تقييم الخصائص البتروفيزبائية لمكمني المشرف واليمامة في حقل الغراف النفطي ، جنوب العراق، بالإعتماد على تفسير المجسات البئرية

The Mishrif and Yamama Formation are the main reservoirs in the Garraf oilfield, Nasiriyah city, of the Euphrates Subzone, Mesopotamian Basin, Southern Iraq. The Garraf oilfield structural pattern corresponds with the similar anticline forming the oilfields of Rafidain and Dujaila and is parallel to the main trend of Zagros, indicating simple coaxial deformation. The petrophysical properties are evaluated using the Interactive Petrophysics V3.5 software. This comprises determining the lithology, mineralogy, and matrix for the investigated reservoirs, as estimating clay volume, total, effective, and secondary porosity, water saturation, permeability, and determining the net pay and gross thickness. The findings of this investigation indicated that the Mishrif formation is divided into two main units separated by a marl layer, with the upper unit having poor reservoir qualities and the lower unit having favorable ones. As a result, there are nine reservoir units in the lower main unit (M1, M1.2, M2, L1, L1.2, L2, L2.2, L2.3, and L2.4). The best and largest reservoir unit capacity is Unit L1.2, with exceptional petrophysical characteristics. Lower units L2.2, L2.3, and L2.4 are nearly saturated in reservoir water, with a little oil in some wells. YA, YB1, and YB2 are the three reservoir units that make up the Yamama formation. Unit YA is the best reservoir unit because of its petro physical properties.يعتبر كل من تكويني المشرف واليمامة المكمنين الرئيسيين في حقل الغراف النفطي ٠ في مدينة الناصرية ، في منطفة Euphrates Subzone ضمن حوض مابين النهرين. جنوب العراق. يتوافق النمط التركيبي لحقل الغراف النفطي مع الخط المنحني المماثل الذي يشكل حقلي نفط الرافدين والدجيلة وهو مواز لاتجاه زاغروس الرئيسي ؛ مما يشير إلى نشوه محوري بسيط. تم تفييم الخواص البتروفيزيائية باستخدام برنامج IP v3.5 . تضمن ذلك تحديد الصخارية ٠ التركيب المعدني؛ ونوع الماتركس للمكامن التي تم فحصها . وكذلك تقدير حجم الطين ٠ والمسامية الكلية والفعالة والثانوية ٠ وتشبع المياه ، والنفاذية ، وتحديد انطقة العطاء والسمك الكلي للمكمن. أشارت نتائج هذا البحث إلى أن تكوين المشرف ينقسم إلى وحدتين رئيسيتين تفصل بينهما طبقة المارل ٠ حيث نتميز الوحدة العلوية بخصائص مكمنية رديئة؛ اما الوحدة السفلية لها خصائص جيدة. نتيجة لذلك ٠ توجد تسع وحدات مكمنية ثانوية في الوحدة الرئيسية السفلية وهي (M1, M1.2, M2, L1, L1.2, L2, L2.2, L2.3, و L2.4). أفضل وأكبر سعة لوحدة الخزان هي الوحدة L1.2 والتي نتميز بخصائص بتروفيزيائية استثنائية. الوحدات السفلية و L2.2 و L2.3 و L2.4 مشبعة تقريبا بالمياه المكمنية» مع وجود كمية قليلة من النفط في بعض الآبار في حقل الغراف. YA وYB1 وYB2 هي الوحدات المكمنية الثلاثة التي تشكل تكوين اليمامة. وحدة YA هي أفضل وحدة مكامنية لما لها من خصائص بتروفيزبائية. تعتبر الصفات البتروفيزبائية للوحدتين YB1 وYB2 فقيرة وتحتوي على كمية كبيرة من المياه المكمنية

Oil-polluted groundwater in central and west Iraq as indicator of potential new hydrocarbon plays

The old land of Iraq is characterized by the presence of many oil seepages that date back to the Babylonian time. During the last few years, the country has witnessed an accelerating pattern of earthquakes that may have activated some of the major old faults and released entrapped hydrocarbons that eventually mixed with groundwater. The recent phenomenon of mixing hydrocarbons with this water has resulted in significant economic losses. Many geochemical analyses were conducted for four samples of oil contaminated with groundwater in the Karbala and Najaf regions and compared them with five samples of seep oil in the Ramadi region and one sample of bitumen extracted from the Lower Fars (Fatha) formation of Kifl-1 oil well, to find out the origin of these oils and to identify potential reservoirs that could hold important undiscovered oil reserves. Results indicate that the groundwater oils were highly mature and originated from Lower Cretaceous carbonate sources deposited under upwelling deep water, anoxic conditions. This is roughly corresponding to the bitumen extract sample of the Lower Fars Formation taken from the Kifl-1 oil well, confirming that these oils belong to the reservoir units in this formation and may therefore contain economically amounts of oil

