The Prediction of Undersaturated Crude Oil Viscosity: An Artificial Neural Network and Fuzzy Model Approach

Abstract

Viscosity is one of the most important governing parameters of the fluid flow, either in the porous media or in pipelines. So it is important to use an accurate method to calculate the oil viscosity at various operating conditions. In the literature, several empirical correlations have been proposed for predicting undersaturated crude oil viscosity. However these correlations are not able to predict the oil viscosity adequately for a wide range of conditions. An extensive experimental data of undersaturated oil viscosities from different samples of Iranian oil reservoirs was applied to develop an Artificial Neural Network (ANN) model and fuzzy model to predict and calculate the undersaturated oil viscosity. Validity and accuracy of these models has been confirmed by comparing the obtained results of these correlations and with experimental data for Iranian oil samples. It was observed that there is acceptable agreement between the ANN model and fuzzy model results with experimental data.     

Application of grid partitioning based fuzzy inference system as a novel predictor to estimate dynamic viscosity of n-alkane

Abstract

The oil recovery and rate of production are highly dependent on viscosity of reservoir fluid so this term becomes one of the attractive parameters in petroleum engineering. The viscosity of fluid is highly function of composition, temperature, and pressure so in this article, Grid partitioning based Fuzzy inference system approach is utilized as novel predictor to estimate dynamic viscosity of different normal alkanes in the wide range of operational conditions. In order to comparison of model output with actual data, an experimental dataset related to dynamic viscosity of n-alkanes is gathered. The graphical and statistical comparisons between model outputs and experimental data show the high quality performance of predicting algorithm. The coefficients of determination (R²) of training and testing phases are 0.9985 and 0.9980, respectively. The mentioned statistical indexes represent the great accuracy of model in prediction of dynamic viscosity.     

MODELING THE VISCOSITY-TEMPERATURE RELATIONSHIP OF NIGERIAN NIGER-DELTA CRUDE PETROLEUM

Abstract

The viscosity-temperature relationship of Nigerian Niger-Delta crude oils has been modelled using a generalized viscosity correlation developed by Puttagunta et al. (1992) for conventional crude oils. The correlation requires only one viscosity measurement for prediction, and the data fitting makes use of a simple algorithms. Predictions with the correlation yielded results that matched the experimental viscosities accurately.

The correlation was modified by deriving new values of shape-factor and asymptotic limit. The difference in the results obtained with the original and modified correlation is well within the acceptable limits of experimental error, as both matched the experimental data very well with overall average absolute deviations of 2.4% and 2.3%, respectively.     

The Viscosity of Nontraditional Lightweight Completion Fluid at Elevated Temperature and Pressure

Abstract

Experimental viscosity values of nontraditional lightweight completion fluid at pressure and temperature ranges of 0.1 MPa to 4.48 MPa, and of 25°C to 100°C, respectively, were reported. To establish the relationship among viscosity, pressure, and temperature, experimental data were fit to the modification of Mehrotra and Svrcek's equation. The result shows that the model could be used to describe the fluid viscosity over a wide range of pressure and temperature. The calculated what is sum of square error and root mean square error are 0.2135 and 0.08892, respectively. It is also shown that the predicted values from the model are in a good agreement with both the experimental values and field data.     

The Lumping Kinetic Model for the Heavy Oil Catalytic Cracking MIP Process

Abstract

Based on the characteristics of heavy oil catalytic cracking and maximizing iso-paraffins (MIP) process, a 12-lumping kinetic model was developed in this article to simulate the MIP process. According to the published data from a commercial MIP process, 36 kinetic parameters of the model were determined by the stepwise method. The verification result with industrial data showed that the model could predict not only the distribution of products but also the quality of main products and describe the reaction rules of the MIP process correctly.     

