gas-condensate systems and analysis of the liquid and gas phase's samples which were taken under the same thermobaric conditions was provided wide information about the occurrences in the reservoir fluids. It was identified that the solubility capability of gas mixture in the hydrocarbon condensate is elevated and improved as a "vaporiser" if it's critical temperature is increased but compressibility factor and critical pressure are decreased. It was determined that, improving the solubility of gas components in the condensate decreases the system fog up and retrograde condensation pressures and improves stability of aerosol condition of gas-condensate fluid. Therefore, injected gas for gas cycling or re-vaporization of condensate from the core can be controlled for the purpose of increasing its solubility.Keywords: gas-condensate, gas injection, fog up pressure, gas solubility, gas solubility, dissolved gas vaporization of heavy hydrocarbon ends and connate water, the reduction of the condensate/gas ratio and RDP pressure, etc. 12,15 Nevertheless, successful design and implementation of enhanced condensate recovery schemes require accurate prediction of the compositional effects that control the local vaporization/displacement efficiency. In line with these conclusions, and also results which were obtained in the earlier works 4,14,15 in this paper, we intended to find out a way of improving the effectiveness of "vaporiser" for the recovering trapped retrograde condensate in the formation, which is left after primary production. To this purpose, this paper performed an experimental investigation into this phenomenon as it is problematic during mathematical modelling. Investigation method and procedure Laboratory apparatusesExperiments were carried out on a УГК type of PVT bomb, which is a standard apparatus for determining thermodynamic characteristics and the phase behaviour of gas condensate systems. 1 The schematic diagram of the experimental laboratory apparatus and the purposes of the laboratory modules are presented in the Figure 1. The maximum working pressure of the PVT bomb is 45MPa, maximum working temperature is 80°C and cell volume is 3x10 -3 m 3 . As shown in the diagram Figure 1, the laboratory facility can be divided into 9 Modules: Figure 1 Schematic representation of laboratory apparatusModule 1: Module 1 is for handling natural gas from the bottle. It is equipped with Natural Gas Bottle-NGB, CO 2 Bottle-CB, Nitrogen Bottle-NB, Pressure Control Valve-PCV, Flow Meter-FM and normal Isolation Valve-IV. Sample Connection-SC allows the provision of sampling for composition analyses. This module can be linked very easily with Modules 3 and 5 by manifold (Module 9) for recombining gas mixture and gas-condensate system. Module 2:Module 2 is for han...

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In this paper, considering gas-condensate mixture researched as dispersed system, the effect of grouped components, fractural compositions and liquid-gas ratio on the fluid dispersion and condensation processes were shown in line with importance of these factors at development and exploitation of gas condensate deposits. The analysis of some thermodynamic data from different deposits revealed that if the liquid part of the gas-condensate system consists of relatively light components or mixture is composed of the better soluble liquid and gas components, then the dispersion can be processed in low pressure condition at a certain temperature. In this case, stability of the dispersed reservoir fluid and its single-phase state could prolong longer during depletion regime. Besides, it was found out that the condensate recovery factor is low when the condensate ratio of the reservoir is relatively high. This is due to the increase of proportion between liquid and gas volumes causing poor dispersion process of volume liquid phase in dispersed medium. The results were proved by experimental studies and also, some of the application problems of depletion process were investigated.

The conventional equations for describing the flow characteristics of the mixtures merely consider fluid that is homogenic, if it is above the bubble point conditions but ignore that a system containing sub-micron sized gas or vapor bubbles distributed throughout the volume of the liquid, which can exhibit unexpected heterogenic and complex phase properties. In this paper, a new mathematical model for the flowing gas-liquid mixture is presented, which has been proposed considering the colloidal feature of the system above the saturation or bubble point pressure. This approach is more in line with the actual dynamic performance of the oil and gas mixture export pipeline. Experimental data, simulations and field case studies validate the new proposed mathematical model of flow characteristics in pipeline. The obtained results confirmed that the calculated data are in good agreement with the experimental data. Based on Azerbaijan oil-gas-condensate field “Guneshli” data, this new model was used for calculating the condition in which the transformation of the flow characteristics from stable into instable is occurred. It has been discovered that the flow becomes unstable at a pressure about 30% higher than Bubble Point Pressure, which causes pulsation effect in the pipeline structure. However, homogenic behavior should be observed in this hydrodynamic condition. Also, the model provides a guideline on how to optimize the flow rate by adjusting the pipeline parameters to minimize the flow resistance, liquid slugging and hydraulic hammering effects, which cause instable operation.

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