--> Abstract: Characterization of the Hercynian Unconformity, for Prospect Evaluation, Saudi Arabia, by Sulaiman L. Al-Sulami and Mohammed Ameen; #90105 (2010)

Datapages, Inc.Print this page

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

Characterization of the Hercynian Unconformity, for Prospect Evaluation, Saudi Arabia

Sulaiman L. Al-Sulami1; Mohammed Ameen1

(1) Saudi Aramco, Dhahran, Saudi Arabia.

The Hercynian unconformity in the Arabian plate (Late Devonian to Early Carboniferous) impacts the hydrocarbon resources and therefore is an essential aspect of prospect evaluation and field development. We conducted a regional characterization of the unconformity using an integrated, multidisciplinary method, including borehole images, dipmeters, open-hole logs, cores, seismic data, VSP, inorganic geochemistry and palynology. The study included 13 key wells with over 14,000 ft of borehole images (across the unconformity) and several hundred Km of seismic sections across key prospects and traps.

The study shows the unconformity is manifested in distinct modes in terms of:

  1. Unconformity facies: including conglomerate/breccia, paleosols, and disturbed zones due to soft sediments deformation.
  2. Angular discordance: including change in dip azimuth, or dip angle, or both.
  3. Occurrence of tectonic faults.

The above aspects of unconformity modes offer different hydrocarbon configurations. These include positive configurations that facilitate a sealing effect, potential reservoirs, or potential paths for hydrocarbon migration. In addition they include negative configurations that result in losses of potential resources, through weathering and erosion, of potential source rocks and reservoir rocks. Case studies of these configurations from mainland Saudi Arabia are presented and discussed in this paper.