Page 94 - Handbook Of Multiphase Flow Assurance

Design of oil/gas development project 89

Correlations
The correlations used for detection of blockages rely on the phase transition conditions
and blockage properties for the solids which are more likely to form in a given production
or export pipeline. For example, for the detection of a wax blockage, the wax appearance
temperature as a function of pressure would be used to tell the monitoring tool whether the
wax solid phase is possible or not at a given location in the pipeline. The deviation of pressure
drop may then be interpreted as wax or another type of restriction if wax is not thermody-
namically stable at that location.

Software

The same production monitoring tools can be used to detect the onset of liquids loading
and the forming blockages.

Design of oil/gas development project

The following flow assurance analysis is usually required for the design of a new project.
✓ Steady state line sizing and transient evaluation
° for gas fields
° for gas condensate fields & for volatile oil
° for black oil fields
° for heavy/viscous oil and tar sands production
✓ Steady state line sizing and transient analysis for gas or water reinjection case;
✓ Steady state line sizing for production chemical distribution system
✓ Optimization for the flow assurance mitigation strategy, with account for other issues and
solids (wax, scale, asphaltene, slugs, sand, etc.) that might interfere in the normal production

Hydraulic management
Hydraulic design should optimize both frictional and hydrostatic pressure loss, holdup
accumulation, vibration, water hammer and surge exceeding normal operating parameters
during steady and transient operations. Sensitivity to produced water cut should include as-
sumption for planned and deferred water injection for pressure support, based on reservoir
simulation production profiles.
Operability design should ensure temperature, pressure and flow are within normal oper-
ating limits for the system at any stage in field development life.
Flowlines from trees to manifolds and from manifolds to hubs should be routed predomi-
nantly uphill to minimize pressure losses due to terrain liquids holdup in low spots, in order
to maximize overall recovery, and to avoid slugging to enable uniform subsea chemical dis-
tribution in produced fluid.
Detailed field layout should ensure that both production and chemical injection systems
can operate with acceptable pressure drop and chemical stability in subsurface, subsea,
topsides and export systems conditions.