Enabling turbulence dispersion in a computational fluid dynamics simulation of a developing liquid-solid pipe flow leads to a focus of low-Stokes number particles around the pipe axis. This phenomenon is found to concentrate their impacts on a centrally located target surface such that a local erosion spot develops. This result is counter-intuitive as low-Stokes particles are deemed to follow the carrier average streamlines going around the body, which diminishes their probability of impact. This is nevertheless a fact reported experimentally too. Analysis of the simulations reveals that turbulence tends to drive preferentially tiny particles from areas of high to low agitation. This phenomenon is sometimes named as turbophoresis. Long straight piping systems are typical candidates for turbulent pipe flows hosting an annular zone of turbulence that tends to disperse and concentrate fines towards the axis. At the approach of a body, like a cross-flow cylinder, particles may be somewhat re-scattered away by the carrier dragging them around. As such, this turbulence dispersion effect on fines concerns various industrial solid transport systems. Fine impacts concentration is likely to create unexpected, local wear zone.
Sand screens are often installed in sanding prone wellbores to control sand production. A selection of optimal sand screen apertures is required to minimise sand production and maximise fluid production. This has been accomplished historically on empirical correlations, rules of thumb and laboratory sand retention experiments. These methodologies have a number of limitations that can lead to different screen types and sub-optimal screen apertures to be selected. Using discrete element models (DEMs), many design/operating parameters similar to a specific wellbore condition can be simulated and tested in parallel. Most importantly, the detailed particle scale information helps to give a detailed understanding of the underlying mechanisms controlling the sand retention process. This extended abstract presents an investigation of the sand production problem from wire wrapped screens and slotted liners through the use of a DEM for the solid flow with fluid flow coupling using computational fluid dynamics (CFD). Information about particle sizes and distributions incorporated in the DEM model are based on measurement data from reservoir sands. The focus is on the effect of particle size distributions, particle concentration, and the slot width on sand retention across a slotted sand screen.
Sand production may be induced by many factors, such as reservoir pressure depletion, excessive draw-down pressure and water-cut. When transported from the formation, the sand particles can cause serious damage to completion and topside assets, impacting the overall productivity and safety of the operating wells. The sand management strategy for a particular field requires careful planning, evaluation and implementation to ensure effective and safe well productivity. The associated CAPEX and OPEX implications and risks can be high if the sanding problem is not managed carefully. This requires a good understanding of field-specific sanding problems. PETRONAS and CSIRO have collaborated on an integrated research program to provide a better understanding of the critical issue affecting sand production and develop associated predictive tools. This involved a multidisciplinary team from geomechanics, fluid mechanics and mathematics to examine the entire sand production process from sand generation, control and transportation to ensure an optimum sand management strategy. This extended abstract provides an overview of the research methodology based on experimental and numerical modelling techniques supported by field information. The study focuses on sand production behaviour, as well as failure of down-hole sand control equipment. The research led to better prediction and quantification of the sand production propensity, as well as erosion severity on critical production equipment. Insights and operational guidelines were also established to assist production and facility engineers in managing sand production challenges. This integrated research methodology would be applicable to unconventional resource areas, such as coal seam gas or shale gas production.
Standard elbows are used to redirect multiphase flows in oil and gas facilities. Internal erosion of the pipe walls is expected when produced solids are present in the pipe system. The literature widely documents erosion modelling through empirical and numerical methodologies validated with experimental data on elbow erosion. There are no studies documenting the full internal surface of standard elbows in multiphase flow erosion. This peer-reviewed paper fills that knowledge gap through experimental erosion modelling of standard elbows at various multiphase flow conditions. The results provide a source of validation for numerical and analytical methodologies. Surface profiling of standard elbows at gas volume fractions (GVFs) from zero to one are studied. Results suggest that erosion hot spots for all GVFs are located past an angle of approximately 45° from the flow inlet plane. In gas only flows, moderate levels of erosion occur upstream of the erosion hot spot. All GVF conditions exhibit moderate levels of erosion downstream of the erosion hot spot. In liquid only flows, the erosion hot spot is at the extrados in the vicinity of the elbow outlet plane, and is not easily detectable by ultrasonic probes. Comparison of multiphase experimental erosion pattern is made with computational fluid dynamics multiphase erosion simulations. A new relationship between the erosion rate of standard elbows and the reference cylinder-in-pipe data is proposed.
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