Drift-Flux Modeling of Two-Phase Flow in Wellbores

Abstract

Summary Drift-flux modeling techniques are commonly used to represent two and three-phase flow in pipes and wellbores. Unlike mechanistic models, drift-flux models are continuous, differentiable and relatively fast to compute, so they are well suited for use in wellbore flow models within reservoir simulators. Drift-flux models require a number of empirical parameters. Most of the parameters used in current simulators were determined from experiments in small diameter (2 inch or less) pipes. These parameters may not be directly applicable to flow in wellbores or surface facilities, however, as the flow mechanisms in small pipes can differ qualitatively from those in large pipes. In order to evaluate and extend current drift flux models, an extensive experimental program was initiated. The experiments entailed measurement of water-gas, oil-water and oil-water-gas flows in a 15 cm diameter, 11 m long plexiglass pipe at 8deviations ranging from vertical to slightly downward. In this paper, these experimental data are used to determine drift-flux parameters for steady state two-phase flows of water-gas and oil-water in large-diameter pipes atinclinations ranging from vertical to near-horizontal. The parameters are determined using an optimization technique that minimizes the difference between experimental and model predictions for holdup. It is shown that the optimized parameters provide considerably better agreement with the experimental data than do the existing default parameters. Introduction Multiphase flow effects in wellbores and pipes can have a strong impact on the performance of reservoirs and surface facilities. In the case of horizontal or multilateral wells, for example, pressure losses in the well can lead to a loss of production at the toe or over production at the heel. In order to model and thereby optimize the performance of wells or reservoirs coupled to surface facilities, accurate multiphase pipeflow models must be incorporated into reservoir simulators. Within the context of petroleum engineering, the three types of pipeflow models most commonly used are empirical correlations, homogeneous models and mechanistic models. Empirical correlations are based on the curve fitting of experimental data and their applicability is generally limited to the range of variables explored in the experiments. These correlations can be either specific for each flow pattern or can be flow pattern independent. Homogeneous models assume that the fluid properties can be represented by mixture properties and single-phase flow techniques can be applied to the mixture.

Dynamic Behavior of CO2 in a Wellbore and Storage Formation: Wellbore-Coupled and Salt-Precipitation Processes during Geologic CO2 Sequestration

“…Therefore, while CO 2 migrates through the wellbore, variations in both potential and kinetic energies interactively change the energy state of CO 2 within the wellbore. Additionally, fluid velocities within the wellbore are determined by the mixture velocity ( ) and the drift velocity ( ), which is calculated from the Drift-Flux-Model (DFM) [57]. Specifically, is calculated by solving following momentum equation [55]:…”

Characteristics of water holdup for oil and water mixture flows in horizontal, vertical, and inclined pipes

“…[1,14,15,16] Flores [1] investigated an oil and water flow in inclined and vertical pipes, and proposed a new relationship to caculate the water holdup based on the driftflux model. Hasan and Kabir [14] analyzed the holdup behaviours of oil and water in a deviated system with the assistance of the drift-flux model.…”

“…Interestingly, the results obtained in an oil and water flow are similar to those reported in a gas and liquid flow. [29] Based on the above findings and existing research results, [14,16] the trigonometric functions are adopted to analyze the data packet in Mathematica software. The relationship between the drift velocity and inclination angle can be re-extracted from the experimental data in upward inclined flows as follows:…”

“…[16] In a downward flow, a simple extension of Equation (4) is introduced since a negative drift velocity could be expected as follows:…”

A backward automatic differentiation framework for reservoir simulation

“…The constants are merged before calculation. Case 5 Gas drift velocity for liquid + gas flow in the MSWell model [24] …”