Facies Analysis and Paleoenvironmental Assessment of the Upper Campanian Hartha Formation in Y and J Fields Northwestern Zagros Basin, Iraq

The Upper Campanian Hartha Formation represents potential Cretaceous hydrocarbon-bearing reservoir rocks across the Y and J oilfields northwestern Zagros Basin, northern Iraq. The study objective is depositional environment which affects reservoir properties by tool, lithofacies, core, thin section, and logs, using petrel (V.2016) and strat software, facies distribution, grains, and diagenetic processes control and enhance reservoir properties which can plan platform production and minimize risks in choosing production wells location at two fields scale The current study is concerned with lithofacies and microfacies of the Hartha Formation within two fields in northern Iraq. Several subsurface well-log data, core, and cutting samples have been used in order to prepare thin sections that were subjected to sedimentological (lithofacies, and grain-size) examination. The petrography investigation revealed five rock-units including Hr. 1, 2, 3, 4, and 5, the thickness of 89 m in the Y-A field and increasing to up to 140 m in the J-B field might be due to erosion or tectonic uplift of the topography in Y subbasin. Which is locally sub-basin within study fields western banks of Tigris river as gentle slope ramp depositional condition with Spectrum microfacies from lime-mudstone to packstone texture with rudest and benthic debris enhances by diagenesis, dolomitization, dissolution moldic porosity, fracture; dolostone is more effective in the upper section of the formation in A than B Wells. Many factors, such as cementation, compaction, and pore-filling autogenic minerals, decrease reservoir quality, and their effects are similar in wells A and B.

Assessing Thermal Maturity through a Multi-Proxy Approach: A Case Study from the Permian Faraghan Formation (Zagros Basin, Southwest Iran)

This study focuses on the thermal maturity of Permian deposits from the Zagros Basin, Southwest Iran, employing both optical methods (Thermal Alteration Index, Palynomorph Darkness Index, Vitrinite Reflectance, UV Fluorescence) and geochemical analyses of organic matter (Rock Eval Pyrolysis and MicroRaman spectroscopy) applied to the Faraghan Formation along two investigated Darreh Yas and Kuh e Faraghan surface sections. Furthermore, an integrated palynofacies and lithofacies analysis was carried out in order to integrate the few studies on the depositional environment. The Faraghan Formation, which is widely distributed in the Zagros area, generally consists of shale intercalated with sandstones and pebble conglomerates in the lower part, followed by a succession of sandstone, siltstone and shaly intercalations and with carbonate levels at the top. The integrated palynofacies and lithofacies data confirm a coastal depositional setting evolving upwards to a shallow marine carbonate environment upwards. Rock Eval Pyrolysis and Vitrinite Reflectance analysis showed that the organic matter from samples of the Darreh Yas and Kuh e Faraghan sections fall in the mature to postmature range with respect to the oil to gas generation window, restricting the thermal maturity range proposed by previous authors. Similar results were obtained with MicroRaman spectroscopy and optical analysis such as Thermal Alteration Index and UV Fluorescence. Palynomorph Darkness Index values were compared with Rock Eval Pyrolysis and vitrinite reflectance values and discussed for the first time in the late stage of oil generation.