Combining biomarker and bulk compositional gradient analysis to assess reservoir connectivity

Author Posting. © The Author(s), 2010. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Organic Geochemistry 41 (2010): 812-821, doi:10.1016/j.orggeochem.2010.05.003.Hydraulic connectivity of petroleum reservoirs represents one of the biggest uncertainties for both oil production and petroleum system studies. Here, a geochemical analysis involving bulk and detailed measures of crude oil composition is shown to constrain connectivity more tightly than is possible with conventional methods. Three crude oils collected from different depths in a single well exhibit large gradients in viscosity, density, and asphaltene content. Crude oil samples are collected with a wireline sampling tool providing samples from well‐defined locations and relatively free of contamination by drilling fluids; the known provenance of these samples minimizes uncertainties in the subsequent analysis. The detailed chemical composition of almost the entire crude oil is determined by use of comprehensive two‐dimensional gas chromatography (GC×GC) to interrogate the nonpolar fraction and negative ion electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI FT‐ICR MS) to interrogate the polar fraction. The simultaneous presence of 25‐ norhopanes and mildly altered normal and isoprenoid alkanes is detected, suggesting that the reservoir has experienced multiple charges and contains a mixture of oils biodegraded to different extents. The gradient in asphaltene concentration is explained by an equilibrium model considering only gravitational segregation of asphaltene nanoaggregates; this grading can be responsible for the observed variation in viscosity. Combining these analyses yields a consistent picture of a connected reservoir in which the observed viscosity variation originates from gravitational segregation of asphaltene nanoaggregates in a crude oil with high asphaltene concentration resulting from multiple charges, including one charge that suffered severe biodegradation. Observation of these gradients having appropriate magnitudes suggests good reservoir connectivity with greater confidence than is possible with traditional techniques alone.The mass spectrometry work was supported by the NSF Division of Materials Research through DMR‐06‐54118, and the State of Florida

Microsoft Word - 515

ABSTRACT In order to study the effect of drought stress on morphologic traits, yield and yield components of 9 new hybrids of corn (Zea maize L.), an experiment was conducted in a Randomized Complete Block Design (RCBD) with three replications under drought stress and normal irrigation based on 80 and 50 % allowing water depletion, respectively at Khorasan-Razavi Agriculture Research Center, Mashhad, Iran on June 10, 2011. The results of analyze variance showed that under normal irrigation and drought condition, there was a significant difference (p<0.01) between the hybrids. Mean comparison of hybrids revealed that in normal irrigation H6 and in drought stress H8 hybrid had the maximum grain yield (12.85 and 6.75 ton/ha, respectively). Under normal irrigation and water shortage, plant height and kernel no/row had the highest positive phenotypic correlation with kernel yield. In drought condition, grain yield was decreased due to the reduction cumulative effects in yield components.

About the role of visual field defects in pure alexia

Pure alexia is an acquired reading disorder characterized by a disproportionate prolongation of reading time as a function of word length. Although the vast majority of cases reported in the literature show a right-sided visual defect, little is known about the contribution of this low-level visual impairment to their reading difficulties. The present study was aimed at investigating this issue by comparing eye movement patterns during text reading in six patients with pure alexia with those of six patients with hemianopic dyslexia showing similar right-sided visual field defects. We found that the role of the field defect in the reading difficulties of pure alexics was highly deficit-specific. While the amplitude of rightward saccades during text reading seems largely determined by the restricted visual field, other visuo-motor impairments-particularly the pronounced increases in fixation frequency and viewing time as a function of word length-may have little to do with their visual field defect. In addition, subtracting the lesions of the hemianopic dyslexics from those found in pure alexics revealed the largest group differences in posterior parts of the left fusiform gyrus, occipito-temporal sulcus and inferior temporal gyrus. These regions included the coordinate assigned to the centre of the visual word form area in healthy adults, which provides further evidence for a relation between pure alexia and a damaged visual word form area. Finally, we propose a list of three criteria that may improve the differential diagnosis of pure alexia and allow appropriate therapy recommendations

Integration of observational and analytical methodolgoies to characterize organic matter in early Archean rocks: distinguishing biological from abiotically synthesized carbonaceous matter structures

Transmission Electron Microscopy (TEM) was applied to observe and characterize carbonaceous materials (CM) extracted from black cherts and argillite in drill core from the Warrawoona Group of the Pilbara Craton, Western Australia. The black chert came from a 'white smoker type' seafloor deposit in the ca. 3.49 Ga Dresser Formation, whereas the black argillites were obtained from the 3.46 Ga Apex Basalt. The samples were observed and analyzed in TEM combined with electron dispersive spectral analysis (EDS), high resolution TEM (HRTEM) to determine molecular ordering, and C-isotope geochemistry. The TEM and HRTEM observations revealed significant morphological and structural differences between the carbonaceous materials of the Dresser and Apex samples enabling interpretations in terms of primary and secondary origins, as well as metamorphic history. Organic petrology using reflected light microscopy was used on whole rock-samples to observe mineral-organic matter relationship and CM structure relative to host rock texture. The results support an in situ, syn-depositional origin for the Dresser Formation CM. Reflectance % (Ro) of CM determined on polished whole rock-samples and polished resin-embedded CM-concentrates enabled the reconstruction of thermal history. Several Ro populations were identified in the Dresser Formation samples: probable microbial cells preserved in fluid inclusions within quartz crystals, thermally degraded CM originally belonging to microbial cells, CM coating mineral grains and reworked CM particles. In contrast, the Apex Basalt samples yielded-consistently very high Ro values corresponding to graphite stage organic-metamorphism. The weak optical anisotropy of the Apex graphite is inconsistent with formation during regional metamorphism. Two main graphite forms were identified, namely platy and tubular varieties. In HRTEM the tubular form showed nano-tubes and fullerenes within mono-layered spheres. Furthermore, TEM and HRTEM show that the void enclosed mono-layered carbon nano-spheres are more often detached from tubular graphite, forming clusters outside the nano-tubes. These forms are a key to the distinction between biologically and abiotically synthesized CM bodies, both by their small size, perfect outline and especially their resistance to thermal degradation. Dresser Formation samples are isotopically light in the range of-32.1‰ to-38.2‰ consistent with a biological source. Although TEM indicated four distinct types of CM, C-isotope analysis was undertaken on mixed CM concentrates. Nevertheless, the isotopically lighter samples contain a notable input from less thermally degraded low Ro material. On the other hand the isotopically heavier samples contain-predominantly thermally degraded high Ro CM. C-isotope compositions of the Apex CM are generally heavier than Dresser samples, between-22.5‰ and-28.6‰ consistent with high thermal stress. The samples show a C-isotope trend in which CM at 143 m depth is isotopically lighter, whereas above and below this level CM becomes increasingly and consistently isotopically heavier. The upper part of the section is dominated by platy graphite with rare nano-tubes. Predominantly tubular graphite and fullerenes characterize sample SAL-13 at 142 m depth coinciding with the isotopically lightest values. Below 143 m CM is less well preserved and predominantly of the fragmented platy graphite type, becoming increasingly isotopically heavier signifying close association with peridotite intrusion