Flow Design Bureau (Norway)

The presence of asphaltenes in oil and water emulsions promotes emulsion stability, a major concern in the recovery of oil reserves. A number of mechanisms for this stabilizing effect have been proposed recently, including those that implicate the interfacial rheology of asphaltenes as a primary factor. We present interfacial shear rheological data for asphaltenes at liquid–liquid interfaces and show conclusively that asphaltenes at an oil–water interface exhibit a soft-glassy rheological behavior in agreement with the soft-glassy rheology (SGR) model. This characteristic allows the stabilization of emulsions via mechanical resistance to coalescence.

The adsorption characteristics of Span 80 at liquid/liquid interfaces were investigated. The equilibrium interfacial tension values were successfully fitted with a Langmuir isotherm resulting in the determination of a mean molecular area from 25 to 35 Å2/mol. The measured interfacial tension values and deduced adsorption parameters depend on the experimental technique used to obtain them, either Du Noüy ring or profile analysis tensiometry. Two possible explanations to such phenomenon are provided. Adsorption kinetics of Span 80 at liquid/liquid interfaces were studied, and it was concluded that the diffusion of Span 80 molecules from the bulk is the rate determining step of the adsorption. Finally the interfacial rheology properties were investigated and compared to the Lucassen–van den Tempel model. A good match was obtained when the isotherm parameters determined by profile analysis tensiometry were used.

Abstract Intrusive, erosion-based sand probes, as well as non-intrusive, acoustic sand probes, are commonly used in the oil and gas producing industry. Each system has its advantages and disadvantages, and the choice of technology is most commonly dependent on the flow conditions and the purpose of the monitoring. This paper examines the development of intrusive and non-intrusive sand monitoring as well as more recent market drivers, such as the move towards technology integration; the development of sand management software systems; and how a specialized Windows-based field monitoring software system can enable operators to watch their fields remotely and in more detail and put in place an effective control-based system. The end goal is where acoustic and erosion-based sand sensors can be combined and integrated with new sand management software, leading to increased monitoring, reliability and redundancy, more extensive information, and improved alarm settings. The following paper presents examples of applications and field data from sand monitoring in an offshore field in Norway, where the goal was to put in place a more effective sand monitoring system for erosion-based sand sensors. The system has been used to secure control of massive sand production and to establish maximum sand-free production rates.

As the use of CFD in industrial applications increases, so does the need for verification and validation of the theoretical/numerical results. This paper focuses on tools for validation and in particular, on the use of Particle Imaging Velocimetry (PIV) as such a tool. Diffraction of regular waves due to a single, fixed vertical cylinder is investigated. Theoretical results of wave run-up and wave kinematics are compared to measurements from model tests. Theoretical results are obtained by second order potential theory and by fully non-linear CFD computations. The second order potential theory frequency-domain results are computed by the industry standard code WAMIT, while the fully nonlinear time-domain simulations are performed by the commercial CFD code Flow-3D. Measurements are obtained by means of wave probes, PIV and snapshots taken with a high-speed camera. The experiments are made with the model in place as well as without the model, for validation of the incident flow field. For the identification of non-linear effects, the steepness of the waves is varied. The surface elevation is measured by means of the wave probes, while the PIV equipment measures the kinematics. High quality photos taken by the high-speed camera give a detailed overview of the surface elevation for inspection. In addition to focusing on validation tools, the paper also addresses some critical aspects associated with the CFD computations, such as the modeling of boundary conditions. The work is based partly upon results from the WaveLand JIP, Phase 2.

This paper reviews the issue of making unsteady measurements involving cavitating flow in traditional test loops. Measurements of the dynamic response of a water tunnel during testing of a partially cavitating hydrofoil are presented and reviewed in the context of current theory. Data were collected from an array of pressure transducers that were distributed around the tunnel loop. In the post processing of these data, gain and phase response data were calculated. Theoretical analysis consisted of splitting the system into different elements, and included the compressibility of water in the physics used to describe each element. While solving the global system an eigenvalue solution was found, thus no node specific solution is obtained. This work is currently being extended with the aim of obtaining node specific values such that a more direct comparison between the experimental and theoretical work can be made.