Programed oil generation of the Zubair Formation, Southern Iraq oil fields: results from Petromod software modeling and geochemical analysis

1D petroleum system modeling was performed on wells in each of four oil fields in South Iraq, Zubair (well Zb-47), Nahr Umr (well NR-9), West Qurna (well WQ-15 and 23), and Majnoon (well Mj-8). In each of these fields, deposition of the Zubair Formation was followed by continuous burial, reaching maximum temperatures of 100°C (equivalent to 0.70%Ro) at depths of 3,344–3,750 m of well Zb-47 and 3,081.5–3,420 m of well WQ-15, 120°C (equivalent to 0.78%Ro) at depths of 3,353–3,645 m of well NR-9, and 3,391–3,691.5 m of well Mj-8. Generation of petroleum in the Zubair Formation began in the late Tertiary, 10 million years ago. At present day, modeled transformation ratios (TR) indicate that 65% TR of its generation potential has been reached in well Zb-47, 75% TR in well NR-9 and 55-85% TR in West Qurna oil field (wells WQ-15 and WQ-23) and up to 95% TR in well Mj-8, In contrast, younger source rocks are immature to early mature (<20% TR), whereas older source rocks are mature to overmature (100% TR). Comparison of these basin modeling results, in Basrah region, are performed with Kifle oil field in Hilla region of western Euphrates River whereas the Zubair Formation is immature within temperature range of 65–70°C (0.50%Ro equivalent) with up to 12% (TR?=?12%) hydrocarbon generation efficiency and hence poor generation could be assessed in this last location. The Zubair Formation was deposited in a deltaic environment and consists of interbedded shales and porous and permeable sandstones. In Basrah region, the shales have total organic carbon of 0.5–7.0 wt%, Tmax 430–470°C and hydrogen indices of up to 466 with S2?=?0.4–9.4 of kerogen type II & III and petroleum potential of 0.4–9.98 of good hydrocarbon generation, which is consistent with 55–95% hydrocarbon efficiency. These generated hydrocarbons had charged (in part) the Cretaceous and Tertiary reservoirs, especially the Zubair Formation itself, in the traps formed by Alpine collision that closed the Tethys Ocean between Arabian and Euracian Plates and developed folds in Mesopotamian Basin 15–10 million years ago. These traps are mainly stratigraphic facies of sandstones with the shale that formed during the deposition of the Zubair Formation in transgression and regression phases within the main structural folds of the Zubair, Nahr Umr, West Qurna and Majnoon Oil fields. Oil biomarkers of the Zubair Formation Reservoirs are showing source affinity with mixed oil from the Upper Jurassic and Lower Cretaceous strata, including Zubair Formation organic matters, based on presentation of GC and GC-MS results on diagrams of global petroleum systems.     

On Solving Groundwater Flow and Transport Models with Algebraic Multigrid Preconditioning

Iterative solvers preconditioned with algebraic multigrid have been devised as an optimal technology to speed up the response of large sparse linear systems. In this work, this technique was implemented in the framework of the dual delineation approach. This involves a single groundwater flow linear solution and a pure advective transport solution with different right-hand sides. The new solver was compared with other preconditioned iterative methods, the MODFLOW's GMG solver, and direct sparse solvers. Test problems include two- and three-dimensional benchmarks spanning homogeneous and highly heterogeneous and anisotropic formations. For the groundwater flow problems, using the algebraic multigrid preconditioning speeds up the numerical solution by one to two orders of magnitude. The algebraic multigrid preconditioner efficiency was preserved for the three dimensional heterogeneous and anisotropic problem unlike for the MODFLOW's GMG solver. Contrarily, a sparse direct solver was the most efficient for the pure advective transport processes such as the forward travel time simulations. Hence, the best sparse solver for the more general advection-dispersion transport equation is likely to be Péclet number dependent. When equipped with the best solvers, processing multimillion grid blocks by the dual delineation approach is a matter of seconds. This paves the way for its routine application to large geological models. The paper gives practical hints on the strategies and conditions under which algebraic multigrid preconditioning would remain competitive for the class of nonlinear and/or transient problems.     

