American Oil and Gas Reporter - April 2015 - 104

SpecialReport: Offshore Tech Trends
The Tubular Bells success story began in October 2003, when
BP announced the discovery well in Mississippi Canyon Block
725, 135 miles southeast of New Orleans. The discovery was
drilled to a depth of 31,131 feet and encountered 190 feet of net
oil pay. A successful appraisal well was drilled in 2006, five miles
from the discovery location, followed by two successful sidetracks
in 2007 to further delineate the field. In late 2010, Hess (already
a co-owner in the project) agreed to pay $40 million to acquire
BP's interest and assume operatorship.
"Within a year of becoming operator, Hess sanctioned Tubular Bells for development," McEvilly recounts, noting that one
of the key milestones occurred shortly after project sanctioning,
in October 2011, when Hess signed a facilities agreement with
Williams Partners to construct and operate the Gulfstar One sparbased FPS and related export pipeline system.
The decision to contract with a third-party to build the production facilities helped to accelerate the time to sanction, according to McEvilly. "We delivered first oil safely and on budget in
approximately three years, in spite of all the complexities of a
deepwater subsalt field development (the salt canopy in geologic sections above the reservoir is more than 10,000 feet thick in
some areas). Compared with standards benchmarking, we are very
satisfied with the end result."
Best-In-Class Performance

Hess' best-in-class performance for a major project was made
all the more challenging by middle Miocene reservoir pressures
of about 17,000 psi at well depth and bottom-hole temperatures
that approached 300 degrees Fahrenheit, according to McEvilly. Total vertical depth is 25,000 feet.
"The pressures and temperature have to be accounted for in
the engineering design, but the wells have high deliverability; some
are capable of 25,000-30,000 barrels a day," McEvilly states. "The
reservoir is yielding 35-degree API gravity oil with a gas-to-oil
ratio of approximately 2,000."

"We

delivered ﬁrst oil safely and on budget in
approximately three years, in spite of all the complexities of a deepwater subsalt ﬁeld development.
Compared with standards benchmarking, we are
very satisﬁed with the end result.

MIKE MCEVILLY
Tubular Bells Project Director
Hess Corporation

By mid-March, Hess was producing from three wells at Tubular Bells, and a fourth was being completed and expected to
go on line sometime this year. McEvilly adds that a fifth producing well may be added along with two water injection wells
through 2016.
"There are additional exploitation opportunities and possibilities subsequent to where we are today with Tubular Bells,"
McEvilly reveals. "We started with an underappraised field with
wells on the west and east sides of it. We drilled in the middle
of the field, which proved up and actually exceeded our prognosis to the point that we drilled an additional well to recover the
reserves encountered so far."
Net production to Hess is estimated at 30,000-35,000 barrels
of oil equivalent a day over 2015, with gross production of approximately 59,000 boe/d, he says. Expected net production for
2015 could approach 10 percent of Hess' estimated companywide output of 350,000-360,000 boe/d, representing an increase
of 10-13 percent from pro forma production of 318,000 boe/d
in 2014.
"Originally, we were looking at 25,000 boe/d net at Tubular
Bells this year, but we have upped that by 5,000-10,000 boe/d,"
McEvilly says. "Although gross total recoverable resources are
estimated to exceed 120 million barrels, there are potential future exploitation wells that may improve that."
Floating Production System

The topsides for the Gulfstar One FPS for the Tubular Bells Field
were designed to process 60,000 barrels of oil and 135 MMcf of
gas a day along with up to 60,000 bbl/d of water injection. Shown
here is the main deck lift in May 2013 at Gulf Island Marine Fabricators' construction yard in Houma, La.

104 THE AMERICAN OIL & GAS REPORTER

At the heart of the production system is the Gulfstar One,
stationed in Mississippi Canyon 724. The 584-foot long classic spar hull is mated to a 7,500-ton, three-level topsides structure. The facility's process design accommodates 60,000 barrels of oil a day and 135 million cubic feet of gas a day, along
with the capacity to handle up to 60,000 barrels of water injection a day.
The host facility-including the topsides, hull and export
lines-are owned by Williams Partners (Williams Partners developed the Gulfstar One project and has a 51 percent ownership
interest, with Marubeni Corporation holding a 49 percent interest). Hess has exclusive-use rights to the topsides for the first five
years of service, according to McEvilly.
Heerema Marine Contractor's Balder deepwater construction

American Oil and Gas Reporter - April 2015

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