Eissa Alsafran - Academia.edu (original) (raw)

Papers by Eissa Alsafran

Journal of Energy Resources Technology, Sep 1, 2008

Journal of Petroleum Science and Engineering, 2014

ABSTRACT Progressing Cavity Pumps (PCP), a type of Moineau pumps, is an artificial lift method of... more ABSTRACT Progressing Cavity Pumps (PCP), a type of Moineau pumps, is an artificial lift method often used for high viscosity and solids producing wells. In this paper, the three-dimensional vector theory and the theory of Hypocycloid were used to give a new modeling insight into the design and performance of PCPs. Specifically, a new design model and procedure of PCPs was developed and described in detail, in addition to a new mathematical model to determine the theoretical pump factor for any given PCP. A Sensitivity analysis was carried out to study the effects of the pump eccentricity, semicircle diameter and motor rotational speed on the pump performance. The results of this study are not only important for manufacturers to optimize PCP’s design, but also for operators to improve the performance and efficiency of such PCPs.

SPE Annual Technical Conference and Exhibition, 2011

A hilly-terrain pipeline consists of horizontal, upward inclined and downward inclined sections. ... more A hilly-terrain pipeline consists of horizontal, upward inclined and downward inclined sections. The lack of understanding of how three-phase slug flow characteristics change in hilly-terrain pipelines may lead to inaccurate modeling of the phenomenon and thus poor pipeline and downstream facility designs. Although several slug tracking models are available, their performance has not been thoroughly tested against gas-oil-water data in hilly-terrain pipelines due to the scarcity of such data.

Engineering Technology Conference on Energy, Parts A and B, 2002

SPE Annual Technical Conference and Exhibition, 2008

Dielectric and petrophysical data for both carbonate and sandstone brine-saturated rocks have bee... more Dielectric and petrophysical data for both carbonate and sandstone brine-saturated rocks have been used in a discriminant analysis for the purpose of developing a model for rock-type classification. A total of eight petrophysical and dielectric parameters were used in this study. The petrophysical parameters consist of a cation exchange capacity (CEC), a specific surface area (SA) and a rock porosity (φ). The dielectric parameters deduced from the impedance measurements consist of ζ s and ζ ∞ , which are real numbers representing the static and the high-frequency relative dielectric permittivities of the water-saturated rock, respectively, the characteristic relaxation time τ , the spread parameter α and σ s , which is the dc conductivity of the water-saturated rock. Outliers have been identified by computing the squared Mahalanobis distances to centroid. Multivariate data cases with relatively large values of the squared Mahalanobis distance associated with small probabilities in the order of 0.001 or less have been removed. Results of the discriminant analysis indicate that only four variables (ζ s , ζ ∞ , φ, CEC) are sufficient to identify rock types. The analysis reveals the existence of a significant discriminant function to distinguish among two distinct rock types related to two broadly defined lithofacies: sandstones and carbonates. A rock-type classification model based on dielectric permittivity and petrophysical data is, therefore, introduced. The model has been validated by an independent set of testing samples. The results of this study indicate that the use of dielectric permittivity data, in conjunction with basic rock properties such as the porosity and the cation exchange capacity, appears to be a robust approach for hydrocarbon rock-type classification.

Proceedings of Middle East Oil Show and Conference, 1997

ABSTRACT This paper describes design, implementation and performance of powered injection pilot a... more ABSTRACT This paper describes design, implementation and performance of powered injection pilot and dumpflood injection pilot in Oolitic limestone reservoir in Kuwait. For powered water injection, a closed water injection pilot plant was developed in the field with a minimum pressure of 80 psi. Zubair aquifer was used as source water. The injection pressure in excess of 1500 psi was maintained. Decline in the Injectivity of pilot wells was not observed during the injection period and there was no water breakthrough. Pilot dumpflood from Zubair aquifer was also investigated which showed severe erosion/corrosion of tubing in one well. Based on investigations, powered water injection using aquifer water and effluent water will be implemented for full field application.

Journal of Petroleum Science and Engineering, 2009

slug frequency entrance effect slug initiation terrain slugging multiple linear regression

Journal of Petroleum Science and Engineering, 2013

Slug flow is the dominant two-phase flow pattern in horizontal and slightly inclined multiphase t... more Slug flow is the dominant two-phase flow pattern in horizontal and slightly inclined multiphase transport pipelines. Slugs generate and dissipate along pipelines due to the unsteady nature of slug flow, which gives rise to the time-dependent behavior, where the pressure, mass flow and velocity vary with time. The velocity of a newly initiated developing slug exhibits unsteady behavior downstream of the initiation point. The objective of this study is to experimentally investigate the unsteady velocity behavior of newly initiated slugs at a pipeline dip. A further objective is to develop a simple transient model to predict the development of slug velocity in time and space beyond the initiation point. Experimental observations show that pseudo-slugs initiated at the bottom elbow initially accelerate, then decelerate at a region near the uphill pipe section exit. Detailed analysis of the slug velocity distribution shows that the acceleration and deceleration phenomena are related to the slug growth and dissipation along the pipe. Furthermore, the maximum slug velocity is observed approximately at a dimensionless distance (x/D) of 110 from the pipeline dip where slugs are initiated. The investigation of operational and geometrical parameter effects showed that gas and liquid superficial velocities have a significant effect on slug velocity. However, the effect of superficial liquid velocity decreases as the flow develops along the pipeline. The experimental results show that an increase of 11 inclination angle promotes slug acceleration and deceleration trends significantly.