Evaluation of the source rock potential of the Unyazah Formation (late Carboniferous-Early Permian) in Dukhan Field, Qatar

Twenty samples were collected from the Unayzah Formation in three wells from Dukhan Field, Qatar. Many samples were of poor quality due to the low TOC content containing gas prone-kerogen type III and IV. The Rock-Eval maturity parameters indicate that many samples were immature, while the mature samples generated dry gas. The C15+ extracts GC suggests a marine input, while they have kerogen type III and IV which are usually derived from terrestrial input. This may be due to the abundance of G. Prisca which was probably recycled from older sediments. The organic matter may also have been subjected to oxidation, leaching, biodegradation or recycling due to the changing nature of the depositional environment that ranged from braided river system to marine settings

Contribution of the Zubair source rocks to the generation and expulsion of oil to the reservoirs of the Mesopotamian Basin, Southern Iraq

The huge quantities of oil and gas reserved in the fields of southern Iraq must be matched by enough source rocks that can generate and expel equivalent amounts of hydrocarbons. This study is an attempt to evaluate the potential and efficiency of the Zubair Formation strata as potential source rocks that contributed to the hydrocarbon budget. A Multiproxy investigation including TOC, pyrolysis, palynofacies, carbon isotope and biomarker analysis were used to investigate such possibility. Results indicate that Zubair rocks were ranging from poor to excellent source rocks, early to moderate maturity, and generated and expelled much hydrocarbons to the Cretaceous reservoirs of the Basin

Source rock evaluation and petroleum generation of the Lower Cretaceous Yamama Formation: Its ability to contribute to generating and expelling petroleum to cretaceous reservoirs of the Mesopotamian Basin, Iraq

The Yamama Formation is an important reservoir as well as a good source rocks in many of the oilfields of the southern Mesopotamian Basin, Iraq. The formation represents a regressive cycle deposited in a shallow carbonate ramp that was under clastic influence from the nearby land. This setting is a determining factor in the organic matter content. Geochemical pyrolysis, palynofacies, biomarkers, and carbon isotope analyses were conducted on 152 samples from 27 oil wells. The formation represents a regressive cycle deposited in a shallow carbonate ramp that was under clastic influence from the nearby land. Based on pyrolysis analyses, the source rocks have poor to excellent hydrocarbon potential. The kerogen types of the Yamama source are varied, including II, II/III, III, and I. This is due to the varied depositional environments and related organic matter sources (continental to marine).The studied samples also showed a variety in distribution between oil-prone kerogen type II, distal suboxic–anoxic and the dysoxic–anoxic marine carbonate environments of (IX) and (VIII) zones of Tyson Ternary, which reflect the wide variations in the sediment depositional paleo-environments. The difference in the variations of normal alkanes of light alkanes in the range of n-C13 to n-C19 of the gas chromatography analyses, as well as the verities of the biomarker ratio of the tricyclic terpanes, hopane, and homohopane, indicate differences in the depositional setting. Similarly, the carbon stable isotope compositions of 13C (‰) saturated and 13C (‰) aromatic hydrocarbons, as well as the canonical variable value for Yamama source rock extracts, correspond to a variety of organic matter sources, ranging from open marine to terrestrial with plants.The Tmax values for most Yamama source samples range from 430 °C to 451 °C, the C27 Ts/Tm, C29 sterane 20S/(20 S + 20 R) and ββ/(ββ+αα) stereoisomer, and triaromatic steroids 3 [TAS3]) ratios, indicating that the studied samples are in the range “immature to oil window”, and that Tmax of 430–450 °C corresponds to an early to peak oil window stage. The Yamama source intervals entered the early oil window in the Late Cretaceous ranging from 80 to 62 Ma and completed oil generation in the early Eocene to Late Miocene approximately 80 to 62 Ma, according to 1D-Burial, thermal history modeling, and the timing of oil generation of selected wells covering the studied area (58–7 Ma). This confirms that these source intervals have completed petroleum generation and have contributed significantly to the supplies of crude oil and gas to surrounding reservoirs