1. SEAM PHASE I GRAVITY
Neda Bundalo

2. SEAM PHASE I GRAVITY MODEL
DENSITY MODEL - Cell size 40x40x20 m - Density range – (2.64) g/cm3
SEAM Phase I model: density cube

3. SEAM PHASE I GRAVITY MODEL
CALCULATED GRAVITY Gravity (vertical component) Gz and six tensor components (gradients) Txx, Txy, Txz, Tyy, Tyz, Tzz, - GMSYS 3D (Geosoft) and 3MOD (LCT Fugro), - free-air and Bouguer anomalies on two calculation levels: 0 m for marine and 150 m for airborne data, - recommended data storage formats: Geosoft grid and ascii xyzg.
Vector (beige) and tensor (red)
components of gravity field;
after Murphy, 2004.

4. SEAM PHASE I GRAVITY MODEL
CALCULATED GRAVITY - with and without background density - density of 2.2 g/cm3 used as a background density (mean voxel density) - density of 2.0 g/cm3 used for Bouguer correction
Grid description and coordinate system???
SEAM Phase I model: vertical density slice

5. SEAM PHASE I GRAVITY MODEL
Free-air anomalies at sea level
background density 2.2 g/cm3
Txx
Txy
Txz
Tyy
Tyz Gz
Tzz

6. SEAM PHASE I GRAVITY MODEL
Free-air anomalies at 150 m level
background density 2.2 g/cm3
Txx
Txy
Txz
Tyy
Tyz Gz
Tzz

7. SEAM PHASE I GRAVITY MODEL
Bouguer anomalies at sea level
Bouguer correction density 2.0 g/cm3
background density 2.2 g/cm3
Txx
Txy
Txz
Tyy
Tyz Gz
Tzz

8. SEAM PHASE I GRAVITY MODEL
Bouguer anomalies at 150 m level
Bouguer correction density 2.0 g/cm3
background density 2.2 g/cm3
Txx
Txy
Txz
Tyy
Tyz Gz
Tzz

9. SEAM PHASE I GRAVITY MODEL
Free-air anomalies at sea level, background density 2.2 g/cm3 Gz
Txx
Txy
Txz
min
max
25.454
36.225
43.529
93.064
mean
6.779
2.735
0.571
2.066 sd
8.32
16.152
9.119
18.357
Tyy
Tyz
32.299
70.765
-1.158
-1.389
15.070
17.855
Tzz
-1.577
24.944

10. SEAM PHASE I GRAVITY MODEL
Free-air anomalies at 150 m level, background density 2.2 g/cm3 Gz
Txx
Txy
Txz
min
max
24.322
32.910
38.997
mean
6.802
2.679
-0.558
2.051 sd
8.026
14.840
8.403
16.857
Tyy
Tyz
30.487
59.683
-1.184
-1.324
14.043
16.605
Tzz
-1.495
22.987

11. SEAM PHASE I GRAVITY MODEL
Bouguer anomalies at sea level, Bouguer correction density 2.0, background density 2.2 g/cm3 Gz
Txx
Txy
Txz
min
64.288
-5.424
-6.459
max
84.389
16.301
4.181
21.490
mean
73.908
3.800
-0.384
1.537 sd
4.955
5.260
1.912
7.421
Tyy
Tyz
-6.272
8.808
6.386
0.655
-1.266
2.685
3.067
Tzz
8.840
-4.455
6.992

12. SEAM PHASE I GRAVITY MODEL
Bouguer anomalies at 150 m level, Bouguer correction density 2.0, background density 2.2 g/cm3 Gz
Txx
Txy
Txz
min
64.619
-5.078
-5.753
max
84.288
15.635
3.904
19.635
mean
73.974
3.750
-0.377
1.522 sd
4.898
5.453
1.829
7.223
Tyy
Tyz
-5.824
8.353
5.632
0.636
-1.245
2.570
2.918
Tzz
7.909
-4.386
6.757

13. SEAM PHASE I GRAVITY MODEL
RANGES OF GRAVITY ANOMALIES AND CORRESPONDING GRADIENTS Gz
mGal
Txx E
Txy
Txz
Tyy
Tyz
Tzz
FREE-AIR ANOMALIES AT SEA LEVEL
37.65
138.80
104.31
168.57
118.63
151.77
186.31
FREE-AIR ANOMALIES AT 150 m LEVEL
36.08
119.20
92.11
146.67
106.37
131.25
160.73
BOUGUER ANOMALIES AT SEA LEVEL
20.10
21.72
10.64
34.85
15.08
17.96
32.43
BOUGUER ANOMALIES AT 150 m SEA LEVEL
19.67
20.71
9.66
31.72
14.18
16.12
30.46

14. SEAM PHASE I GRAVITY MODEL
NEXT STEP
COMPARISON OF BASE OF SALT INVERSIONS
USING VERTICAL COMPONENT AND GRAVITY GRADIENTS
CONTRIBUTORS Dr. Neda Bundalo (Marathon Oil), Dr. Richard Day (ConocoPhillips), John Bain (Bain Geophysical Services, Inc.) THANKS TO Dr. Xiong Li, Barry Wiggins, Pat Quist (Fugro Gravity and Magnetics Services, Inc.), Dr. Stuart Hall (Department of Geosciences, University of Houston), Dr. Irina Filina (Hess)