The post-injection phase of the Tomakomai CCS Demonstration Project

Abstract

The Tomakomai CCS Demonstration Project is an offshore CCS project being conducted in the busy port area of Tomakomai City, Hokkaido Prefecture, Japan. The Tomakomai Project has been conducted since JFY 2012* over eleven years, comprised of four years of construction, three years and eight months of CO2 injection and ongoing post injection monitoring. The CO2 source is offgas from a hydrogen production unit of an oil refinery adjacent to the CO2 capture and injection facility on the coastal area where gaseous CO2 was captured by an activated amine process, compressed and injected through two highly deviated injection wells into two offshore reservoirs, namely, the sandstone layers of the Lower Quaternary Moebetsu formation and the volcanic and volcaniclastic rocks of the Miocene Takinoue formation. CO2 injection into the Moebetsu formation began in April 2016 and was terminated in November 2019 with the cumulative amount at 300,012 tonnes. The cumulative CO2 injection into the Takinoue formation ended in 98 tonnes due to low permeability. Comprehensive offshore and onshore monitoring facilities comprised of three observation wells, an OBC, four OBSs and an onshore seismic station were deployed, and the monitoring for seismicity and pressure/temperature of the reservoirs started in February 2015, fourteen months before the start of CO2 injection into the Moebetsu formation. Since the start of monitoring, no seismicity has been detected at and around the reservoirs before, during and after CO2 injection. Four monitor seismic surveys conducted from July 2017, during the CO2 injection, to August 2020, eight months after the termination of the CO2 injection detected growth and stagnation of the amplitude anomalies indicating the evolution of the CO2 plume in the Moebetsu formation. Seasonal marine environmental surveys have been conducted before, during and after the CO2 injection, and no indications of seepage of the injected CO2 into the ocean have been detected. After JFY2021 some monitoring items were optimized and discontinued. (*JFY denotes April of calendar year to March of following year)

Keywords: CCS, offshore, deviated injection well, micro seismicity, seismic survey, marine environmental survey, post-injection

JEL Classification: Z