Time-lapse well logging to monitor injected CO 2 in an aquifer at Nagaoka

Nagaoka Project Time-lapse well logging to monitor injected CO 2 in an aquifer at Nagaoka Daiji Tanase 1), Jiro Watanabe 2), Ziqiu Xue 3), Hiroyuki Azuma 4) 1: Engineering Advancement Association of Japan (ENAA) 2: Geophysical Surveying Co., Ltd. 3: Research Institute of Innovative Technology for the Earth (RITE) 4: Oyo Corporation 3rd MEETING of the MONITORING NETWORK October 30 - November 2, 2006

Overview Chronicle of Nagaoka Project FY2000 : Site Selection South Nagaoka Gas Field Drilling of Wells, Well logging and Test of Core Sample FY 2000 : Injection well (IW-1) drilled FY 2001 : Two observation wells (OB-2, OB-3) drilled FY 2002 : One observation well (OB-4) drilled FY 2002 2003 : Construction of the Facilities FY 2003 2004 : Injection of CO 2 10,405t FY 2002 present :Monitoring of CO 2 FY 2000 present : Simulation Study FY 2000 2002 : Simulation prior to the injection start Optimum arrangement of CO 2 monitoring etc. FY 2003 - present : History matching simulation after the injection start Long-term CO 2 behavior anticipation FY 2007 Blockage of Wells

Overview Test Site Test Site

Overview Test Site Test Site 0 1km

Overview Test Site Test Site

Overview Test Site Observation wells Liquified CO 2 Vessel Pumps & Heater Injection well Pipe Line 0 100m

Overview Well Configuration Injection well : IW-1 Observation well :OB-2, OB-3, OB-4 IW-1 OB-2 OB-3 OB-4 Cap rock IW-1 Reservoir

Main Features of CO 2 Injection Reservoir: Aquifer of 1,100m deep Duration of Injection: About 18 months Injection started on 7 July 2003, ended 11 January 2005 Total Amount of CO2 : 10,405 t Injection Rate: 20-40t /day CO 2 Phase: kept to be Supercritical Phase (at Well Bottom) Injection Pressure Well Head 6.6-7.4 MPa Well Bottom 11.9-12.6 MPa Temperature of CO 2 Overview Well Head 32.0-35.5 Well Bottom 45.0-48.6 CO 2 Phase: kept to be Supercritical Phase (at Well Bottom)

Overview Sketch of Injection

Overview Flow of Investigation & Monitoring Earthquake Spinner survey (FY2004) Fluid sampling (FY2005)

Monitoring Pressure & Temperature Measurement Continuously at well bottom and well head) Time-lapse Logging (Baseline + 22 times during injection +8 times after the end of injection ) Induction Log Neutron Log Acoustic Log Time-lapse Cross-well Seismic Tomography Six times : Before the injection After the injection Seismicity observation (continuously) Micro earthquake Fluid Sampling 11 months after the end of injection

Monitoring Well Configuration Arrangement of Wells at Reservoir Level Logging Bottom-hole pressure and temperature OB-4 OB-3 Logging 60m Formation dip: 15 IW-1(Injection well) 120m 40m Cross-well Seismic Tomography Bottom-hole pressure and temperature OB-2 Logging Fluid sampling Injection well : Perforated at Zone-2 (12m) Observation wells : FRP Casing at reservoir interval

Monitoring Progress of Injection and Monitoring Fluid sampling Dec., 2005 11 months after Earthquake Oct.23, 2004 Seismic Tomography MS3 : 8900t Seismic Tomography MS4 : 10405t Seismic Tomography MS5 Oct. 2005 9 months afer Seismic Tomography MS2 : 6200t Start : July 7, 2003 Seismic Tomography MS1 : 3200t Spinner Test April, 2004 End : Jan. 11, 2005 Seismic Tomography BL1 FY2003 FY2004 FY2005 Pressure & Temperature Measurement Seismicity Observation

