Changes

In [[:file:applying-gravity-in-petroleum-exploration_fig15-8.png|Figure 2]], the upper panel shows a map of a land gravity survey taken near Khartoum, Sudan. The stippled contours are gravity values of -50 mGal and lower. The exploration objective was to identify new Mesozoic subbasins along the Central African Rift system. These subbasins cannot be seen at the surface because they are covered by a thin veneer of alluvium, sand, and river deposits. However, the subbasins, because they are lower density than cratonic basement, can be identified in the gravity data as large gravity minima, shown in the stipled pattern.

In [[:file:applying-gravity-in-petroleum-exploration_fig15-8.png|Figure 2]], the upper panel shows a map of a land gravity survey taken near Khartoum, Sudan. The stippled contours are gravity values of -50 mGal and lower. The exploration objective was to identify new Mesozoic subbasins along the Central African Rift system. These subbasins cannot be seen at the surface because they are covered by a thin veneer of alluvium, sand, and river deposits. However, the subbasins, because they are lower density than cratonic basement, can be identified in the gravity data as large gravity minima, shown in the stipled pattern.

[[file:applying-gravity-in-petroleum-exploration_fig15-9.png|left|thumb|{{figure number|3}}Modified from Grow et al.<ref name=Growetal_1988>Grow, J. A., K. D. Klitgord, and J. S. Schlee, 1988, Structure and evolution of Baltimore Canyon Trough, ''in'' R. E. Sheridan and J. A. Grow, eds., The geology of North America, v. I-2: Geological society of America, p. 269-290.</ref> and Sheridan et al.<ref name=ch15r11>Sheridan, R., E., Grow, J., A., Klitgord, K., D., 1988, Geophysical data, in Sheridan, R., E., Grow, J., A., eds., The Geology of North America, v. I-2: Geological Society of America, p. 177–196.</ref> Gravity model by [[D.R. Hutchinson and J.A. Grow (1980)]],{{citation needed}} courtesy USGS.]]

[[file:applying-gravity-in-petroleum-exploration_fig15-9.png|left|thumb|{{figure number|3}}Modified from Grow et al.<ref name=Growetal_1988>Grow, J. A., K. D. Klitgord, and J. S. Schlee, 1988, Structure and evolution of Baltimore Canyon Trough, ''in'' R. E. Sheridan and J. A. Grow, eds., The geology of North America, v. I-2: Geological society of America, p. 269-290.</ref> and Sheridan et al.<ref name=ch15r11>Sheridan, R., E., Grow, J., A., Klitgord, K., D., 1988, Geophysical data, in Sheridan, R., E., Grow, J., A., eds., The Geology of North America, v. I-2: Geological Society of America, p. 177–196.</ref> Gravity model by D.R. Hutchinson and J.A. Grow (1980),{{citation needed}} courtesy USGS.]]

Nearby in a similar geologic setting, Chevron made a series of discoveries in the Muglad area using gravity as a primary exploration tool.<ref name=ch15r4>Giedt, N., R., 1990, [http://archives.datapages.com/data/specpubs/fieldst3/data/a017/a017/0001/0150/0177.htm Unity field--Sudan Muglad rift basin, Upper Nile province], in Beaumont, E., A., Foster, N., H., eds., Structural Traps III: Tectonic Fold and Fault Traps: AAPG Treatise of Petroleum Geology Atlas of Oil and Gas Field 3, p. 177–197.</ref> The gravity lows in this map indicate hitherto undiscovered subbasins, identified along gravity profile A–A′ in the bottom panel.

Nearby in a similar geologic setting, Chevron made a series of discoveries in the Muglad area using gravity as a primary exploration tool.<ref name=ch15r4>Giedt, N., R., 1990, [http://archives.datapages.com/data/specpubs/fieldst3/data/a017/a017/0001/0150/0177.htm Unity field--Sudan Muglad rift basin, Upper Nile province], in Beaumont, E., A., Foster, N., H., eds., Structural Traps III: Tectonic Fold and Fault Traps: AAPG Treatise of Petroleum Geology Atlas of Oil and Gas Field 3, p. 177–197.</ref> The gravity lows in this map indicate hitherto undiscovered subbasins, identified along gravity profile A–A′ in the bottom panel.