18 Offshore October 2017 • www.offshore-mag.com
Petrel updates seismic review
of offshore Ireland licenses
PGS has completed the 40-day, ‘Bréanann’ 3D seismic data survey
over a 2,392-sq km (923-sq mi) area of the northern Porcupine basin, 50
km ( 31 mi) west of the Kerry coast in western Ireland. Roughly 1,400
sq km (540 sq mi) covered license FEL 8/14, operated by Woodside
Energy. According to Woodside’s partner Petrel Resources, water depths
for the survey ranged from 500-1,300 m ( 1,640-4,265 ft), although the
likely water depth for targets in the license is 600-800 m ( 1,968-2,624 ft).
DownUnder GeoSolutions in Australia is currently completing
processing of the PSDM (Pre-Stacked Depth Migration) data, and
interpretation should be completed by year-end.
Woodside will conduct 3D seismic interpretation of pre-rift and
syn-rift unconformities, the aim being to de-risk the primar y identified
targets of Upper Jurassic to Lower Cretaceous age.
This may lead to a well commitment in the license’s second work
phase from August 2018 through August 2022.
Petrel also holds two licensing options (LO) covering 924 sq km
(357 sq mi) of acreage in the same basin. LO 16/24 includes acreage
close to the Connemara oil field discovered by BP in 1983, which
Statoil subsequently attempted to develop.
Reprocessing and re-interpretation is under way of relevant avail-
able seismic and well data not already in Petrel’s database. Petrel says
that it is particularly encouraged at pinch-outs being mapped in the
block 35/1 area which extend into 35/2. The source rock is already
established, as is the presence of good to high quality reser voir sands.
The main risk, as elsewhere in the basin, is seal. Prime targets are at
the Base Cretaceous level.
LO 16/25 covers block 45/27. Petrel’s team of geophysicists is
reprocessing the available historic 2D seismic lines, and the company
hopes to factor in regional insights emerging from programs under
way on neighboring blocks.
CGG begins 3D multi-client
seismic survey in the Gulf of Mexico
CGG has started acquiring its first complementary wide-azimuth
(CWAz) survey, known as AC CWAz, a BroadSeis 3D multi-client
program in the southern Alaminos Canyon in the Gulf of Mexico.
Extending over 130 outer continental shelf blocks and covering
Great White and the recent Whale discovery, AC CWAz is supported
by industr y funding and complements the company’s existing surveys
in the area by adding azimuth and offset coverage to the historic
wide-azimuth data. All the data will be combined and reprocessed
using the latest 3D deghosting, full-waveform inversion, especially
reflection-based FWI, and tilted transverse isotropy imaging tech-
nology. Fast-Trax PSDM products will be available soon after the
completion of acquisition, the company added.
CEO Jean-Georges Malcor said: “Our AC CWAz multi-client survey
builds on the success of the Encontrado survey by extending our
high-quality images across the US portion of the Perdido foldbelt.
This new program will provide the best images available of the com-
plex geology and reservoirs of this highly prospective area. It also
reflects CGG’s commitment to innovate and invest in solutions that
enable our clients to optimize their development plans and evaluate
the exploration potential in this proven region.”
In addition, CGG also recently completed an 11,500-sq km ( 4,440-sq
mi) wide-azimuth (WAZ) survey for PEMEX in the deepwater Per-
dido area of the Gulf of Mexico. The area covered is perpendicularly
adjacent to existing WAZ data and combined imaging of this first
large-scale orthogonal WAZ dataset of the area should significantly
enhance subsalt imaging, CGG claims.
The company delivered a fasttrack TTI RTM image for the first
block of around 5,200 sq km ( 2,007 sq mi) ahead of schedule, assisting
the client’s drilling operations.
This survey also involved the first deployment of Sercel’s QuietSea
next-generation passive acoustic monitoring system in the Mexican sector,
following accreditation from ASEA, Mexico’s oil and gas environmental
authority. It was integrated into the five-vessel WAZ fleet and according
to the company, demonstrated its reliability and ease of use for providing
clear and accurate data on mammal localization during seismic operations.
North Sea trial confirms efficiency
of novel seabed acquisition system
Seismic equipment provider inApril has completed a full-scale sea
trial of its fully integrated node-based seabed seismic acquisition
The trial, conducted in 110 m (361 ft) of water at the Edvard Grieg
field in the Norwegian North Sea, confirmed Venator as the first
seabed-based exploration tool to provide data superior to conventional-towed streamer solutions at competitive rates, inApril claims.
The system involves fully hands-free handling and flexible node
spacing. The six-day test at the Grieg field last month was of the
A3000 node, said to be suitable for deep and shallow water operations.
According to inApril, ‘node-on-a-rope’ deployment speeds of 5-6
knots and retrieval speeds at 3-4 knots were repeatedly achieved,
enabling up to 20 sq km ( 7. 7 sq mi) of full-azimuth data acquisition
per day in exploration mode.
Early results are said to have confirmed the good data quality
delivered during previous sea trials, only achievable by seabed data
acquisition. Data processing will follow over the coming weeks.
inApril claims that more efficient node-based ocean bottom seismic
will provide an optimal solution for oil companies looking to increase
reserves at reasonable costs via targeted exploration and reservoir
characterization data acquisition.
CEO Vidar Hovland added: “The system is flexible and can be
containerized for mobilization to a variety of vessels for a range of
offshore seismic applications and water depths.” •
Location of the AC CWAz survey in the
southern Alaminos Canyon in the Gulf
of Mexico. (Courtesy CGG)