Two-phase flow in pipelines containing elbows represents a common situation in the oil and gas industries. This study deals with the stratified flow regime between the gas and liquid phase through an elbow. It is of interest to study the change in wave characteristics by measuring the wave velocity and wavelength at the inlet and outlet of the elbow. The experiments were performed under concurrent air-water stratified flow in a horizontal transparent polycarbonate pipe of 0.05m diameter and superficial air and water velocities up to 8.97 and 0.0778 m/s respectively. A non-intrusive video imaging technique was applied to capture the waves. For image analysis, a frame by frame direct overlapping method was used to detect for pulsating flow and a pixel shifting method based on the detection of minimum values in the overlap function was used to determine wave velocity and wavelength. Under superficial gas velocity of less than 4.44 m/s, the results suggest a regular pulsating outflow produced by the elbow. At higher gas velocities, more random pulsation was found and the emergence of localized interfacial waves was detected. Wave velocities measured by this technique were found to produce satisfactory agreement with direct measurements.

In view of the mounting attentiveness on the global warming phenomenon and the rapid evolution of the renewables and sustainables, energy transition is inevitable and oil and gas producers and companies should respond instantly to ensure business resilience. Such a transition puts the fossil fuel industry under unprecedented pressure to cope with serious environmental, technical and economical challenges. The leaders of the industry are in critical need to develop efficient protocols to produce clean energy, reduce costs and improve performance to secure the assets’ value. They also have to effectively respond to the diversified drivers of change through performing holistic and systematic analyses to cover their strategies, operating model and capabilities and collaboration with other industry stakeholders. Operational Excellence (OE) is a thorough, systematic and collaborative approach that addresses the cultural, behavioral and technical transformation within organizations to enable them to streamline operations, perform at optimum limits to achieve their strategic objectives. OE approach, in general, is to be derived from cutting-edge technical advancements needed to improve the ecosystem of the business and to be performed in alignment with a top view on the organization to accommodate the multiple upcoming waves of innovation. Evidently, there is a definite correlation between excellence, innovation and organizational success in growing organically and inorganically. This growth has played a prominent role in shifting activities more toward decentralizing decision making to enable lower-level management and frontline employees to take more ownership of the operations they are responsible for. This paper will share the key elements of an OE model and will demonstrate the impact of unleashing these elements on the performance of oil companies to embark on the journey of energy transition and stay the course.

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The objectives of this study are to conduct a thorough literature review on the subject of multiphase flow through bends and to develop and evaluate a semi-empirical model to determine liquid velocity and pressure loss during stratified gas-liquid flow in a horizontal bend. The model is based on incorporating the momentum balance equations of both phases (air and water). Extensive experiments were carried out to acquire data using air and water in a 0.05 m diameter horizontal pipe simulator with an intermediate bend of 0.5 m radius of curvature.The results show that due to the disturbance nature of the two-phase flow in general, it is quite convenient to describe the pressure drop in terms of the energy loss. It was also found that stratified flow does not cause a significant change in the energy during the flow along the bend traverse due to its stable nature. The semi-empirical model developed for predicting the superficial water velocity during stratified flow shows an acceptable agreement with the experimental data.The work presented in this paper may help flow assurance, production, pipeline and process engineers to have reliable design and operations through counting for the losses caused by such components.

Most hydrocarbons production systems inevitably operate under multiphase flow conditions. While there is an agreement that Navier-Stokes equations govern variables for single-phase flow; there is no such consensus for the multiphase flow yet. Different numerical methods with dissimilar concepts are being conveniently used to simulate multiphase flow systems. Some of these methods do not respect the balance while others damp down strong gradients. The degree of complexity of these models makes the solution practically not reachable by numerical computations despite the fact that many rigorous and systematic studies have been undertaken so far. The essential difficulty is to describe the turbulent interfacial geometry between the multiple phases and take into account steep gradients of the variables across the interface in order to determine the mass, momentum and energy transfers. Different numerical techniques have been developed to simulate the gas-liquid simultaneous flow utilizing the CFD (Computational Fluid Dynamics) discipline. For example, the Volume of Fluid (VOF) model, the Eulerian-Langrangian models and the Eulerian-Eulerian models and combinations between these models. This paper presents the outcomes of numerical investigation carried out to probe the effect of a horizontal bend on the behavioral phenomenon of incompressible air-water simultaneous flow. A 3D CFD code has been developed based on NASA VOF code, which was designed for a different application. Major modifications were implemented on the original program to develop a fit-for-purpose one. The results have been qualified with the experimental data available from a different part of the same project and satisfactory agreements were obtained.