Seismic 2D Reflection Processing and Interpretation of ... - Posiva

More documents

Recommendations

Info

6Figure 1. Locations of the refraction seismic survey lines (red) in Table 1.Length of each 24-channel geophone array was 90 meters (Figure 2). The geophonespacing was 5 meters but at the both ends and in the middle of an array it wassupplemented to 2,5 meters.Dynamite (35%) charges of 15-120 g were used as seismic source. The number ofshots for each array was nine, of which four were in-line offset shots 30-120 metersoutside the array and the rest at the both ends and in the middle of an array. Distancesbetween the shotpoints varied from 20 to 30 meters.Line number 342 was surveyed using one meter geophone spacing and elevenshotpoints on each 24 m long array.Recording was done using type 10B, 4,5 MHz vertical geophones with 374 Ohm reelmanufactured by Mark Product’s (Houston, USA) (Ihalainen 2003). Acquisition wascarried out with ABEM Terraloc Mk VI seismograph. Sampling interval was 25 µs.More detailed description of the field layout and equipment can be found in thereferences Ihalainen (2003).
7Figure 2. Survey array. At the line 342 geophone spacing was 1 meter and the numberof shots 11.Seismic data was recorded to 409,6 ms (Figure 3 and Figure 4). Quality of the stackeddata is quite good down to 200 ms but after that it gets noisier. Quality of the data alsovaries substantially from line to line as can be seen from Figure 3 and Figure 4. Forexample lines S33 and S34 are located over a rocky outcrop and due to that the data isquite noisy and therefore harder to process with uniform work flow settings. As can beseen in Figure 3, in good data for example first arrivals (P-wave), S-wave and airwaveare easily detected. In the case of a noisy data (Figure 4) this is a lot harder.PShot 1 Shot 2 Shot 3SShot 4AirwaveFigure 3. Example of a good data set after removing the noisy traces, shot gather.First P arrival is clear. Also S wave and airwaves are seen. First four shots from theline 30. AGC has been performed. Trace number on X-axis and two way travel time inseconds on Y-axis.
Page 1 and 2: Working Report 2006-114Seismic 2D R
Page 3 and 4: Seismic 2D Reflection Processing an
Page 5: 1TABLE OF CONTENTSABSTRACTTIIVISTEL
Page 9: 52 SOURCE DATA2.1 Surface seismic d
Page 13 and 14: 93 DATA PROCESSINGThe aim was to pe
Page 15 and 16: 11Processing was performed using fr
Page 17 and 18: 13Figure 7. Original spectrum from
Page 19 and 20: 15new datum and elevation differenc
Page 21 and 22: 1750-200 mslower cutoff frequency:
Page 23 and 24: 19Original first breaks were picked
Page 25 and 26: 21Figure 17. Shot gather from the l
Page 27 and 28: 23a)CDP position b)CDP numberFigure
Page 29 and 30: 25a) b)Figure 21. a) Final stacked
Page 31 and 32: 27Figure 23. Stacked section withou
Page 33 and 34: 294 INTERPRETATIONAfter the seismic
Page 35 and 36: 31events) indicates presence of off
Page 37 and 38: 33Table 4. Positions and dips for m
Page 39 and 40: 35In Figure 28 are shown the picked
Page 41 and 42: 37Figure 30. 3D view (from the sout
Page 43 and 44: 39Figure 32. Matching events in the
Page 45 and 46: 415 CONCLUSIONSAim of this work was
Page 47 and 48: 43REFERENCESAhokas, H. & Vaittinen,
Page 49 and 50: 45APPENDIX 1. STACKED SEISMIC SECTI
Page 51 and 52: 47Figure 3. Stacked section from th
Page 59 and 60: 55Figure 11. Stacked section from t
Page 61 and 62:
57Figure 13. Stacked section from t
Page 63 and 64:
Page 65 and 66:
Page 67 and 68:
Page 69 and 70:
Page 71 and 72:
Page 73 and 74:
Page 75 and 76:
Page 77 and 78:
Page 79 and 80:
Page 81 and 82:
Page 83 and 84:
Page 85 and 86:
Page 87 and 88:
Page 89 and 90:
Figure 41. Stacked section from the
Page 91 and 92:
Page 93 and 94:
Figure 45. Stacked section from the
Page 95 and 96:
Page 97 and 98:
show all

Seismic 2D Reflection Processing and Interpretation of ... - Posiva

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?