A Generalized Formula for Estimating Pure Alkenes Viscosity

Abstract

The importance of liquid viscosity in chemical process design makes it one of the most measured transport properties. Nevertheless, in the pure-component database, no experimental data on liquid viscosity for nearly 50% of the compounds are available. Therefore, prediction methods for liquid viscosity of alkenes over a wide range of absolute temperature for each components are necessary. Moreover, experimental data measured at lower temperatures are often extrapolated to higher temperatures with erroneous results. To improve liquid viscosity prediction of experimental data to temperatures and carbon numbers, we propose an empirical rule for estimating the viscosity of alkenes compounds. A predictive method, based physical properties (absolute temperature and carbon numbers) as its inputs, to correlate liquid viscosity by the statistical analysis is proposed. For a group of 19 compounds, the mean average absolute deviation was 4.6% for 118 data points. These values are better than other predictive methods and show that the statistical analysis model is stable and can be used to obtain good predictions for compounds that were not used in the model calibration.     

Rheological Properties of Asphalt-Plastic Blends

Abstract

In this article, the flow type of two different asphalt-plastic blends has been determined. One of these blends was prepared from the mixture of asphalt-cement that has a penetration degree of 60–70 (AC60-70) and low-density polyethylene (LDPE), and the other was prepared from the mixture of asphalt-cement that has a penetration degree of 150–200 (AC150-200) and low-density polyethylene (LDPE). Also, a model of the variation of the blend viscosity with temperature and concentration has been developed. It was found that this model is in a good agreement with the experimental data obtained and the relative error is calculated as 10–15%.     

Sensitivity Analysis of Major Drilling Parameters on Cuttings Transport during Drilling Highly-inclined Wells

Abstract

In this study, a layered cuttings transport model is developed for high-angle and horizontal wells, which can be used for incompressible non-Newtonian fluids as well as compressible non-Newtonian fluids (i.e., foams). The effects of major drilling parameters, such as flow rate, rate of penetration, fluid density, viscosity, gas ratio, cuttings size, cuttings density, wellbore inclination and eccentricity of the drillsting on cuttings transport efficiency are analyzed. The major findings from this study are, the dominating parameter on wellbore cleaning is the flow rate, and, as the viscosity of the fluid is increased, the thickness of the cuttings bed developed in the wellbore is significantly increasing. Also, cuttings properties, fluid density, wellbore inclination and eccentricity have some influence on cuttings transport.     

THERMAL EFFECT ON THE PERMANENT VISCOSITY OF A SASKATCHEWAN HEAVY OIL

ABSTRACT

Future energy demands will likely cause increased activity towards the recovery of heavy oil using non-conventional means. Most non-conventional attempts to recover Saskatchewan's heavy oil resources have utilized thermal techniques.

This report discusses the permanent viscosity changes which occur when heavy oil.is subjected to thermal processes from 220 to 425°C. It was observed that under closed operating conditions, the oil viscosity drops in a manner which can be modeled by a first order, kinetic reaction model. The rate constant for this reaction varied from 0.3 × 10^?3 to 6.0 × 10^?3 h^?1 depending on temperature and the assumed molecular weights of the model components. These findings closely parallel earlier results.

Experimental observations on thermal effects during opened operating conditions indicate a dramatic and rapid rise In the remaining crude oil viscosity. The oil was observed to increase its permanent absolute viscosity by a factor as high as 21 times its original absolute viscosity. The single product, first order kinetic model was not capable of predicting this rise in oil viscosity. A simple, two product, first order kinetic model was developed and found to fit the data satisfactorily with a rate constant of 0.6 h^?1 for heavy product formation and a rate constant of 0.03?h^?1 for light product formation at 275°C.     

Improved Correlations for Fluid Properties of UAE Crude Oils

Abstract

Empirical correlations to evaluate crude oil fluid properties such as the formation volume factor, bubble point, viscosity, and oil compressibility above the bubble point are used extensively by petroleum and process engineers to perform calculations for subsurface and surface processes. The published correlations are mostly based on regional data, such as Standing's for California crudes, Petrosky and Farshad's for Gulf of Mexico crudes, and Glaso's for North Sea crudes. Use of these regional correlations is more appropriate for crudes from the same basins for which the correlation is derived. Other correlations, such as the Vasquez and Beggs correlation, are based on data from a very large number of samples coming from multiple regions. Eventhough one is tempted to use these “universal” correlations, the range of error for their predictions is, however, typically large due to the scatter involved in using a large number of data sets to generate these correlations. The UAE fields are quite significant and constitute around 9% of worldwide reserves. In this work, experimental PVT measurements from 15 medium to large fields located in the UAE are used to test the viability of using either regional or universal correlations to UAE crudes. In addition, a new set of empirical correlations is constructed based on these data, and their predictions are also compared. Statistical comparisons indicate that the new correlations developed in this paper reduce the error involved in predicting the bubble point pressures, the oil compressibility, and the oil formation volume factor to less than half the range associated with either the regional or the universal correlations. Also, new correlations for viscosity both at the bubble point and above the bubble point were constructed that gave better predictions for UAE oils over other commonly used correlations for viscosity.     

