The effect of surfactants on air–water annular and churn flow in vertical pipes. Part 2: Liquid holdup and pressure gradient dynamics

2015 ◽  
Vol 71 ◽  
pp. 146-158 ◽  
Author(s):  
A.T. van Nimwegen ◽  
L.M. Portela ◽  
R.A.W.M. Henkes
Keyword(s):  
Pressure Gradient ◽  
Liquid Holdup ◽  
Gradient Dynamics ◽  
Churn Flow

Experimental Study of DRA for Vertical Two-Phase Annular Flow

2009 ◽  
Vol 131 (2) ◽  
Author(s):  
R. L. J. Fernandes ◽  
B. A. Fleck ◽  
T. R. Heidrick ◽  
L. Torres ◽  
M. G. Rodriguez
Keyword(s):  
Pressure Gradient ◽  
Drag Reduction ◽  
Production Rate ◽  
Annular Flow ◽  
Liquid Holdup ◽  
Two Phase ◽  
High Production Rate ◽  
High Production ◽  
Feasibility Test ◽  
Main Effects

Experimental investigation of drag reduction in vertical two-phase annular flow is presented. The work is a feasibility test for applying drag reducing additives (DRAs) in high production-rate gas-condensate wells where friction in the production tubing limits the production rate. The DRAs are intended to reduce the overall pressure gradient and thereby increase the production rate. Since such wells typically operate in the annular-entrained flow regime, the gas and liquid velocities were chosen such that the experiments were in a vertical two-phase annular flow. The drag reducers had two main effects on the flow. As expected, they reduced the frictional component of the pressure gradient by up to 74%. However, they also resulted in a significant increase in the liquid holdup by up to 27%. This phenomenon is identified as “DRA-induced flooding.” Since the flow was vertical, the increase in the liquid holdup increased the hydrostatic component of the pressure gradient by up to 25%, offsetting some of reduction in the frictional component of the pressure gradient. The DRA-induced flooding was most pronounced at the lowest gas velocities. However, the results show that in the annular flow the net effect will generally be a reduction in the overall pressure gradient by up to 82%. The findings here help to establish an envelope of operations for the application of multiphase drag reduction in vertical flows and indicate the conditions where a significant net reduction of the pressure gradient may be expected.

scholarly journals Frictional Pressure Drop and Liquid Holdup of Churn Flow in Vertical Pipes with Different Viscosities

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Zilong Liu ◽  
Yubin Su ◽  
Ming Lu ◽  
Zilong Zheng ◽  
Ruiquan Liao
Keyword(s):  
Pressure Drop ◽  
Liquid Velocity ◽  
Gas Velocity ◽  
Liquid Holdup ◽  
Two Phase ◽  
Frictional Pressure Drop ◽  
Viscous Oil ◽  
Predicted Values ◽  
Superficial Gas Velocity ◽  
Churn Flow

Churn flow commonly exists in the pipe of heavy oil, and the characteristics of churn flow should be widely understood. In this paper, we carried out air and viscous oil two-phase flow experiments, and the diameter of the test section is 60 mm. The viscosity range of the oil was 100~480 mPa·s. Based on the measured liquid holdup and pressure drop data of churn flow, it can be concluded that, due to the existence of liquid film backflow, positive and negative frictional pressure drop can be found and the change of frictional pressure drop with the superficial gas velocity is related to superficial liquid velocity. With the increase of viscosity, the change rate of frictional pressure drop increases with the increase of the superficial gas velocity. Combining our previous work and the Taitel model, we proposed a new pressure drop model for viscous oil-air two-phase churn flow in vertical pipes. By comparing the predicted values of existing models with the measured pressure drop data, the proposed model has better performance in predicting the pressure drop.

The Effect of Surfactants on Vertical Air/Water Flow for Prevention of Liquid Loading

SPE Journal ◽  
2016 ◽  
Vol 21 (02) ◽  
pp. 488-500 ◽  
Author(s):  
A. T. van Nimwegen ◽  
L. M. Portela ◽  
R. A. Henkes
Keyword(s):  
Surface Tension ◽  
Pressure Gradient ◽  
Water Flow ◽  
Annular Flow ◽  
Surfactant Concentration ◽  
Gas Flow ◽  
Liquid Loading ◽  
Dynamic Surface ◽  
Flow Rates ◽  
Churn Flow

