52 research outputs found
Prediction of sanding in subsurface hydrocarbon reservoirs.
Sand production in oil and gas wells can occur if the fluid velocity exceeds a
certain value. Due to drilling operations, the mechanical stresses can exceed the load bearing capacity of the rock. As the local stresses exceed certain level, a certain amount of rock is fractured into sand. Then, the sand is carried by the fluid through the wellbore depending on the flow rate. The amount of the solids can be less than a few grams per cubic meter of reservoir fluid or an essential amount. In the later case erosion of the rock and removing sufficient quantities of rock can occur. This can produce subsurface cavities which collapse and destroy the well.
When sanding is unavoidable it is necessary to estimate the characteristics of the process. Our aim was to generate a simple one-dimensional local model, which predicts the volume of sanding, the radius and the porosity of the yielded zone. Such model will help the company in the development of complex 3D models
muCool: A novel low-energy muon beam for future precision experiments
Experiments with muons () and muonium atoms () offer
several promising possibilities for testing fundamental symmetries. Examples of
such experiments include search for muon electric dipole moment, measurement of
muon and experiments with muonium from laser spectroscopy to gravity
experiments. These experiments require high quality muon beams with small
transverse size and high intensity at low energy.
At the Paul Scherrer Institute, Switzerland, we are developing a novel device
that reduces the phase space of a standard beam by a factor of
with efficiency. The phase space compression is achieved by
stopping a standard beam in a cryogenic helium gas. The stopped
are manipulated into a small spot with complex electric and magnetic
fields in combination with gas density gradients. From here, the muons are
extracted into the vacuum and into a field-free region. Various aspects of this
compression scheme have been demonstrated. In this article the current status
will be reported.Comment: 8 pages, 5 figures, TCP 2018 conference proceeding
Research Proposal for an Experiment to Search for the Decay {\mu} -> eee
We propose an experiment (Mu3e) to search for the lepton flavour violating
decay mu+ -> e+e-e+. We aim for an ultimate sensitivity of one in 10^16
mu-decays, four orders of magnitude better than previous searches. This
sensitivity is made possible by exploiting modern silicon pixel detectors
providing high spatial resolution and hodoscopes using scintillating fibres and
tiles providing precise timing information at high particle rates.Comment: Research proposal submitted to the Paul Scherrer Institute Research
Committee for Particle Physics at the Ring Cyclotron, 104 page
MEG Upgrade Proposal
We propose the continuation of the MEG experiment to search for the charged
lepton flavour violating decay (cLFV) \mu \to e \gamma, based on an upgrade of
the experiment, which aims for a sensitivity enhancement of one order of
magnitude compared to the final MEG result, down to the
level. The key features of this new MEG upgrade are an increased rate
capability of all detectors to enable running at the intensity frontier and
improved energy, angular and timing resolutions, for both the positron and
photon arms of the detector. On the positron-side a new low-mass, single
volume, high granularity tracker is envisaged, in combination with a new highly
segmented, fast timing counter array, to track positron from a thinner stopping
target. The photon-arm, with the largest liquid xenon (LXe) detector in the
world, totalling 900 l, will also be improved by increasing the granularity at
the incident face, by replacing the current photomultiplier tubes (PMTs) with a
larger number of smaller photosensors and optimizing the photosensor layout
also on the lateral faces. A new DAQ scheme involving the implementation of a
new combined readout board capable of integrating the diverse functions of
digitization, trigger capability and splitter functionality into one condensed
unit, is also under development. We describe here the status of the MEG
experiment, the scientific merits of the upgrade and the experimental methods
we plan to use.Comment: A. M. Baldini and T. Mori Spokespersons. Research proposal submitted
to the Paul Scherrer Institute Research Committee for Particle Physics at the
Ring Cyclotron. 131 Page
Nanopowder management and control of plasma parameters in electronegative SiH4 plasmas
Management of nanosize powder particles via control of plasma parameters in a low-pressure SiH4
discharge for silicon microfabrication technologies is considered. The spatial profiles of electron and
positive/negative ion number densities, electron temperature, and charge of the fine particles are
obtained using a self-consistent fluid model of the electronegative plasmas in the parallel plate
reactor geometry. The model accounts for variable powder size and number density, powder-charge
distribution, local plasma nonuniformity, as well as UV photodetachment of electrons from the
nanoparticles. The relations between the equilibrium discharge state and powder properties and the
input power and neutral gas pressure are studied. Methods for controlling the electron temperature
and SiH3- anion (here assumed to be the powder precursor) density, and hence the powder growth
process, are proposed. It is shown that by controlling the neutral gas pressure, input power, and
powder size and density, plasma density profiles with high levels of uniformity can be achieved.
Management of powder charge distribution is also possible through control of the external
parameters
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