Wax Deposition Rate Research Articles

Transportation technology with pour point depressant and wax deposition in a crude oil pipeline

ABSTRACTThe authors systematically studied transportation technology with pour point depressant and wax deposition in an industrial crude oil pipeline. Experiment results manifest that beneficiated oil acquires obvious modification effect and the reheating temperature of intermediate heat stations should be above 55°C to avoid effect deterioration. Heating schemes are made with lower heating temperature and wider output range. Moreover, an applicable wax deposition model is established to predict wax deposition distribution along the pipeline under various operating conditions. Wax deposition rate varies severely along the pipeline and it is necessary to consider its non-uniformity in production.

Screening of factor influencing wax deposition using full factorial experimental design

ABSTRACTThe purpose of this work was to study the rate of wax deposition of Malaysian crude oil using full factorial design. Important parameters affecting wax deposition such as experimental duration, speed of rotation, cold finger temperature, and inhibitor concentration were investigated. The individual effects of variables and its interaction effects towards the dependent variables were studied. Wax deposit is the dependent variable. The results of the study showed that less wax deposit was obtained (0.75 g) with optimal conditions of initial poly(ethylene-co-vinyl acetate) concentration of 5000 ppm, 2 h duration without rotation speed, and 15°C cold finger temperature. These results demonstrate that cold finger temperature and experimental duration could be the main factors affecting wax deposit formation. The minimum amount of wax deposit obtained could reduce the chances of blocked pipelines; however, crude oil production increased. Nevertheless, Design Expert can be a valuable tool to quantify and detect the special relationships of two of more factors known as interactions regarding how they factors could affect a process, especially for screening purpose.

Prediction of Wax Deposition in an Insulation Crude Oil Pipeline

This study establishes an insulation crude oil pipeline wax deposition experimental device and describes the experimental method for insulation crude oil pipeline wax deposition. The experimental program is based on the operational plan of Tieling–Huludao insulation crude oil pipeline. The data are analyzed according to the effect of varying oil temperature, insulation thickness, and flow on wax deposition. Using SPSS software, a Daqing crude oil wax deposition rate model is derived from the linear regression. The use of the wax deposition rate model forecasts the wax deposition of the Tieling–Huludao insulation crude oil pipeline during different seasons.

The Thermodynamic Model on Paraffin Wax Deposition Prediction

In process of crude oil production and transportation, wax and other solid deposition issues have a significant impact on oilfield production. Solid precipitation not only reduces the production efficiency and increases the cost of production. Therefore, there is a need to study the rate of paraffin wax deposition and cloud point temperature in order to guide the oil field control the paraffin wax deposition. In this paper, we use the Flory theory of polymer solution to correct the liquid activity coefficients, and regular solution theory to correct for the non ideality of the solid mixture, and we consider the impact of isoparaffin. Finally, thermodynamic model is established. The actual example calculation shows that the forecast results of this model are more accurate.

A Reliable Model for Estimating the Wax Deposition Rate During Crude Oil Production and Processing

Deposition of wax in surface and subsurface pipes and even perforations can lead to serious problems including pore spaces blockage, plugging of pipelines, and minimum profitability. Therefore, understanding wax deposition and wax related-properties improves the oil recovery and processing operations in petroleum industry. In this research work, the rate of wax deposition is correlated to a number of main parameters such as the dynamic viscosity of crude oil, shear stress, gradient of wax molecular concentration and temperature difference in pipeline system through implementation of a newly developed model, known as least squares support vector machine (LSSVM) along with the coupled simulated annealing (CSA) optimization strategy. The possible outliers are detected through employing the Leverage technique which involves residual errors plots, Williams' plot, and Hat matrix. The results imply that whole collected real data are in applicability domain of the proposed model. Using a comprehensive statistical investigation, a very good agreement between the predicted LSSVM-CSA outputs and real wax deposition rate is found such that the average relative error percentage and determination coefficient (R2) are 0.048% and 0.999, respectively. Such a study can assist to provide better designs (technically and economically) for underground and surface facilities while dealing with wax deposition cases.