A Model for Blending Properties of Diesel Oils and Its Optimization Application

Abstract

Property prediction models are important for optimizing the blending ratio of diesel oils. Based on experiments of different blending ratios, published prediction models for freezing point were modified, a published model for cetane number was checked, and a new model for cold filter plugging point was developed. The accuracy of model prediction was quite good. Based on these models, a nonlinear programming method is more suitable for the ratio optimization of blending that makes the best use of poor blending components.     

Proposing a novel and accurate model for forecasting dynamic viscosity of n-alkane in operational conditions

Abstract

The viscosity of fluid is known as resistivity of fluid to flow and straightly affected by temperature and pressure. As it is obvious, the viscosity of reservoir fluid is known as one of the critical parameters which extensively effect on production. Therefore, in the present paper, multilayer perceptron artificial neural network (MLP-ANN) is used as a novel and accurate model to predict dynamic viscosity of normal alkanes in the operational conditions. To this end, 228 dynamic viscosity points as function of carbon number of n-alkane, temperature, and pressure were collected from a reliable paper. The comparison between MLP-ANN outputs and experimental dynamic viscosities is performed in graphical and statistical manners. The calculated coefficients of determination 0.99739 and 0.99051 for training and testing phases express the great ability of MLP-ANN algorithm in prediction of dynamic viscosity of n-alkane. According to the analysis, MLP-ANN has enough accuracy and potential to be used as software for which applicable in petroleum industry.     

A Model for the Estimation of Viscosity of Pure Hydrocarbon Liquids

 

A simple model is developed for the estimation of viscosity of hydrocarbon liquids considering that drag on molecular motion due to thermal energy is balanced by intermolecular attractions. The model equation is validated with National Institute of Standards and Technology data on hydrocarbon liquids (C₃-C₁₀ and C₁₂) considering the effect of molecular shape on drag force. The molecular shape is correlated well with molecular weight of hydrocarbon liquids. The accuracy of the proposed model equation is compared with the correlation. The result showed that the proposed model is more accurate. The proposed model equation predicts the viscosity over a wide range of temperature for C₃-C₂₅ with overall absolute average deviation of 5.13%.     

VISCOSITY OF WATER IN OIL EMULSIONS

ABSTRACT

Increase in water cut in oil fields generally calls for an increase in the capacity of transport pipelines. Proper design and operation of the latter requires good knowledge of the thermophysical properties of flow resistance of crude-oil water mixtures. An experimental program aimed at measurements of oil-water emulsion viscosity for water cuts prior to the inversion point was conducted.

The present work reports on measurements of Nimr crude oil-water mixtures viscosity for different water cuts and a typical range of temperatures representative of field conditions (20°-50°C). Three mixing intensities of 10⁶, 5×10⁶ and 15×10⁶ erg/cm-sec generated by a dynamic coalescer and directly relevant to field conditions were used.

The results suggest that the inversion point occurs around a value of water cut of 35%. Both Newtonian and non-Newtonian (pseudo-plastic) behaviour were observed, and the ASTM viscosity model is found to be applicable to the emulsions. The effect of the mixing intensity on the resulting emulsion viscosity was found to be important at low temperatures and decreased at high temperatures. The experimental data fitted the available correlations in the literature.     

Effects of Temperature and Pressure on Natural Gas Viscosity Which Has Different API Gravities

Abstract

The theory of gas transport is simply stated, but it is quite complex to express in equations that can be used directly to calculate viscosity. A correlation was developed to predict viscosity of natural gas (of different API gravities) function of temperature and pressure. This correlation depends only on API gravity of natural gas. The proposed correlation has been verified using data of about 246 data points, and it is shows significantly better correlation, with an average absolute error of 3.2%.     

