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Gas mobility control is highly required to obtain a sufficiently-expanded and uniformly-developed steam chamber, which is conducive to steam-assisted gravity drainage (SAGD) production. Adding chem...

Hydrate formation and blockage in gas-dominated pipelines has always been an important issue in research of pipeline flow assurance. In this work, a novel hydrate deposition prediction model consid...

Condensate liquids retrograde below the dew point pressure and diminish gas relative permeability and thus reduce the deliverability of gas condensate wells. The deliverability varies due to the changes of gas effective permeability and other parameters; however, the present deliverability testing methods were not applicable to gas condensate wells because those methods were all based on the assumption that the formation properties such as permeability and fluid properties were constant. A new testing method for gas condensate wells is proposed in this work, by which the variable coefficient deliverability equation can be obtained. Case study shows that the variable coefficient deliverability equation obtained from the proposed deliverability testing method can represent changes of formation properties and fluid properties, thus the deliverability of gas condensate wells can be accurately evaluated and predicted by this testing method.

Gas-assisted gravity drainage (GAGD), solving the problem of low volume sweep coefficient for continuous gas injection (CGI) or water-alternating-gas injection (WAG) and increasing the ultimate recovery to a great extent, is a latest method for enhancing oil recovery. However, no effective predicting methods of oil recovery for GAGD exists. The oil recovery is determined by a set of parameters, such as heterogeneity of the formation, wettability, oil and gas density, oil and gas viscosity, viscous force, capillary force, gravity, gas injection rate, and other controllable parameters. Based on the research of producing mechanism of GAGD and dimensional analysis method, the authors analyzed four dimensionless varies, capillary number, bond number, gravity number, and gravity drainage number, and evaluated its influence on oil recovery. Considering the effect of wettability, viscosity ratio, and the difference between oil density and gas density, gravity number and gravity drainage number are modified. Relat...

In abnormal pressure gas reservoirs, a traditional binomial deliverability equation is insufficient to accurately describe the gas filtration theory, but only the trinomial deliverability equation considering non-Darcy flow effect and ripple effect can be reasonable to some extent. When gas reservoirs are characterized by low porosity and permeability, strong heterogeneity, and high water saturation, gas flow, similar to liquid flow, is featured in significant threshold pressure gradient effect. Therefore, a threshold pressure gradient is added to the trinomial deliverability equation, and it is derived that the pressure drop caused by the pressure gradient is a variable related to production but not a constant. Consequently, a novel deliverability equation of abnormal pressure gas reservoirs considering variable threshold pressure drop has been established, providing theoretical guidance for determining reasonable gas production in abnormal pressure gas reservoirs.

Reservoir pressure of condensate gas reservoir is an indispensable parameter for calculation of gas reserves, gas well productivity evaluation, dynamic analysis, and evaluation of anticondensate. The water-drive condensate gas reservoir is ranked among the most complex types during development. In the development process, reservoir pressure declines, condensate oil dropouts, and content of water vapor in condensate gas increases, while edge water invades continuously, thus accurate calculation and prediction of reservoir pressure is particularly difficult and important. Calculation of retrograde gas condensate influenced by porous media adsorption and capillary pressure, and water vapor content in condensate gas tested under different pressure, according to material balance principle, material balance equation of water-drive condensate gas reservoir is established by consideration of absorption in porous media, capillary pressure and water vapor as well, and finally reservoir pressure at any time during p...

During the development of gas condensate reservoirs, condensate oil is separated as reservoir pressure drops to the dew point pressure. The prediction for water breakthrough time, the impact of precipitation of condensate oil, is usually ignored, which results in significant difference between prediction and realistic results. In order to better develop edge water condensate gas reservoirs and accurately predict the water breakthrough time, impact from condensate oil should be considered. Therefore, a new prediction formula of water breakthrough time is derived based on fluid flow in porous media considering impact of anti-condensate. A case study demonstrates that it is necessary to consider impact of condensate oil when predicting water breakthrough time. The new predicting formula provides theoretical basis for further research on edge water displacement mechanism as well as significant guidance for management of edge water gas condensate reservoirs.

The deliverability of gas condensate well can be calculated by using the modified deliverability equation of dry gas well and the pseudopressure deliverability equation. The modified deliverability equation of dry gas well, without considering the effect of condensate accumulation on the gas flow, results in a relatively large error; the practical application of the pseudopressure deliverability equation is not widespread because of the complex in calculating process of the pseudopressure function. The gas relative permeability and pressure is correlated based on the statistics of gas condensate wells, and an accurate and convenient deliverability equation of gas condensate well is derived. The results of case studies verify that the deliverability equation of gas condensate wells proposed is more appropriate to predict the production of the gas condensate wells.

The critical condensate saturation is a key parameter to reflect condensate flow capacity. The authors propose an experimental method to determine the critical condensate saturation and analyze the flow characteristics of gas condensate by coreflooding and chromatography. Using this method, they perform two sets of experiments with real-core of a gas condensate reservoir and a binary mixture fluid of methane and n-pentane under 84°C. Experimental results show that the critical condensate saturation is 3.04% and 4.66% when irreducible water saturation is 40% and 27%, respectively. The results also indicate porous media will raise the dew point pressure. The irreducible water and capillary number effect is conducive to the flow of condensate. Based on experimental researches, the authors theoretically analyze the distribution and mobilization characteristics of condensate. Although critical condensate saturation is low, it doesn't mean the condensate will be able to flow freely when it achieves the value, a...