Masashi Nakatsukasa

Japan Oil, Gas and Metals National Corporation · G&G Division

Monitoring time‐lapse changes in subsurface physical properties of the near‐surface critical zone is increasingly important with respect to climate change, environmental conservation/remediation, geohazard mitigation, and geotechnical engineering activities. Innovative controlled‐source cross‐well seismic monitoring surveys combined with full wavef...

Time-lapse seismic plays an important role in reservoir monitoring. Monitoring of onshore fields is challenging because of insufficient repeatability mainly associated with heterogeneous weathering layers. Permanent monitoring using both stationary sources and sensors can address the problem. However, the number of the sources is very small due to...

Seimic reservoir monitoring is a method to monitor fluid displacement in the reservoir. Long-term monitoring to measure differences over several years has been successful recently. However, short-term monitoring to measure changes in nearly real-time is still challenging because the expected changes in such a short-term are small. Permanent reservo...

Development of shallow subsurface monitoring systems is important for monitoring the ground stability of shallow formation, and also for conventional deep seismic monitoring because with current techniques, temporal changes in shallow seismic velocities can influence monitoring results for the deep subsurface. We have developed an effective shallow...

Time-lapse seismic is often used for reservoir monitoring. Although some case studies have been reported, especially for offshore oil fields, similar onshore Abu Dhabi studies have been limited. Onshore monitoring challenges are mainly due to hard carbonate reservoir rock, in which fluid displacement invokes only minor changes in rock properties. M...

Time-lapse (4D) seismic in onshore Abu Dhabi is extremely challenging. Velocity changes due to fluid displacement are very small: time-lapse P-wave velocity changes after 3 years of CO2 injection are estimated −2% around injection wells. 4D noises are problematic too. Near surface heterogeneities hereafter investigated represent the most dramatic s...

The development of reliable systems for monitoring injected CO2 is essential in carbon capture and storage projects. We applied time-lapse surface-wave analysis to measure temporal variations of the shallow subsurface among 11 periods (0.2 – 21.6 days) of continuous seismic data acquired from 2014 to 2016 at the Aquistore CO2 storage site in Canada...

Repeatability is one of the most important factors for time-lapse seismic surveys. Several types of permanent seismic sources have been developed previously to improve repeatability but monitoring of deep targets is still challenging because of the small power of such sources. We operated an ACROSS (Accurately Controlled, Routinely Operated Signal...

We performed time-lapse surface-wave analysis to monitor the shallow subsurface at the Aquistore CO2 storage site, managed by the Petroleum Technology Research Centre, Canada. A continuous and controlled seismic source system called the Accurately Controlled Routinely Operated Signal System (ACROSS) is used to enhance the temporal resolution and so...

Simultaneous source technique has been increasingly considered as the number of shots increases significantly on recent seismic surveys. We introduce an approach of crosstalk-free simultaneous acquisition using amplitude modulation (AM). Sweep sources are usually repeated many times for enhancing signal-to-noise ratio (S/N). If sweep waveform is ac...

The importance of low-frequency acquisition is widely recognized as it contributes to illumination of deeper targets and estimation of quantitative properties by the use of full waveform inversion. We introduce an approach of low-frequency acquisition using half-cycle pseudorandom sweeps. The waveform is characterized by continuous half-cycle sine...