Page 344 - Handbook Of Multiphase Flow Assurance

Computer code (Makogon, 1994, 1997) 343

Rheology
A stress-controlled rheometer can tell at what conditions the flow in presence of solids
begins and ends. This information can be used to help design production systems and to
compare the effects of chemicals on flow assurance solids.
A rheometer may range in cost from few to ten CPMs.
It is impossible to assemble a stress-controlled rheometer without highly specialized ma-
chining equipment and detailed knowledge of its design.

DSC

A differential scanning calorimeter is an expensive piece of laboratory equipment and may
cost as much as two rheometers. This apparatus can tell how much heat is released during
crystallization of flow assurance solids such as hydrate or wax. This information may be use-
ful in planning the heat transfer characteristics of a production system. One usually wants to
retain heat in the system. However, if a blockage such as hydrate already formed, heat from
ambient environment is required to melt it.
It is impossible to assemble a computer-controlled differential scanning calorimeter.
However, it may be possible to assemble a calorimeter using a well-insulated flask and ther-
mometer, and to use compounds such as cyclopentane which form hydrates at atmospheric
pressure to get qualitative understanding of the heat released during hydrate formation, or
heat consumed during hydrate dissociation.

Raman spectroscopy
A Raman spectrometer may is perhaps the most expensive apparatus and may cost as
much as ten differential scanning calorimeters.
Raman spectroscopy allows one to investigate the environment in which molecules exist. It
can tell whether a gas molecules is inside a small or a large cavity of a hydrate crystal.
It is impossible to assemble a Raman spectrometer without highly specialized machining
and optical equipment and a detailed knowledge of its design.

Computer code (Makogon, 1994, 1997)

Program for generating radial distribution function in water

c This program generates radial distribution function for water MD box.
c Input is a name of coordinates file generated by Sybyl named rdf.crd
c and a number of molecules and timesteps in the system.
c Output will be sent to the file rdf.dat as g(r) vs. r.
c Vary shell thickness to achieve smooth g(r).

implicit real*8(a−h,o−z)
real*8 x(1000),y(1000),z(1000),rdf(1000)