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AAPG GEO 2010 Middle East
Geoscience Conference & Exhibition
Innovative Geoscience Solutions – Meeting Hydrocarbon Demand in Changing Times
March 7-10, 2010 – Manama, Bahrain

Devonian Spore Assemblages from the Jubah, Jauf and Tawil Formations, South of Ghawar Field, Eastern Saudi Arabia

Abdulla M. Al-Ghazi1; Mansour Al-Ruwaili1; Merrell Miller1

(1) Exploration Tech Services, Saudi Aramco, Dhahran, Saudi Arabia.

An exploration well located south of Ghawar Field contains one of the most complete early upper and Lower Devonian successions in the area. The palynological control from this well provides a Devonian reference section for this area that will help refine regional correlations. An apparently complete succession of operational palynological zones (Al-Hajri et al., GeoArabia, 1999) from the Frasnian-Givetian/upper Eifelian D2 Palynozone to the Lochkovian D4B Palynozone was identified in this well. The upper part of the Jubah Formation, typically represented by the D0 to D1 Palynozones, was truncated by the Hercynian erosion. D2 Palynozone was recognized from 15,000-15,350 ft and is indicative of the presence of ?Frasnian-late Eifelian age sediments. This interval is dominated by terrestrial palynofloras. D3A Palynozone spans the Jubah/Jauf formational boundary and occurs from the 15,350-15,690 ft interval. D3B Palynosubzone, which caps the Jauf reservoir, occurs in the 15,690/15,710 ft sample (D3A and D3B are late Emsian in age). The D3B event is the only acritarch (leiosphere) dominated palynological event recognized in the succession. The D3/D4-D4A palynozones of Emsian-Pragian age are present in the 15,710-15,890 ft interval and span the Jauf/Tawil formational boundary. Lochkovian D4B was recognized from 15,890-16,090 ft and suggests the presence of the Tawil Formation. The section below the D3B Palynozone is dominated by terrestrial palynomorph assemblages.