沙枣树的出胶与环境影响因素研究

沙枣树的出胶量与多种影响因子有关。观测实验结果表明,沙枣树出胶量与自身的生理活性有关,而生理活性取决于水分条件。水分条件较好的相对湿润林带,沙枣树出胶量较高,而水分条件较差的干旱林带,沙枣树出胶量较低,不同水分条件下的出胶量火小依次为：湿润〉半湿润〉干旱条件：气温对激活和提高树木生理活性有积极作用,沙枣树的出胶量随气温升高显著增加,出胶旺盛季节通常在5～7月;沙枣树的创口类型和数量影响出胶量,出胶量有随创口数的增加而增加的趋势,但不同创口类型的数量对出胶量的影响是不同的,机械伤害和病虫害是造成沙枣树创口产生的原因之一;树龄与树木的生理活性对出胶有直接关系,树龄25年左右的成熟林出胶量最高,极显著地大于树龄17年的中龄林和41年的过熟林。过熟林遭受病虫害侵袭的程度远较中龄林大,出胶量也大于中龄林木。     

An In‐Depth Characterization of Urban Aerosols Using Electron Microscopy and Energy Dispersive X‐Ray Analysis

The physical and chemical characterization of aerosols from three large cities, Karachi and Islamabad, Pakistan, and New York City (NYC), USA, was investigated. A scanning electron microscope equipped with an energy dispersive spectrometer (EDS) was used to determine particle morphology and elemental composition of the samples. A Bruker Spirit system in combination with a Sahara detector provided both computer controlled Automated Chemical Classification (ACC) and digital mapping features for analysis purposes. The use of these two features to characterize the elemental composition, particle size, and to determine specific classes or source types is described in this paper. Filters were analyzed for the following elements; Na, Mg, Al, Si, P, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, As, Se, Br, Sr, Y, Zr, Mo, Pd, Ag, Cd, In, Sn, Sb, Ba, La, Au, Hg, Tl, Pb, and U. The EDS work was qualitative not quantitative. Seven source types (mobile, cement, soil, steel mill, fossil fuel, sea salt and biological) contributed to particulate matter in the ambient air of both cities in Pakistan, whereas there were eight source types (diesel, road dust, automobile, iron, residual fuel oil, sea salt, ammonium sulfate and ammonium nitrate) for NYC. For all three urban centers, vehicular traffic emissions were the main contributor to particle number. Diesel emissions from trucks and buses were relatively more prominent in NYC aerosols, while gasoline emission from automotive exhaust was dominant in the two cities of Pakistan. The cement/limestone component from local cement industries was very evident in both particle surface characteristics and number for both Karachi and Islamabad, but not in NYC air. Sea salt aerosols were seen in the two coastal cities, Karachi and NYC. It was also witnessed in Islamabad aerosols and was attributable to the mining of rock salt at the world's richest salt mine, Khewra, situated upwind from the city.     

Caractérisation géochimique des fluides associés aux minéralisations PbZn de Bou-Dahar (Maroc)

The Bou-Dahar PbZn Mississippi Valley deposits located in the eastern part of the High Atlas Range (Morocco) are hosted by a Liassic reefal complex. Fluid inclusion and ‘crush-leach’ data show that two distinct fluids were involved in the mineralisation deposition: a warmer, more saline fluid (180?°C, $>25\text{wt\%}$ NaCl equivalent) and a cooler, less saline fluid (70?°C, 16 wt% equivalent NaCl). Mixing of these two fluids resulted in the precipitation of the ore. The solute composition of the ore-forming brine suggests that the MVT mineralising fluids were probably a mixture of halite-dissolution fluids and evaporated seawater. To cite this article: S. Adil et al., C. R. Geoscience 336 (2004).