Evidences of a Paleokarst Area inside the Early Cretaceous Fahliyan Formation in an Oil Field in the Persian Gulf
M. Goodarzi and M. Jamalian
Event name: 79th EAGE Conference and Exhibition 2017
Session: Carbonate and Evaporite Environments, Stratigraphy and More
Publication date: 12 June 2017
Info: Extended abstract, PDF ( 1.3Mb )
Price: € 20
The Early Cretaceous Fahliyan Formation was subject to a study in a heavy oil reservoir in the Persian Gulf. 3D Seismic inversion, porosity and permeability models, CCAL data, core description and petrographic study, assisted with cyclostratigraphy indicated a karstic area (paleokarst) in the upper parts of Lower Fahliyan Member. The paleokarst was detected using seismic acoustic impedance as a circular shaped area on the crestal part of the structure in the upper parts of Lower Fahliyan Member. Macroscopic core description and petrography observations showed enlarged interparticle porosity and high effect of dissolution in shoal facies of the Lower Fahliyan with grainstone texture. CCAL data indicate very good reservoir quality for this facies. Moreover, low recovery factor of the cores from this interval (less than 40%) could be a sign of karstified carbonates. Cyclostratigraphy analysis showed a major C‐shape with a PBS at top of the Lower Fahliyan Member. Paleokarst features were observed on the facies belonging to shoal, channel and tidal flat facies belts. In the Upper Fahliyan Member, the P-Trend above the mentioned PBS indicates a retrogradation trend, which is mainly composed of shallow open marine facies and lagoon in some parts.