Research on Wax Deposition in the Pipeline Without Pigging for a Long Time

Wax deposits in the pipeline which has been in operation for a long time without conducting pipeline-cleaning job may cause negative consequences: lower transportation efficiency, and even safety risk under certain scenarios. In this study, by using the Wax Deposition Model of China University of Petroleum, the wax deposition rate along the Ren-Jing crude oil pipeline was predicted, and based on the simulation results, the schemes for safe Pipeline Inspection Gauging (Pigging) were laid out to achieve optimum operation. By indoor experiment, we analyzed the effects of temperature and rotation rate on wax deposition. The Wax Deposition Model of China University of Petroleum was verified by comparing to two sets of measurements in field.

Study of Wax Deposition Rate in Waxy Crude Oil Pipeline

In waxy crude oil transportation process, wax crystals start to precipitate as the oil temperature drops to wax appearance point, and then form a network structure gradually which attaches to the wall. The problem of wax deposition seriously affects the normal operation of pipeline. Based on the wax deposition tendency coefficient method, combined with experimental data, the parameters related to wax deposition tendency coefficient is fitted, and the wax deposition rate equation of crude oil is determined finally. The variation law of wax deposition rate along the pipeline is analyzed, and the influence of different seasons and different throughput the on wax deposition rate is discussed subsequently.

The Effect of Magnetic Field on the Deposition of Paraffin Wax on the Oil Pipe

To prevent the deposition of paraffin wax during pipeline transportation, a huge amount of energy was consumed to heat the crude oil every year. So, magnetic paraffin control (MPC) technology was developed as an energy-saving method. In this study, magnetic effects on oil viscosity and wax deposition rate were examined experimentally. Results demonstrate that a decrease of 50% in oil viscosity and a decrease of 87.5% in deposition rate were achieved after magnetic treatment. In addition, the strong dependence of MPC performance on the distance of pipeline transportation as well as oil flow rate is also presented in detail. The present observations shed light on the mechanism of MPC method, and instruct its application on oil pipelines.

Математическое моделирование отложения парафина в нефтепромысловых трубопроводах. Многофазное течение

Background Adequate prediction of wax deposition rate, which allows to plan a variety of preventive and cleaning measures, is important for oil field pipelines operation. Aims and Objectives Development of mathematical model of wax deposition intensity in multiphase flow oil field pipelines. Methods Method is based on solving of equations of conservation of mass, momentum and energy for multiphase multicomponent flows with physical and chemical transformations. Results A mathematical model of the intensity of wax deposition in multiphase oil field pipelines in annular-dispersed regimes is developed. Conclusion The mathematical model of wax deposition accounting non Newtonian properties of waxy oils for multiphase flow is developed.

Predicting temperature distribution in the waxy oil-gas pipe flow

In the simulation of waxy oil–gas pipeline multiphase flow, the physical parameters and rheological properties of the multiphase fluid are the sensitivity functions of the temperature. The precise temperature distribution of multiphase fluid is the foundation of predicting the pressure distribution accurately, wax deposition rate, optimized design and operating analysis of waxy oil and gas pipeline, and so on. Based on the energy equation of oil–gas flow in pipeline, the explicit temperature drop formula (ETDF) for oil–gas steady state calculation is derived from the energy conservation analysis in micro-element. This new energy equation has considered many factors, such as heat transfer with the surroundings along the line, Joule–Thomson effect and impact of terrain undulation to potential energy. So it is an overall form of energy equation, which could reflect the actual fact of multiphase pipeline accurately. Elimination of temperature iteration loop and integration of the explicit temperature equation, instead of enthalpy energy equation, into the conjugated hydraulic and thermal computation have been found to improve the efficiency of algorithm. The calculation program of temperature drops of waxy oil–gas flow in pipelines is compiled on the basis of the ETDF employing modification of the specific heat of the waxy oil. This model is carried out with a practical waxy oil–gas two phase flow pipeline, and the temperature results are compared with OLGA. It is shown that this model has simulated the temperature distribution very well.