Viscosity Model for Petroleum Gases

Abstract

The production processes for petroleum gases employ a broad range of simulation packages to reduce capital, time, and cost associated with actual recovery and pipeline transportation. Viscosity model is an important component of these packages. In this work, we have presented an empirical model for predicting the viscosity of petroleum gases, developed from the three-parameter Yaws equation. New constants were derived for various petroleum gases, as well as for gaseous carbon dioxide. Results obtained with the new model were compared with the viscosity predictions from the Yaws model, and the Miadonye and Clyburn correlation. For four petroleum gases and carbon dioxide at temperatures of 110 K to 1,500 K, the model gave an excellent viscosity prediction with overall average absolute deviations of 0.34% and 0.98%, respectively. The model is simple to incorporate into design and simulation packages, and more accurate than any correlation currently used in petroleum industry for predicting the viscosities of petroleum gases.     

Application of the PR-EOS with C7+ Splitting to Model Fluid Properties in a Large Two-Phase Petroleum Reservoir

Abstract

The use of equations of state (EOS) to model fluid properties is necessary in order to have an internally consistent set of PVT properties, which is essential, especially, when it is desired to use compositional simulators to model two-phase reservoirs. In this article, the 3-parameter Peng-Robinson equation of state along with single carbon number (SCN) splitting of the C₇₊ fraction are used to model a major onshore reservoir in Abu Dhabi that has horizontal and vertical fluid properties variations. Extensive screening and checking of PVT data of the field was necessary to develop this model. Also, extensive verification of the developed model was accomplished by comparing its results to data external to the model. Results of this article indicate the capability of using multiple well PVT analysis within the three-parameter Peng-Robinson EOS to model complex two-phase reservoirs such as this one. We describe the process of building up the model and the challenges involved in performing this task, which include proper selection of representative experimental data to build the model, along with extensive screening and data quality these data, and the model verification so that we have the confidence that one EOS model that can predict the reservoir fluid PVT properties.     

A New Unified Model for Predicting Non-Newtonian Viscosity of Waxy Crudes

Abstract

Viscosity determination in the non-Newtonian regime has always been a major problem in the oil industry. This is due to its dependence on the wax precipitated shear and thermal history of the crude oil. The present shear rate dependent viscosity model was developed by applying the theory of suspension rheology. This model is characterized by its capacity to predict viscosities of crude oils with different shear and thermal history and those containing petroleum-based diluents. Once viscosities at two temperatures above the wax appearance temperature (WAT) and apparent viscosity in the non Newtonian regime are known, viscosities or apparent viscosities at any temperature above the gel point can be determined by using the model together with the concentration of precipitated wax at the specified temperature. Verification of the model by using two Nigerian crudes with different shear and thermal histories and two crudes obtained from the literature shows that the model predicts viscosities with an average absolute deviation of 4.9%.     

A TWO PARAMETER CORRELATION FOR PETROLEUM BITUMENS

ABSTRACT

The viscosity data for a number of bitumen samples obtained from Russian crudes have been correlated. The model equation of viscosity with softening point contains two empirical parameters which were determined by linear regression method by the use of a computer. The viscosity of the 71 samples at 140°C varied from 37.6 to 80,000 mPa.s for the softening point range of 36 to 90°C respectively. The empirical equation gave a very good representation of the softening point -viscosity relationship for the range of bitumens of 40-60°C softening point. The average absolute deviation and the standard error were less than 8% over a wide softening point range.     

MATHEMATICAL MODELLING OF THE RHEOLOGICAL PROPERTIES OF PETROLEUM BITUMENS

ABSTRACT

Three main rheological properties of petroleum bitumens were investigated with the aim of developing a suitable model for the determination of a quality parameter. Two mathematical models have been proposed; one relates softening point to penetration while the other correlates softening point and viscosity. Comparison of the two models with another previously developed model shows that the softening point/viscosity model produces the best results. It also has a great advantage since viscosity can be more accurately measured than penetration and on-line quality control can be effected through viscosity within a few seconds The results of this investigation justify the objective of finding a system of parameters relating the rheological characteristics of bitumens with the generally accepted criteria.