Page 93 - Handbook Of Multiphase Flow Assurance

88 4. Hydraulic and thermal analysis

Increased pressure drop is the most omnipresent effect of multiphase flow. Many operators
try to produce fluid in the same state it is in the reservoir, above the bubble point pressure
in order to avoid the increased pressure loss and reduced production associated with multi-
phase flow. Water injection is one of the methods to maintain the reservoir pressure.
Slug impacts at pipe elbows and tees occur much less often than the increased pressure
drop but these impacts affect production system integrity and have a greater consequence.
Thus this problem is listed at the top of the list.
Deposition of solids such as soft unagglomerated hydrate slush may be accelerated by slug
flow as hydrates are periodically compacted by slug impacts.

Operation online monitoring for pipeline

Online production monitoring tools have been in field use for several decades. These tools
allow the operator to be aware of the process parameters in every location of a production or
an export pipeline without distributed instrumentation. The pressure and temperature trans-
mitters installed at the inlet and outlet of the system along with a detailed model tuned to the
historic flow data allows the monitoring tool to calculate pressure, temperature, flow rate and
liquid holdup at every location along the pipe line.
The production monitoring tools also can provide look-ahead modeling to forecast how
the system will respond to changes in operating parameters. For example, if a pipeline carry-
ing fluid flow is operating in a steady state it may develop certain liquid accumulation or a
holdup. If the flow rate increases, some liquid will be swept downstream. The tool allows to
forecast the time of the swept liquid arrival to the pipe line outlet so that operator can prepare
capacity in the processing facility to accommodate the arriving liquid.

Correlations

The correlations used in the production monitoring tool are the same as the ones used in
multiphase flow analysis tools. Tuning of the correlations may be done individually for each
flow system where the monitoring tool is deployed, to increase it accuracy.

Software
Variety of online monitoring software tools exists based on multiphase flow simulators. A
comparison of some of the commercial flow simulators presented by Dhoorjaty et al. (2018)
shows relative agreement between the investigated commercial and academic models.

Operation online monitoring for well liquids loading and forming
blockages/restrictions

The production monitoring tools may be equipped with modules which detect deviations
from normal parameters and interpret these as blockages, leaks and other upsets in normal
production.