The Hydrocarbon Geology of Southern Offshore Malta and Surrounding Regions

Abstract

Studies of more than 10,000 km of geophysical data from an area situated 45 km south of Malta, supported by stratigraphic projections from wells in offshore Sicily, Tunisia and Libya, indicate facies different from the continuous carbonate sequence encountered in wells on the Malta Platform. Geologic structures in the study area range from a broad anticlinal high to complex horst‐and‐graben systems that are mostly of post‐Miocene age. One graben is believed to be an Early Mesozoic rift associated with break‐up of Gondwana, and may contain deep‐water Triassic‐Jurassic strata similar to those of the Ragusa Basin in SE Sicily. Triassic and Jurassic shallow‐water carbonates were penetrated in wells to the north of the study area. These wells also encountered Upper Jurassic — Cretaceous carbonates, which consist mostly of restricted‐shelf dolomites; pelagic limestones are present at one well located in a re‐entrant of the Malta Platform. During Cretaceous time, part of the study area was transitional between platform and basin settings, and the presence of deeper‐water strata, similar to those which provide proved or potential source rocks and seals in Tunisia, is predicted. Shelf‐edge carbonates can provide good reservoirs; rudistid reefs probably developed on bathymetric highs. Based on the temperature gradient in a well near the study area, most of the Cretaceous section, at least in the Mesozoic graben, is capable of peak oil generation. Cretaceous source rocks reached maturity in the SE part of the study area during Miocene times, and elsewhere between the Pliocene and the present day. Restored seismic sections indicate that faults were active and structures developed by the beginning of Tertiary time. Several trap types are present, and the area has the potential to contain major hydrocarbon reserves.

Seismic stratigraphy, tectonics and depositional history in the Halk el Menzel region, NE Tunisia

“…Compilation of various data (Bishop, 1988;Burollet, 1991;Bishop and Debono, 1996) outlines that the structural style of the gulf of Hammamet controlled the source and the reservoir-rock deposition, the source-rock maturation, the petroleum migration paths and the distribution of traps (Fig. 22).…”

The Role of Fluid Seepage in the Erosion of Mesozoic Carbonate Escarpments

“…There are indications for the occurrence of evaporites in the other escarpments. Evaporites have been reported in onshore and offshore wells at depths of 1 and 5 km in the Malta Plateau (Bishop & Debono, 1996; Gatt, 2012). Extensive beds of gypsum/anhydrite‐bearing evaporite of probable Palaeogene age outcrop across the Campeche Escarpment (Hudec & Norton, 2019; Perry et al., 2012).…”

“…There are indications for the occurrence of evaporites in the other escarpments. Evaporites have been reported in onshore and offshore wells at depths of 1 and 5 km in the Malta Plateau (Bishop & Debono, 1996;Gatt, 2012). Extensive beds of gypsum/anhydrite-bearing evaporite of probable Palaeogene age outcrop across the Campeche Escarpment (Hudec & Norton, 2019;Perry et al, 2012) Canyon area was estimated based on the boundaries of submarine canyons delineated semi-automatically using morphometric attribute maps (slope gradient, slope aspect, profile curvature), flow accumulation map and water basin analysis.…”