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COMSOL

MODEL HIGHLIGHT: COST-
EFFECTIVE OIL PROCUREMENT
THROUGH MULTILATERAL WELLS

A model built using the COMSOL Multiphysics® software demonstrates the use of
simulation for determining whether mechanical stabilization is needed for a multilateral
well, prior to implementation.

by PHILLIP OBERDORFER

Safe and cost-effective drilling is a major
challenge in the oil and gas industry.
Among the common prospecting risks
are mechanical uncertainties caused by
boreholes, the shafts bored into the
ground for oil extraction. Because drilling
breaks and shifts the rock under the
surface of the earth and pumping creates
mechanical stresses and fluid pressure
in the boreholes, the process must be
planned and studied very carefully to
ensure that the risk of failure or collapse
is minimized.

 èMULTILATERAL WELLS                         FIGURE 3. Simulation results showing the fluid velocity (streamlines) in the hydrocarbon
                                             reservoir and the displacement (surface plot) in the floor and branches of the well.
 One oil-procurement technique developed
 during the last century relies on           by the branching are usually less stable      typical pressures of drilling and pumping,
 multilateral wells with several branches    than a single borehole.                       then it may be assumed that the well
 that split off from a single conduit                                                      will hold up everywhere else, provided
 for pumping oil and natural gas. This          For this reason, these junctions           that the local geological structure in each
 allows easier access and more efficient     sometimes require a liner or casing that
 pumping because several legs can tap        holds the boreholes open and provides         FIGURE 2. Geometry of the multilateral
 into multiple oil zones and navigate        added stability. But this casing adds         well.
 around impermeable regions (see Figure      significantly to the overall cost of a
 1). Although this allows a wider reservoir  drilling project—often by millions of
 area to be covered, the junctions created   dollars. With such a pricetag, it’s vital to
                                             determine whether or not the casing is
 FIGURE 1. Schematic depiction of a          truly necessary before investing in it.
 multilateral well with one branching
 junction, designed for accessing two oil       This is where multiphysics simulation
 reservoirs.                                 comes in. Modeling the branching
                                             junction or junctions in the well can
OIL GAS&                                     provide information about the stability
     comsol news industry focus              of the branch, showing whether the extra
                                             mechanical stabilization is required. It
                                             will also give details about the rest of the
                                             well; if the junctions are stable under the
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