Hydrocarbon potential of the Sargelu Formation,North Iraq

Microscopic and chemical analysis of 85 rock samples from exploratory wells and outcrops in northern Iraq indicate that limestone, black shale and marl within the Middle Jurassic Sargelu Formation contain abundant oil-prone organic matter. For example, one 7-m (23-ft.)-thick section averages 442 mg?HC/g S2 and 439 °C Tmax (Rock-Eval pyrolysis analyses) and 16 wt.% TOC. The organic matter, comprised principally of brazinophyte algae, dinoflagellate cysts, spores, pollen, foraminiferal test linings and phytoclasts, was deposited in a distal, suboxic to anoxic basin and can be correlated with kerogens classified as type A and type B or, alternatively, as type II. The level of thermal maturity is within the oil window with TAI?=?3^? to 3⁺, based on microspore colour of light yellowish brown to brown. Accordingly, good hydrocarbon generation potential is predicted for this formation. Terpane and sterane biomarker distributions, as well as stable isotope values, were determined for oils and potential source rock extracts to determine valid oil-to-source rock correlations. Two subfamily carbonate oil types—one of Middle Jurassic age (Sargelu) carbonate rock and the other of Upper Jurassic/Cretaceous age—as well as a different oil family related to Triassic marls, were identified based on multivariate statistical analysis (HCA and PCA). Middle Jurassic subfamily A oils from Demir Dagh oil field correlate well with rich, marginally mature, Sargelu source rocks in well MK-2 near the city of Baiji. In contrast, subfamily B oils have a greater proportion of R₂₈ steranes, indicating they were generated from Upper Jurassic/Lower Cretaceous carbonates such as those at Gillabat oil field north of Mansuriyah Lake. Oils from Gillabat field thus indicate a lower degree of correlation with the Sargelu source rocks than do oils from Demir Dagh field. One-dimension petroleum system models of key wells were developed using IES PetroMod Software to evaluate burial-thermal history, source-rock maturity and the timing and extent of petroleum generation; interpreted well logs served as input to the models. The oil-generation potential of sulphur-rich Sargelu source rocks was simulated using closed system type II-S kerogen kinetics. Model results indicate that throughout northern Iraq, generation and expulsion of oil from the Sargelu began and ended in the late Miocene. At present, Jurassic source rocks might have generated and expelled between 70 % and 100 % of their total oil.     

Archaeological geophysics investigation of the Wright Brothers 1910 hangar site

An archaeological geophysics investigation was conducted at the site of the Wright Brothers' 1910 hangar near Dayton, Ohio. The hangar was destroyed as part of base renovation during the buildup to World War II, and its exact location is unknown. The purpose of the investigation is to confirm the exact location of the hangar and to locate any buried artifacts from the Wright Brothers occupation of the site. Ground penetrating radar (GPR), electromagnetic, and magnetic surveys were conducted over a 68 × 100 m area, approximately centered on the suspected location of the hangar. Localized anomalies as well as areal anomalies are identified in the geophysical data. Rectangular anomalous areas are identified that are generally consistent with the suspected location of the hangar. A 1924 aerial photograph showing the hangar was digitally scanned and georeferenced to the site survey area. Two of the rectangular geophysical anomalous areas are consistent with the hangar location from the aerial photograph location. A third rectangular area, defined from GPR survey data, is immediately adjacent to the aerial photograph location. It is postulated that base engineers may have bulldozed the hangar debris onto an area adjacent to its original location and either burned it there or buried it in a trench. A prioritized exploratory program is proposed for investigating the sources of the geophysical anomalies. © 1994 John Wiley & Sons, Inc.