Design, Execution, and Results of the First Multizone Cased Hole Gravel-Pack Completion in West Malaysia
This paper illustrates the design and application of tools and
procedures for successful execution of the first multizone cased hole
gravel-pack completion in West Malaysia utilizing Alternate Path (shunt tube)
technology with isolation system to enable access to multiple reserves and
maximize reservoir contact in “A” field.
The single-trip gravel-pack system allowed multiple stacked zones to be
completed with reduced completion operation time. The “A” field,
predominantly consisting of unconsolidated stacked layers, has tendency to
produce formation fines and sand and historically, gravel pack has proved as
the most appropriate sand exclusion method for this field. Considering the
distance between the adjacent zones (upper zone was approximately 120 m
distance from the middle zone), shunt tube technique was selected as the most
suitable method for achieving uniform and high packing efficiency.
Several options were examined for the completion to select a te chnology
to have a proven cost-effective solution to cope with different intervals space
out far distance. The multizone shunt tube system has an intensive record of
accomplishment in the oil and gas industry and has been used in Malaysia with
excellent results. It was a very attractive technique to use because of its
simplicity and cost-effective approach of completion of multiple intervals.
Proppant placement with 100% packing efficiency along 227 m of three different
zones was critical for the success of the project. Shunt tube configuration was
optimized by selectively plugging and unplugging nozzles to efficiently
distribute the proppant to all three intervals. This technique added high value
to the success of the operation and ensured any bridges in the annulus were
bypassed during gravel-packing treatment.
The gravel-packing carrier fluid also plays an important role when using
shunt tubes. The system needs a viscous fluid to suspend and carry proppants to
the perforations and form a competent and compacted pack without damaging the
treated zones. For this reason, a nonpolymeric and solid-free VES (viscous
elastic surfactant) was chosen. The selected carrier fluid has been used in
propped fracturing as well as gravel packing with excellent results as it has
exceptional gravel carrying capability and leaves high formation retained
permeability, resulting in significantly low skin due to the unique capability
of breaking when exposed to small amount of liquid hydrocarbons, thus
eliminating the requirement for breakers (Sullivan et al., 2006; Parra et al.,
2009; Shahryar et al., 2010).