Viscosity Modeling and Prediction of Reservoir Fluids: From Natural Gas to Heavy Oils

Abstract

Viscosity and density are key properties for the evaluation, simulation, and development of petroleum reservoirs. In previous work, the friction theory (f -theory) models have already been shown capable of providing simple but accurate viscosity modeling results of petroleum reservoir fluids with molar masses up to around 200 g · mol −1 . As a base, the f -theory approach requires a compositional characterization procedure to be used in conjunction with a van der Waals type of equation of state (EOS). This is achieved using simple cubic EOS, which are widely used within the oil industry. In this work, the f -theory approach is further extended to the viscosity modeling of heavy reservoir fluids with viscosities up to thousands of mPa · s. Essential to the extended approach presented here is the achievement of accurate pvT results for the EOS characterized fluid. In particular, it has been found that for accurate viscosity modeling of heavy oils, a compressibility correction in the way the EOS is coupled to the viscosity model is required. With the approach presented in this work, the potential of the f -theory for viscosity modeling of reservoir fluids is extended to practically all kind of reservoir fluids, from light ones to heavy ones. Additionally, the approach has been completed with an accurate density modeling scheme.

General friction theory viscosity model for the PC‐SAFT equation of state

“…This accurate viscosity prediction is achieved using simple mixing rules for the friction coefficients. Further, the general PC‐SAFT f‐theory model can potentially be extended to the viscosity modeling and prediction of crude oils based on the mass characterization procedure already introduced in an f‐theory –related work16—the subject of a forthcoming report. In addition, the general PC‐SAFT f‐theory approach will also be applied to other asymmetric mixtures such as refrigerant + lubricant systems.…”

“…Before proceeding it is illustrative to underline some of the basic motivations for extending the f‐theory to the PC‐SAFT EoS. One of the problems encountered with the application of cubic EoS–based f‐theory models to complex fluids, such as heavy or degraded reservoir fluids, is the compressibility response of such simple models under high pressure 16. This problem may be related to the mathematical and theoretical limitations of the van der Waals repulsive term as it is extended to high‐pressure conditions.…”

“…Further, the f‐theory has been developed into a general model for these EoSs 5, 6. Despite the simplicity of the cubic EoS, it has been shown that the f‐theory approach can provide, in a simple way, accurate viscosity predictions and modeling results over wide ranges of temperature, pressure, and composition for many fluids of industrial importance and complexity, such as CO 2 + hydrocarbons,7 light gases,8 refrigerants,9 lubricants,10 refrigerant + lubricant,11 as well as multicomponent mixtures ranging from natural gas12, 13 to heavy oils14–16 with viscosities ranging between 10 −2 and 10 4 mPa·s (or even higher).…”

A unique approach to predict accurate heavy oil density with new three parameter cubic equation of state

“…BIP values used for density and viscosity modelling using the PR EoS by Quiñones‐Cisneros et al (2004b) were also used in the present work. With the mixing rules presented in Equations (7)–(10), the following binary parameters were used (Quiñones‐Cisneros et al, 2004b): 0.02 for N 2 ‐C1, 0.06 for N 2 ‐(C2‐C3), 0.08 for N 2 ‐C i >3 , 0.12 for CO 2 ‐C1, and 0.15 for CO 2 ‐C i >1 , and finally 0 for all hydrocarbon to hydrocarbon interactions including the pseudo fractions.…”

Modélisation de la viscosité des fluides de gisement : Apport de la PLS bootstrap et des réseaux de neurones

“…Une autre approche des équations d'état a été envisagée par Quinones-Cisneros et al (2001,2004) [19,20] [18]. Combinées à ces équations, des lois de mélange basées sur la composition du fluide et un paramètre d'ajustement permettent la résolution de cette méthode.…”