Summary From field experience in the gas industry, it is known that injecting surfactants at the bottom of a gas well can prevent liquid loading. To better understand how the selection of the surfactant influences the deliquification performance, laboratory experiments of air/water flow at atmospheric conditions were performed, in which two different surfactants (a pure surfactant, sodium dodecyl sulfate, and a commercial surfactant blend) were added to the water. In the experiments, a high-speed camera was used to visualize the flow, and pressure-gradient measurements were performed. Both surfactants increase the pressure gradient at high gas-flow rates and decrease the pressure gradient at low gas-flow rates. The minimum in the pressure gradient moves to lower gas-flow rates with increasing surfactant concentration. This is related to the transition between annular flow and churn flow, which is shifted to lower gas-flow rates because of the formation of an almost stagnant foam substrate at the wall of the pipe. At high surfactant concentration, it appears that the churn flow regime is no longer present at all and that there is a direct transition from annular flow to slug flow. The results also show that the critical micelle concentration, the equilibrium surface tension, the dynamic surface tension, and the surface elasticity are poor predictors of the effect of the surfactant on the flow.

Experimental and Modeling Studies on Pressure Gradient Prediction for Horizontal Gas Wells Based on Dimensionless Number Analysis

2021 ◽  
Author(s):  
Chengcheng Luo ◽  
Ning Wu ◽  
Sha Dong ◽  
Yonghui Liu ◽  
Changqing Ye ◽  
...  
Keyword(s):  
Experimental Investigation ◽  
Pressure Gradient ◽  
Flow Behavior ◽  
Scaling Up ◽  
Low Pressure ◽  
Dimensionless Number ◽  
Gas Wells ◽  
Liquid Holdup ◽  
Dimensionless Numbers ◽  
New Model

Abstract Accurate prediction of pressure gradient in gas wells is the theoretical basis of gas well performance analysis, production optimization and deliquification technologies design. Experiment is the best access to characterize the flow behavior of gas wells. For low-pressure experimental investigation and gas wells, the most difference is the pressure (gas density), which could lead to totally different flow behavior. Dimensionless numbers are often used in the flow pattern maps to account for the flow similarities at different conditions, which means liquid holdup in the high pressure can be also predicted at low pressure conditions if we choose proper dimensionless numbers for pressure scaling up. However, no studies have focused on this point before. Besides, gas wells have high GLR, most empirical models were intended to developed for oil wells, which have greater weight in low GLR, decreasing the accuracy in gas wells. In order to predict the pressure gradient in horizontal gas wells, an experimental investigation of gas-water flow has been conducted. The experimental test matrix was designed to cover all the flow patterns. The experiment was conducted in a 5-m long pipe. The liquid holdup and pressure gradient were measured. Subsequently, the effect of gas velocity, liquid velocity, pipe diameter, and inclined angle on liquid holdup was analyzed. Then the dimensionless numbers proposed in the literature have been investigated and analyzed for pressure scaling up. Finally, a comprehensive model was established, which is developed for prediction pressure drop in gas wells. Some field and experimental data were provided to evaluate the new model. The results show that the Duns-Ros dimensionless number was not proper for pressure scaling up while the Hewitt-Robert Number performs best. Compared to widely used pressure gradient models with field data, the new model with Hewitt-Robert Number performed best, which shows that it is capable of dealing with prediction of pressure gradient in gas wells.

Pressure Effects on Low-Liquid-Loading Oil/Gas Flow in Slightly Upward Inclined Pipes: Flow Pattern, Pressure Gradient, and Liquid Holdup

SPE Journal ◽  
2019 ◽  
Vol 24 (05) ◽  
pp. 2221-2238 ◽  
Author(s):  
Hendy T. Rodrigues ◽  
Eduardo Pereyra ◽  
Cem Sarica
Keyword(s):  
Pressure Gradient ◽  
Flow Pattern ◽  
Slug Flow ◽  
Annular Flow ◽  
Flow Patterns ◽  
Pressure Effects ◽  
Liquid Holdup ◽  
Liquid Loading ◽  
Interfacial Roughness ◽  
Oil Gas

