Application of Marine Magnetic and Gravity Data in Mapping Basement and Sedimentary Horizons in the Rovuma Basin, Mozambique

Kivior, Irena¹; Chandola, Sandeep K.²; Lee, Poh Kin²; Zohdi, Siti²; Markham, Stephen¹; Damte, Shiferaw¹
¹Archimedes Consulting, Adelaide, SA, Australia.
²PETRONAS Carigali, Kuala Lumpur, Malaysia

A study of potential field data covering the offshore Rovuma Basin in Mozambique, East Africa, was conducted to map the crystalline basement and two intra-sedimentary horizons of Cretaceous and Jurassic age, as well as to determine the major fault structures within the basement. The magnetic and gravity data were acquired at the same time as marine 2D seismic.

The horizon mapping was undertaken using the Energy Spectral Analysis method in two stages; (1) The Multi-Window Test (MWT) spectral technique was applied to gridded magnetic and gravity data to identify the horizons. (2) The ESA-Moving Window (ESA-MW) technique was used to conduct detailed mapping of basement and the two sedimentary horizons that were identified. These two steps of analysis were repeated for each horizon that was interpreted.

MWT was conducted at stations located on a regular mesh, in order to detect depth plateaus which correspond to different magnetic or density interfaces. These depth plateaus were related to the following horizons, Basement, Jurassic and Cretaceous.

In the first stage, depth plateaus were detected and approximate, average depths from plateaus were used to create a skeleton map for the horizons.

In the next stage, the optimal window size was determined from the depth plateaus and used to conduct detailed horizon mapping (ESA-MW).

AAPG Search and Discovery Article #90155©2012 AAPG International Conference & Exhibition, Singapore, 16-19 September 2012