October 21-26, 2018

High-resolution 3D seismic acquisition at theTomakomai CO2 storage project, offshore
Hokkaido, Japan
111T.A. Meckel , Y.E. Feng , R.H. Trevino
1Gulf Coast Carbon Center, Bureau of Economic Geology, The University of Texas at Austin

Monitoring injected CO2 is an important part of assuring permanence of long term storage tomitigate atmospheric emissions. Three-dimensional (3D) seismic has been shown to be aneffective technology for visualizing and measuring subsurface geology and fluids.
In this study, we demonstrate the acquisition, processing and initial interpretation of a highresolution 3D (HR3D) seismic survey in Tomakomai, offshore Japan, above an active offshore
CO2 injection site [1]. The successful deployment of this novel marine seismic monitoring
technology validates HR3D as an appropriate characterization and monitoring tool for largedemonstration and commercial-scale offshore Carbon Capture and Storage (CCS) sites.

As the first application of marine HR3D seismic technology
for CCS monitoring, the goal of the HR3D deployment is tovalidate the technology for CCS projects monitoring in thefollowing ways: 1) mapping of the geologic overburden
above the injection interval in high resolution; 2) attempt toimage CO2 injected into the storage reservoir at
approximately 1,000 meters below the seafloor; and 3) toevaluate repeatability to inform capabilities for time-lapse
studies comparing multiple HR3D acquisitions. The survey
location is 1 to 3.5 km offshore Tomakomai city in Hokkaido
with water depth of 10 to 35 m, where a CO2 injection
operation has been conducted by JCCS as the first integrated
industrial demonstration project of offshore CCS in Japan.

The array design in Tomakomai HR3Dsurvey comprised 4 streamers thatare 25 m in length with 10 m inline
separation. Each streamer has 8channels with a 3.125 m groupinterval, yielding a very small final bin
size of 3 x 3 m. Source and receiver
positioning were achieved using 5rGPS units in the water and a DGPS
antennae on the vessel.

A 210 cubic inch GI airgun was used
as an acoustic source. Over a periodof 6 days, approximately 2 square
kilometres of data were acquired
during daylight hours.

Parameters
Streamers
ChannelsInter-streamer spacingGroup interval
SourceInline shot spacingBin size

Specification
4 x 25 m
8 per streamer = 32 total
10 m
3.125 m210 cubic inch GI Airgun
6.25 m
3x3m

HR3D uses closely spaced, short-offset streamers to achieve high resolution of typically theupper kilometer of stratigraphy [2]. However, the short offset and low-fold coverage creates
new challenges in seismic data processing, which demands a different data processing workflow
tailored to the HR3D acquisition.

We designed a unique processing workflow which involves four
software packages:

The final processed volume images down to 1000 ms two-way travel time (TWTT). In totaleight horizons have been interpreted to date, including seven continuous horizons (H1 to H7)
and an erosional horizon beneath H2, which is characterized by multiple channelized systems.

• RadExPro – used for merging navigation P190 files, geometry
setup, and basic data processing

The anticipated generally
horizontal stratigraphy isobserved, and various
recognizable geologicalfeatures are shown ingreat detail in the first 70
ms. No major faults areobserved throughout thesurvey area. The figure on
the left shows an exampleof time slice at 47 ms
blending with amplitude
and dip-steered similarity
attributes.

• Madagascar – performed interpolation and post-stack phaseshift migration• Paradigm Echos – for prestack footprint removal and stacking• OpendTect – provided dip-steered median filter to suppress
acquisition footprint and random noise, and dip-steeredsimilarity volume for fault detection
Before and after phase-shift migration in Madagascar.
Tributaries are shown after migration with enhanced definition

This study demonstrates the successful acquisition, processing and interpretation of a shallow
marine HR3D seismic data, for the first time deployed over an active offshore CO2 injection site.
The effective deployment of this novel marine seismic monitoring technology validates HR3D tobe an appropriate monitoring tool for large-demonstration and commercial-scale CCS sites.

ACKNOWLEDGEMENTS
Before and after using a F-K filter applied on NMO-correct
shot gathers for linear noise removal

The authors appreciate the Japan Ministry of Economy, Trade and Industry and Japan CCS Co., Ltd for being givena chance to acquire HR3D data at the Tomakomai CCS site. The authors also thank JGI, Inc. for collaboration,mobilization, and providing GPS locations of sources and receivers.
This material is based upon work supported by the U.S. Department of Energy – National Energy Technology
Laboratory, under award agreement DE-FE0028193 DOE-Validation of MVA Tools for Offshore CCS: Novel UltraHigh-Resolution 3D Marine Seismic Technology (P-Cable).

REFERENCES
1. Tanaka, Y., Y. Sawada, D. Tanase, J. Tanaka, S. Shiomi, T. Kasukawa, 2017, Tomakomai CCS demonstration projectof Japan, injection in process, Energy Procedia, 114:5836-5846.
2. Brookshore, B.N., C. Lippus, A. Parish, B. Mattox, and A. Burks, 2016, Dense arrays of short streamers forultrahigh-resolution 3D seismic imaging, The Leading Edge, July 2016: 594-599,
http://dx.doi.org/10.1190/tle35070594.1.