Summary This paper studied the effects of system pressure on oil/gas low–liquid–loading flow in a slightly upward inclined pipe configuration using new experimental data acquired in a high–pressure flow loop. Flow rates are representative of the flow in wet–gas transport pipelines. Results for flow pattern observations, pressure gradient, liquid holdup, and interfacial–roughness measurements were calculated and compared to available predictive models. The experiments were carried out at three system pressures (1.48, 2.17, and 2.86 MPa) in a 0.155–m–inside diameter (ID) pipe inclined at 2° from the horizontal. Isopar™ L oil and nitrogen gas were the working fluids. Liquid superficial velocities ranged from 0.01 to 0.05 m/s, while gas superficial velocities ranged from 1.5 to 16 m/s. Measurements included pressure gradient and liquid holdup. Flow visualization and wire–mesh–sensor (WMS) data were used to identify the flow patterns. Interfacial roughness was obtained from the WMS data. Three flow patterns were observed: pseudo-slug, stratified, and annular. Pseudo-slug is characterized as an intermittent flow where the liquid does not occupy the whole pipe cross section as does a traditional slug flow. In the annular flow pattern, the bulk of the liquid was observed to flow at the pipe bottom in a stratified configuration; however, a thin liquid film covered the whole pipe circumference. In both stratified and annular flow patterns, the interface between the gas core and the bottom liquid film presented a flat shape. The superficial gas Froude number, FrSg, was found to be an important dimensionless parameter to scale the pressure effects on the measured parameters. In the pseudo-slug flow pattern, the flow is gravity–dominated. Pressure gradient is a function of FrSg and liquid superficial velocity, vSL. Liquid holdup is independent of vSL and a function of FrSg. In the stratified and annular flow patterns, the flow is friction–dominated. Both pressure gradient and liquid holdup are functions of FrSg and vSL. Interfacial–roughness measurements showed a small variation in the stratified and annular flow patterns. Model comparison produced mixed results, depending on the specific flow conditions. A relation between the measured interfacial roughness and the interfacial friction factor was proposed, and the results agreed with the existing measurements.

Performance of Two-Phase Flow Models on the Prediction of Oscillatory Flow Conditions

2016 ◽  
Author(s):  
Catalina Posada ◽  
Paulo Waltrich
Keyword(s):  
Experimental Data ◽  
Steady State ◽  
Pressure Gradient ◽  
Two Phase Flow ◽  
Percentage Error ◽  
Phase Flow ◽  
Liquid Holdup ◽  
Two Phase ◽  
Flow Models ◽  
Absolute Percentage Error

The present investigation presents a comparative study between two-phase flow models and experimental data. Experimental data was obtained using a 42 m long, 0.05 m ID tube system. The experimental data include conditions for pressures ranging from 1.2 to 2.8 bara, superficial liquid velocities 0.02–0.3 m/s, and superficial gas velocity ranges 0.17–26 m/s. The experimental data was used to evaluate the performance of steady-state empirical and mechanistic models while estimating liquid holdup and pressure gradient under steady-state and oscillatory conditions. The purpose of this analysis is first to evaluate the accuracy of the models predicting the liquid holdup and pressure gradient under steady-state conditions. Then, after evaluating the models under state-steady conditions, the same models are used to predict the same parameters for oscillatory and periodic conditions for similar gas and liquid velocities. The transient multiphase flow simulator OLGA, which has been widely used in the oil and gas industry, was implemented to model one oscillatory case to evaluate the prediction improvement while using a transient instead of a steady-state model to predict oscillatory flows. For the model with best performance for steady-state pressure gradient prediction, the absolute percentage error is 12% for Uls = 0.02 m/s and 5% for Uls = 0.3. For oscillatory conditions, the absolute percentage error is 30% for Uls = 0.02 m/s and 4% for Uls = 0.3. OLGA results underpredict the experimental pressure gradient under oscillatory conditions with errors up to 30%. Therefore, it was possible to conclude that the models can predict the average of the oscillatory data almost as well as for steady-state conditions.

A Model To Predict Liquid Holdup and Pressure Gradient of Near-Horizontal Wet-Gas Pipelines

2007 ◽  
Vol 2 (02) ◽  
pp. 1-8 ◽  
Author(s):  
Yongqian Fan ◽  
Qian Wang ◽  
Hong-Quan Zhang ◽  
Thomas John Danielson ◽  
Cem Sarica
Keyword(s):  
Pressure Gradient ◽  
Gas Pipelines ◽  
Liquid Holdup ◽  
Wet Gas

A Model To Predict Liquid Holdup and Pressure Gradient of Near-Horizontal Wet-Gas Pipelines

2005 ◽  
Author(s):  
Yongqian Fan ◽  
Qian Wang ◽  
Hong-Quan Zhang ◽  
Cem Sarica ◽  
Thomas John Danielson
Keyword(s):  
Pressure Gradient ◽  
Gas Pipelines ◽  
Liquid Holdup ◽  
Wet Gas
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