The Effect of Operating Temperatures on Wax Deposition

In this study, a deposition model called the Michigan Wax Predictor (MWP) was used to establish criteria as to whether the rate of wax deposition increases or decreases as the oil/coolant temperature is changed in a series of flow-loop experiments. The model was able to predict the effects of the temperature conditions on wax deposition without applying any adjustable parameters. Despite the fact that many previous studies have used the “thermal driving force” to characterize the effect of temperature on wax deposition, it was not the most comprehensive predictive parameter, as it neglects the importance of the solubility curve on wax deposition. This study has revealed that the most important factors affecting deposition are the mass driving force and the shape of the solubility curve. The major impact of the shape of the solubility curve is to affect the change in characteristic mass flux for wax deposition the when the oil and the coolant temperatures are changed. In particular, the differences in the ...

An Experimental Study on Wax Deposition of Water in Waxy Crude Oil Emulsions

The key factors affecting wax deposition of water-in-oil emulsion were studied experimentally using a cold finger device. Wax deposition characteristics of emulsions were obtained. The results showed that the wax deposition profile of emulsions as a function of temperature parameters was similar to that of single oil. However, the effect of the extent of water cut on wax deposition was obviously different at different temperatures. Furthermore, the relative mass of deposit was proposed and found independent of water cut, from which wax deposition rate at different water cuts could be predicted and the predicted values were in good agreement with experimental data.

Single-Phase Wax Deposition Experiments

The behavior of waxy crude oils in subsea production lines has been successfully investigated in a 2 in. deposition flow loop. A North Sea waxy gas condensate was used to investigate wax deposition in turbulent single-phase flow under different temperature and flow conditions. A reliable and accurate procedure for determination of wax thickness and wax roughness from pressure drop, weight, and laser measurements has been developed. The laser technique is a new and promising method to measure the spatial distribution of wax thickness, which was not captured by the traditional pressure drop and weighing methods. These experiments have led to an increased understanding of the mechanisms of wax deposition, which is needed to develop more-accurate models based on physical effects. These models are then the basis for a more accurate prediction of the rate of wax deposition in production lines. The main finding is that molecular diffusion is indeed the central mechanism that steers wax deposition but that an acc...

Studies of Wax Deposition Onset in the Case of Indian Crude Oil

Before taking any decision regarding strategies for prevention and remediation of wax deposition problems in the production tubing, pipeline, and process equipment, it is essential to identify the conditions of wax deposition and to predict wax deposition rates. In this article a study on the prediction of wax deposition, different factors affecting the deposition, and the practical applications of laboratory results obtained for characterization of the Indian crude oils have been presented. The waxy crude characterization study was performed on both stock tank crude oil and recombined integrated crude oil. The results of it exemplify the influence of composition, temperature, and pressure on the solid behavior of Indian paraffinic crudes.

Experimental support for the makeup hypothesis in nestling tawny owls (Strix aluco)

Body condition can affect coloration of traits used in sexual selection and parent-offspring communication by inducing rapid internal changes in pigment concentration or aggregation, thickness of collagen arrays, or blood flux. The recent hypothesis proposes an alternative honesty-reinforcing mechanism, with behaviorally mediated deposition of substances on body surfaces (cosmetics) generating covariation between body condition and coloration. In birds, the uropygial gland wax is actively spread on feathers using the bill and changes in its deposition rate may cause rapid changes in bill and plumage coloration. Using tawny owl nestlings, we tested 3 predictions of the makeup hypothesis, namely that 1) quantity of preen wax deposited accounts for variation in bill coloration, 2) an immune stimulation (induced by injection of a lipopolysaccharide [LPS]) impairs uropygial gland wax production, and 3) different intensities of immune stimulations (strong vs. weak stimulations induced by injections of either LPS or phytohemagglutinin [PHA], respectively) and high versus low food availabilities result in different bill colorations. We found that 1) preen wax reduced bill brightness, 2) a challenge with LPS impaired uropygial gland development, and 3) nestlings challenged with LPS had a brighter bill than PHA-injected nestlings, whereas diet manipulation had no significant effect. Altogether, these results suggest that a strong immune challenge may decrease preen wax deposition rate on the bill of nestling birds, at least by impairing gland wax production, which causes a change in bill coloration. Our study therefore highlights that cosmetic colors might signal short-term variation in immunological status.

