7 Periodical meeting CO2Monitor. Synthetic seismograms from the Sleipner injection site

Transcription

1 7 Periodical meeting CO2Monitor Synthetic seismograms from the Sleipner injection site Davide Gei, Stefano Picotti, Jose Carcione

2 Objective Modelling of the Sleipner overburden to study the sensitivity of the seismic method to leackage detection Picotti S., Gei G., Carcione J.M., 2013: Leackage detection with seismic methods at the Sleipner field: a synthetic study. In progress Petrophysical model Saturation model (leakages) Seismic modelling Sleipner injection site (North Sea) The Sleipner storage site is located in the Norwegian sector of the North Sea. This is the first commercial scale CCS project, which began in 1996 with the injection of the CO2 separated from the extracted natural gas into a deep saline aquifer contained in the Utsira Sand formation, at approximately 1 km depth below the sea bottom. Since 1996 about 1 Mt CO2 per year has been injected.

3 Utsira Formation Seismic section Overburden Main Characteristics Thickness: m Average Depth: 950 m Geology: highly permeable unconsolidated sand with mudstone intra-layers 1 meter thick. Average permeability: 3Darcy Average porosity: 37% T=29 degc; P=80bars; 3% CH4 saturation (the CO2 is almost pure)

4 Overburden (geological petrophysical model)

5 Overburden (geological petrophysical model) Sea water Gamma Ray (C2H) Gamma Ray (15/9-13) Overburden Sand lens Caprock 4 5 Reservoir (Utsira) Formation below Utsira

6 Results of the Oscillatory tests and Zener best fits These fits correspond to the leakages in the sand lens The fits are good in the frequency band of interest: 0-70Hz

7 Overburden Sea water Overburden Sand lens Caprock Reservoir (Utsira) Formation below Utsira 7

8 Overburden Geological model Previous model Sea water Overburden Sand lens Caprock Reservoir (Utsira) Formation below Utsira

9 Overburden (Pre injection) Real seismic section Synthetic seismic section Planewave simulation

10 Post-injection Synthetic seismic section (planewave) Pre-injection Synthetic seismic section (planewave) Post-injection

11 Leakages Geological model leakage 1 Geological model leakage 2

12 Post-injection + leakages Synthetic seismic section (planewave) Leakage1 (1%) Synthetic seismic section (planewave) Leakage2 (1%)

13 Post-injection + leakages Synthetic seismic section (planewave) Leakage1 (3%) Synthetic seismic section (planewave) Leakage2 (3%)

14 Post-injection + leakages Synthetic seismic section (planewave) Leakage1 (5%) Synthetic seismic section (planewave) Leakage2 (5%)

15 Post-injection + leakages Synthetic seismic section (planewave) Leakage1 (10%) Synthetic seismic section (planewave) Leakage2 (10%)

16 Shot simulations For each scenario: Baseline (no CO2) Post-injection (CO2 in the reservoir) Leakage 1 (1%, 3%, 5%, 10% CO2) Leackage 2 (1%, 3%, 5%, 10% CO2) we need to compute shot datasets (92 point sources per scenario). The total number of shots is 920. At the moment the shots of 3% CO2 are under computing while the other dataset are ready to be processed.

17 Geological model leakage 1 No leakage

18 Geological model leakage 1 1% CO2

19 Geological model leakage 1 5% CO2

20 Geological model leakage 1 10% CO2

21 Leakage Imaging We perform pre-stack depth migration of the simulated seismic surveys, in order to image the leakages and to evaluate the RMS signatures and the corresponding detection thresholds. work in progress...