Thermodynamic Analysis of Phase Behavior at High Capillary Pressure

Summary High capillary pressure has a significant effect on the phase behavior of fluid mixtures. The capillary pressure is high in unconventional reservoirs because of the small pores in the rock, so understanding the effect of capillary pressure on phase behavior is necessary for reliable modeling of unconventional shale-gas and tight-oil reservoirs. As the main finding of this paper, first we show that the tangent-plane-distance method cannot be used to determine phase stability and present a rigorous thermodynamic analysis of the problem of phase stability with capillary pressure. Second, we demonstrate that there is a maximum capillary pressure (Pcmax) where calculation of capillary equilibrium using bulk-phase thermodynamics is possible and derive the necessary equations to obtain this maximum capillary pressure. We also briefly discuss the implementation of the capillary equilibrium in a general-purpose compositional reservoir simulator. Two simulation case studies for synthetic gas condensate reservoirs were performed to illustrate the influence of capillary pressure on production behavior for the fluids studied.

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A Rigorous Solution to the Problem of Phase Behavior in Unconventional Formations With High Capillary Pressure

SPE Journal ◽

10.2118/187260-pa ◽

2018 ◽

Vol 23 (04) ◽

pp. 1438-1451 ◽

Cited By ~ 5

Author(s):

Sajjad S. Neshat ◽

Ryosuke Okuno ◽

Gary A. Pope

Keyword(s):

Phase Behavior ◽

Capillary Pressure ◽

Gas Oil ◽

Rigorous Solution ◽

Shale Formations ◽

New Approach ◽

Three Phase ◽

Capillary Equilibrium ◽

Stability Method ◽

New Criterion

Summary Phase behavior of hydrocarbon mixtures is affected by the petrophysical properties of the formation. This paper integrates several important thermodynamic and petrophysical aspects of the problem in a rigorous way and introduces a solution that can be applied over the range of pore sizes in tight and shale formations in which hydrocarbons can be practically recovered. A new criterion for phase-stability analysis is introduced that results in discovery of a new range of solutions for the capillary equilibrium problem. A novel three-phase capillary pressure model has been used to estimate the effect of connate water on the gas/oil capillary pressure. The model is then used in conjunction with the new stability method to solve several phase-behavior problems for binary and multicomponent reservoir fluids. We show that the new approach can significantly improve the estimation of phase behavior at high capillary pressure.

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Study on Phase Behavior of CO2/Hydrocarbons in Shale Reservoirs Considering Sieving Effect and Capillary Pressure

Natural Resources Research ◽

10.1007/s11053-021-09886-6 ◽

2021 ◽

Author(s):

Yapeng Tian ◽

Binshan Ju ◽

Xudong Wang ◽

Hongya Wang ◽

Jie Hu ◽

...

Keyword(s):

Phase Behavior ◽

Capillary Pressure ◽

Shale Reservoirs ◽

Sieving Effect

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A General Purpose Single-Phase Naturally Fractured (Carbonate) Reservoir Simulator With Rigorous Treatment of Rock-Stress/Fluid-Pressure Interactions and Interporosity Flow

10.2118/13528-ms ◽

1985 ◽

Cited By ~ 2

Author(s):

W.F. Leung

Keyword(s):

Single Phase ◽

Fluid Pressure ◽

General Purpose ◽

Carbonate Reservoir ◽

Rock Stress ◽

Naturally Fractured ◽

Fractured Carbonate ◽

Rigorous Treatment ◽

Reservoir Simulator

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Thermodynamic Analysis of Relaxation Model for Non-Equilibrium Phase Behavior of Hydrocarbon Mixtures

Journal of Physics Conference Series ◽

10.1088/1742-6596/2090/1/012138 ◽

2021 ◽

Vol 2090 (1) ◽

pp. 012138

Author(s):

I M Indrupskiy ◽

P A Chageeva

Keyword(s):

Relaxation Time ◽

Phase Behavior ◽

Relaxation Process ◽

Thermodynamic Analysis ◽

Balance Equation ◽

Equilibrium Phase ◽

Characteristic Relaxation Time ◽

Relaxation Model ◽

Entropy Balance ◽

Non Equilibrium

Abstract Mathematical models of phase behavior are widely used to describe multiphase oil and gas-condensate systems during hydrocarbon recovery from natural petroleum reservoirs. Previously a non-equilibrium phase behavior model was proposed as an extension over generally adopted equilibrium models. It is based on relaxation of component chemical potentials difference between phases and provides accurate calculations in some typical situations when non-instantaneous changing of phase fractions and compositions in response to variations of pressure or total composition is to be considered. In this paper we present a thermodynamic analysis of the relaxation model. General equations of non-equilibrium thermodynamics for multiphase flows in porous media are considered, and reduced entropy balance equation for the relaxation process is obtained. Isotropic relaxation process is simulated for a real multicomponent hydrocarbon system with different values of characteristic relaxation time using the non-equilibrium model implemented in the PVT Designer module of the RFD tNavigator simulation software. The results are processed with a special algorithm implemented in Matlab to calculate graphs of the total entropy time derivative and its constituents in the entropy balance equation. It is shown that the constituents have different signs, and the greatest influence on the entropy is associated with the interphase flow of the major component of the mixture and the change of the total system volume in the isotropic process. The characteristic relaxation time affects the rate at which the entropy is approaching its maximum value.

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Thermodynamic analysis of copper(I) sulfide chlorination by calcium chloride in the presence of oxygen

Journal of the Serbian Chemical Society ◽

10.2298/jsc9906365v ◽

1999 ◽

Vol 64 (5-6) ◽

pp. 365-374 ◽

Cited By ~ 1

Author(s):

Rajko Vracar ◽

Katarina Cerovic

Keyword(s):

Calcium Chloride ◽

Thermodynamic Analysis ◽

Chemical Reactions ◽

Phase Stability ◽

Log P ◽

Temperature Range ◽

Stability Diagrams

This paper presents a thermodynamic analysis of possible, but insufficiently studied, chemical reactions occurring during the chlorination of copper(I) sulfide by calcium chloride in the presence of oxygen. It formed the basis for assessing the probability and priority of their occurrence. Phase stability diagrams have been plotted for the Cu-S-O-Cl system in the coordinates log p(S2)-log p(O2)-log p(Cl2) in the temperature range from 473 to 773 K.

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