Simulating Wax Deposition in Pipelines for Flow Assurance

A method is presented for simulating wax deposition in pipelines in which the wax phase is represented as a continuous distribution of n-paraffin components. The thermodynamic properties of the wax are predicted using a previously developed thermodynamic model. We have adopted a mass transfer model to predict the likely rate of wax deposition. Predictions from the model are compared with observations of flow-loop experiments, and predictions for full-scale pipelines are presented. The impact of the removal of deposited wax by shearing is also investigated. We demonstrate the effect of assuming molecular diffusion to be the dominant mechanism of wax deposition, and we also show that not representing the wax with its full n-paraffin distribution leads to serious distortions of the pipeline simulations. Practical software development issues in the implementation of the model are outlined.

Modelling wax diffusion in crude oils: The cold finger device

In this paper we show how to obtain wax diffusivity and solubility values in crude oils from deposition measurements in the cold finger device with stirring. Providing a rather accurate knowledge of such quantities is of great importance in predicting the wax deposition rate in pipelines. We present a mathematical model in which the physical quantities are assumed to be space-independent in the bulk region of the device, because of agitation, so that mass transport occur in relatively thin boundary layers. As a consequence the deposition phenomenon is accelerated with respect to the static device (see [S. Correra, A. Fasano, L. Fusi, M. Primicerio, F. Rosso. Wax diffusivity under given thermal gradient: a mathematical model, to appear on ZAMM]), shortening the duration of experiments. Comparison with some available laboratory measurements shows a satisfactory agreement and the values obtained are in the range of those usually adopted by practitioners.

Novel Organic Solids Deposition and Control Device for Live-Oils: Design and Applications

A novel laboratory-scale flow assurance tool termed an “organic solids deposition and control (OSDC)” device has been developed to assess the potential for and severity of organic solids deposition problems from hydrocarbon fluids at realistic production and/or transportation conditions. The OSDC device is a shear cell based on Couette−Taylor flow with a cylindrical geometry. The shear cell geometric parameters are optimized to maximize the Reynolds number. The OSDC device mimics the typical pipeline production conditions of temperature, pressure, composition, turbulence, shear rate, surface type, and roughness. These key parameters can be accurately and independently controlled, allowing the deposition tests to be conducted over a wide range of conditions. Deposition tests were performed on live waxy and asphaltenic oils. Reproducible deposits have been generated under consistent test conditions. Wax deposition rates from OSDC are comparable to those found in pilot-scale flow loops while using orders of ...

Reliable Wax Predictions for Flow Assurance

A number of wax models currently in use by the oil industry are based on parameters that were empirically determined to match available data for black oils. These data are often not very precise. The recently developed predictive local composition model is, however, a predictive, theoretically well-defined model based on high-accuracy thermodynamic data. The paper describes how the predictive local composition model can be used in conjunction with conventional cubic equations of state to perform wax equilibrium calculations for black oils. Examples are given that show how the model can predict both wax appearance temperature and the amount of wax precipitated at varying temperatures with or without detailed n-paraffin analyses. The examples presented include the effect of pressure on live oils. The improved thermodynamic modeling of wax formation will allow for better prediction of wax deposition rates for flow assurance.

Wax deposition of Bombay high crude oil under flowing conditions

The wax deposition rate of Bombay high crude oil under flowing conditions in a horizontal pipe was studied at different flow rates and at different temperature differentials between the oil and the cold surface. The deposition was found to increase asymptotically with time and reach a final fluctuating value. The time to obtain equilibrium deposition varied with test conditions. A mathematical equation correlating the flow rate and temperature differential with the equilibrium deposition was also developed.