17:15 〜 18:45
[HSC07-P04] Feasibility study of the monitoring system for CO2 plume using Surface Orbital Vibrators and Distributed Acoustic Sensor deployed on an injection well
キーワード：CO2地中貯留、CO2プルームのモニタリング、分布式音響計測（DAS）、地表設置回転型発振器（SOV）、繰り返し地震探査
For geological carbon storage projects, monitoring is essential to ensure that the injected CO2 was contained in the target reservoir. Seismic methods are used as standard techniques for the monitoring. For the requirements of the long-term monitoring, cost-efficient methods are preferable. Recently, a highly reliable and cost-effective method based on the combination of permanent surface orbital vibrators (SOVs) and distributed acoustic sensing (DAS) has been tested. In this paper, we examine the detectivity of CO2 plume by SOV-DAS/VSP technique.
We consider the monitoring layout at the Red Trail Energy (RTE) project in North Dakota, USA, where 180 kt of CO2 are storing annuary in a deep saline layer at the depth of 2000 m. There are one injection well and a monitoring well which are penetrating the target reservoir. DAS fibers were installed behind the casing of these wells. Four of SOVs were installed on the surface on the cross section including the wells. SOVs can operate on daily basis to acquire good S/N data by DAS fibers on the wells.
For the evaluation of the survey, we firstly studied the behavior of injected CO2 in the reservoir. Using the log data at the injection well, we constructed an axisymmetric petrophysical model. Two-phase flow simulation was carried out using TOUGH2. The simulation results indicated that, 1) radius of CO2 became larger at high permeability layer, 2) CO2 was injected from the upper part of the perforation intervals, and 3) CO2 plume could be migrated from the perforation intervals up to the top of the reservoir. Secondly, we calculated wave form from the SOVs to confirm the effect of CO2 in the reservoir. The simulated results indicated that, a) the P-wave was delayed a few msec at the near offset survey layout, and b) the effect of the CO2 plume could be detectable even at the far offset layout when the CO2 plume becomes larger.
These results suggest that SOV-DAS/VSP is useful for the monitoring of geological CO2 storage. The simulated results also provide us information for the cost-effective monitoring.
We consider the monitoring layout at the Red Trail Energy (RTE) project in North Dakota, USA, where 180 kt of CO2 are storing annuary in a deep saline layer at the depth of 2000 m. There are one injection well and a monitoring well which are penetrating the target reservoir. DAS fibers were installed behind the casing of these wells. Four of SOVs were installed on the surface on the cross section including the wells. SOVs can operate on daily basis to acquire good S/N data by DAS fibers on the wells.
For the evaluation of the survey, we firstly studied the behavior of injected CO2 in the reservoir. Using the log data at the injection well, we constructed an axisymmetric petrophysical model. Two-phase flow simulation was carried out using TOUGH2. The simulation results indicated that, 1) radius of CO2 became larger at high permeability layer, 2) CO2 was injected from the upper part of the perforation intervals, and 3) CO2 plume could be migrated from the perforation intervals up to the top of the reservoir. Secondly, we calculated wave form from the SOVs to confirm the effect of CO2 in the reservoir. The simulated results indicated that, a) the P-wave was delayed a few msec at the near offset survey layout, and b) the effect of the CO2 plume could be detectable even at the far offset layout when the CO2 plume becomes larger.
These results suggest that SOV-DAS/VSP is useful for the monitoring of geological CO2 storage. The simulated results also provide us information for the cost-effective monitoring.