Monitoring Pressure Measurement Earthquake Oct.23, 2004

Monitoring Time-lapse Crosswell Seismic Tomography OB-3 IW-2 OB-2 3,200 t Max 3.0% OB-3 IW-2 OB-2 10,400 t Max 3.5% MS1/BLS MS4/BLS

Time-lapse Well Logging Improved Understanding of the CO 2 Movement in the Porous Sandstone Reservoir Breakthrough time (the arrival of injected CO2) Liquified CO2 Vessel OB-2 OB-4 OB-3 IW-1 Logging Unit

Time-lapse Well Logging Breakthrough Breakthrough

Time-Lapse Well Logging CO 2 Breakthrough at OB-2 16th logging on May 12 (4,300t-CO 2 ) No Change 17th logging on June 14 OB-4 (5,400t-CO 2 ) P-wave velocity : decrease 0.33 km/sec, 13% Neutron porosiry : decrease 6 % 60m 13th logging on Feb. 12 (3,500t-CO 2 ) No Change 14th logging on Mar. 10 (4,000t-CO 2 ) P-wave velocity : decrease 0.71 km/sec, 28% Resistivity : increase 0.54Ω m Neutron porosiry : decrease 10 % 120m 40m OB-2 OB-3 No Change IW-1(Injection well) Induction Log Neutron Log Acoustic Log Gamma Ray Log

Time-Lapse Well Logging CO 2 Breakthrough at OB-2 Vp Neutron Porosity Resistivity Vp : 2.55 1.84 km/sec 0.71km/sec, 28% φn : 0.24 0.14 0.10, 42% R : 5.02 5.56 Ω m 0.54Ω m, 11% Feb. 12. 2004 Mar. 10. 2004

Time-Lapse Well Logging Well Logging Result :OB-2 2 (Vp( Vp) End of Injection

Time-Lapse Well Logging Well Logging Result :OB-22 (resistivity( resistivity) End of Injection

Time-Lapse Well Logging Well Logging Result : OB-2 (Neutron porosity) End of Injection

Time-Lapse Well Logging Well Logging Result :OB-4 4 (Vp( Vp) End of Injection

Time-Lapse Well Logging Well Logging Result :OB-4 (Neutron porosity) End of Injection

Time-Lapse Well Logging Change of values (OB-2) Vp +0.4 Neutron porosity 0-0.4 Resistivity CO2 injection

Overview Time-Lapse Well Logging Spinner (flow meter) Test PLT Tool Packer 1081.84m Pump out plug Bottom 1085.72m Top 1093m Bottom 1105m Bridge Plug 1113m

Time-Lapse Well Logging Flow Meter Injection Rate and Logging Result Change of Neutron Porosity (ΔΦn) and FFV at OB-2 Injection Rate (t/day) at IW-1 1090 0 5 10 1095 1100 1105 1110

Time-Lapse Well Logging Change of Neutron porosity and NMR Result (OB-2)

Time-Lapse Well Logging P-Wave Velocity Response (OB-2 : 1,116m)

Time-Lapse Well Logging Change of Resistivity at OB-2 and Sampling Points 1108.6m 1.6 0.8 0.0 (Ω m) Zone-2 1114.0m -0.8 1118.0m

Time-Lapse Well Logging History of CO 2 Saturation at OB-2 and Sampling Points 1108.6m Zone-2 1114.0m 1118.0m

Time-Lapse Well Logging Conclusion CO 2 Breakthrough Responses in the well logging results due to CO 2 breakthrough at two observation wells Detectivity of CO 2 leakage Observation after Breakthrough Long-term behavior of CO 2 learned from time-lapse well logging. CO 2 saturation

Future Study Plan Additional data acquisition: Follow-up monitoring (BHP measurement, time-lapse logging, and crosswell seismic tomography) will be continued till 2007. Fluid sampling by CHDT at the injection well IW-1. Logging at the injection well IW-1 (RST or NL). Injecting water into the injection well and run logging tool in it to measure the residual CO2 saturation in an aquifer. Interpretation of time-lapse 3D seismic data is underway. History-match simulation incorporating these additional data is expected to improve our understanding of CO 2 distribution.