الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 32 |  |  |
| | | from | 32 | | |
Abstract
A detailed organic geochemical and palynofacies study of the Late Jurassic (Oxfordian–Kimmerdgian) Najmah, Tithonian-Berriasian Chia Gara and Valanginian-Turonian Balambo formations, northern Iraq has been carried out. This study has manifested the advantages of combining optically-oriented palynofacies and pyrolysis geochemical methods for source rock evaluation of the studied formations. Twenty-four crude oil samples from Cretaceous–Tertiary reservoirs, in addition to 81 core and cuttings samples retrieved from the Upper Jurassic–Lower Cretaceous succession in some oilfields from northern Iraq were studied by geochemical methods and carbon isotopes to understand their genetic relationships.>1-The present study provides for the first time new palynofacies data for the Najmah and Balambo formations as nothing has been published on both formations.>2- Rock-Eval pyrolysis data indicate a wide variation of source richness and quality, but all samples contain varying quantities of Type-I, Type-II (oil-prone) and Type-II/III (oil/gas-prone).>3- All of the investigated bitumens appear to be dominated by marine algal/bacterial organic matter, with a variable terrigenous influence.>4 Results indicate that the oils were derived from carbonate-rich source rocks that contain type-II or II-S kerogen.5-Maturity-related biomarkersfor nearly all oil and extract samples are close to the thermal endpoint value, thus indicating oil window maturity (especially Family-1 and 2, high API oils). However, the C29 sterane ααα20S and αββ ratios are below endpoint, indicating that maturity has not yet reached the peak oil generation.6- The inconsistency between the oils and source rock extracts suggests that the source rock samples are not representative of the effective source rocks.>7- Two main palynofacies units designated as PF-1 and PF-2. The PF-1 type is the dominant one encompassing the oldest Najmah Formation, followed upward by the Chia Gara Formation and terminated by the deposition of the Balambo Formation. This type shows that the Najmah Chia Gara and Balambo formations reflects distal-suboxic-anoxic basin. Type II>-I kerogen is postulated and is highly oil-prone, the PF-2 type is only retrieved from two samples in the Najmah Formation. This is located in the field VIII, which represents distal dysoxic-oxic shelf, classified as Type-II>>-I kerogen, which is expected to expel oil.>Key words: (not more than ten): Najmah – Chia Gara – Ceramics – Balambo – Jurassic- Oxfordian–Kimmerdgian- Tithonian-Berriasian- Valanginian-Turonian.