STUDY OF WELL
PRODUCTIVITY OF MULTILATERAL WELLS
IN THE NORTH SEA
SEQUENCES
ABSTRACT
Although thee multilateral wells are not yet
commonly used, their usage is expected to increase due to the advantages they
offer over conventional horizontal and vertical wells. It is anticipated that
well productivity index (P.I.) does increase with wellbore length but up to a
limit because of non-laminar factors reducing productivity gain. However, the
cost of such a well will, accordingly, increase. The objective of this research
is to identify the optimum hole length beyond which the well P.I. in a
particular reservoir will not be significantly improved.
Methodology involves review of some of the
North Sea geological sequences (Brent, Piper and Statfjord). Impact of
reservoir heterogeneity shall be studied via stochastic randomisation of
reservoir properties. Simulation model has been constructed to reflect
multilateral well performance in different selected sand sequences.
Multilateral well performance was studied first in a homogeneous reservoir
model. Different kinds of rock heterogeneity are then added to the simulation
model. The impacts of wellbore diameter, rock permeability and formation
dip-angle have also been studied. The preparation for this work has required
interaction with geologists, production and reservoir engineers.
The aim is tto generate "Type Curves"
for well P.I. improvement, for varying rock property heterogeneity for
different sand sequences, versus length of horizontal wellbore. A relationship
between well P.I. and its wellbore length has been constructed for different
multilateral configurations. Such Type Curves can be used to assist management
for their development decisions.
BY: ASHRAF
MAHGOUB
September 12, 1997