Journal of Geophysics and Engineering, 2009

Journal of Energy Resources Technology, 2004

International Journal of Multiphase Flow, 2005

The objective of this study is to improve the current phenomenological understanding of slug flow... more The objective of this study is to improve the current phenomenological understanding of slug flow characteristics over an entire hilly-terrain section, and in particular, the slug initiation mechanism at the lower dip.

SPE Heavy Oil Conference and Exhibition, 2011

ABSTRACT

Canadian Unconventional Resources Conference, 2011

The translational velocity, velocity of slug units, is one of the key closure relationships in tw... more The translational velocity, velocity of slug units, is one of the key closure relationships in two-phase flow mechanistic modeling. It is described as the summation of the maximum mixture velocity in the slug body and the drift velocity. The existing equation for the drift velocity is developed by using potential flow theory. Surface tension and viscosity are neglected. However, the drift velocity is expected to be affected with high oil viscosity. In this study, the effects of high oil viscosity on drift velocity for horizontal and upward inclined pipes are experimentally observed. The experiments are performed on a flow loop with a test section 50.8 mm ID for inclination angles of 0° to 90°. Water and viscous oil are used as test fluids. Liquid viscosities vary from 0.001 to 1.237 Pa·s.

SPE Projects Facilities & Construction, 2010

ABSTRACT Slug frequency is defined as the number of slugs passing at a specific point along a pip... more ABSTRACT Slug frequency is defined as the number of slugs passing at a specific point along a pipeline over a certain period of time. Most experimental studies related to slug frequency in the literature were conducted using air and water. Data with a viscous liquid phase are scarce. Knowledge of the effect of liquid viscosity on slug flow is crucial to size pipelines and design pre-process equipment. In this study, the effects of high oil viscosity on slug frequency for horizontal pipes are experimentally investigated. The experiments are performed at oil viscosities between 0.181 and 0.589 Pa•s in a horizontal pipe. Experimental results are compared with the existing slug frequency correlations. Experimental observations reveal that slug frequency appears to be a strong function of liquid viscosity. However, existing slug frequency closure models do not show any explicit dependency on liquid viscosity. A closure model taking into account viscosity effects for horizontal pipes on slug frequency is proposed. The proposed slug frequency model is compared against published data. The comparison of proposed closure model against limited published data shows that it is a better alternative than existing correlations for high viscosity oils. The proposed slug frequency closure model can improve the performance of the existing mechanistic models for high viscosity oil applications. Introduction Slug flow is one of the most observed flow patterns that characterize the gas-liquid flow in multiphase transportation pipelines. The most distinctive characteristic of slug flow is its intermittent nature due to a unique phase distribution. It occurs over a wide range of gas and liquid flow rates. Extensive experimental studies have been conducted to understand the mechanism of slug formation. However, very few studies have addressed effect of high viscosity behavior in slug characteristics. Gokcal et al. (2006) observed slug flow to be the dominant flow pattern for the high viscosity oil and gas flows. They found that slug frequency increased while the slug length decreased as the liquid viscosity increased. Prediction of slug frequency is important for design of transportation pipelines and gas-liquid receiving facilities. Slug frequency is required as an input in mechanistic models to predict slug flow characteristics such as pressure gradient and liquid holdup accurately.

SPE Production & Operations, 2008

ABSTRACT Probabilistic/mechanistic modeling was carried out to develop a predictive model for ini... more ABSTRACT Probabilistic/mechanistic modeling was carried out to develop a predictive model for initiated slug-length distribution at the lower elbow of a hilly-terrain pipeline. Statistical analysis suggested the appropriateness of a Log-Normal model over an Inverse Gaussian model. The Log-Normal model is correlated by two empirical relationships developed for mean slug length and slug-length standard deviation. Based on experimental observations, the approach of critical liquid level (instead of critical liquid volume) was adopted as the slug initiation criterion at the lower elbow. Consequently, the critical liquid level was mechanistically modeled and empirically correlated to the initiated mean slug length and standard deviation. A model validation study demonstrated the capability of the probabilistic/mechanistic models to reproduce experimental data with a satisfactory match. The match is improved when the developed correlations were tuned using the statistical confidence intervals of their coefficients.

SPE Production & Operations, 2009

The objective of this study is to develop and validate a theoretical slip model for two-phase flo... more The objective of this study is to develop and validate a theoretical slip model for two-phase flow through chokes. As opposed to the models used currently by the industry, the present model accounts for slippage between the liquid and gas phases as they pass through the choke. The theoretical basis of the model is a 1D balance equation of mass, momentum, and energy with the assumptions of constant quality and incompressible liquid phase. The present slip model is capable of predicting the critical-subcritical-flow boundary and the critical and subcritical mass-flow rates. A model-validation study demonstrated the capability of the slip models to predict the critical-flow boundary with an average error and standard deviation of 5.2% and 15.5%, respectively. Furthermore, in a laboratory validation, the present slip model predicted the mass-flow rate with an average error of 2.7% and 12.5% standard deviation. Compared with field data, the present slip model predicted the mass-flow rate with 1.4% average percent error and 15% standard deviation. Compared to existing no-slip models ; Perkins1993) used commonly by the industry, the present slipmodel predictions outperformed their predictions in the average percent error in both laboratory and field validation and in the standard deviation in the laboratory validation only. This validation result indicates the importance of the slippage phenomenon.

SPE Production & Facilities, 2005

Journal of Energy Resources Technology, 2003

Hilly-terrain pipelines consist of interconnected horizontal, uphill and downhill sections. Slug ... more Hilly-terrain pipelines consist of interconnected horizontal, uphill and downhill sections. Slug flow experiences a transition from one state to another as the pipe inclination angle changes. Normally, slugs dissipate if the upward inclination becomes smaller or the ...