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Accurate estimates of losses occurring during secondary petroleum migration are of vital importance for valid petroleum systems assessments. In this paper, we discuss the development of migration pathways and the corresponding hydrocarbon losses using data from laboratory experiments based on diphasic immiscible draining processes. These experiments permitted us to study the formation of migration pathways, the distribution of non‐wetting oil along these pathways, and the re‐utilization of existing pathways by later pulses of migrating oil. The configuration of a migration pathway can be characterized by a phase diagram whose coordinates are two dimensionless numbers: the capillary number and the Bond number (a measure of the buoyancy force). NMR imaging was used to measure the saturation of residual oil within the pathways. It was found that, after migration, the average residual oil saturation within a pathway was generally less than 40% at a resolution of 0.4mm. Hydrocarbon losses during migration were estimated as the product of the volumetric proportion of the migrating cluster structure, defined using this spatial resolution, multiplied by the average residual oil saturation in the pathway.

Shale oil and gas have been discovered in the lacustrine organicrich Zhangjiatan Shale of the Upper Triassic Yanchang Formation, Ordos Basin, China. Core observations indicate abundant silty laminae in the producing shales. This study documents the stratigraphic distribution of silty laminae and their relationship with interlaminated clay laminae. The type, structure, and characteristics of pores and mineral composition of silty laminae were observed and analyzed through thin section and scanning electron microscopy, X-ray diffraction, low-pressure CO 2 and N 2 adsorption, mercury porosimetry, and helium pycnometry. Results from silty laminae are compared with those of clayey laminae. The frequency and thickness of silty laminae vary over a wide range. The thickness ranges from 0.2 to 4 mm and is 1.5 mm on average; the frequency ranges from 4 to 32 laminae/m and is 23 laminae/m on average. The thickness percentage of silty laminae in the measured segments ranges from 6% to 17%. Silty laminae consist of quartz, feldspar, mixed-layer montmorillonite, and chlorite. In comparison to clayey laminae, non-clay detrital grains are larger, quartz and feldspar are more common, and clay minerals are less abundant. Pores in silty laminae are primary interparticle, dissolutional, intercrystalline, and microfracture types. Mesopores (2-50 nm in diameter) and macropores (50 nm-1 μm) are common, whereas, micropores ð<2 nmÞ are rare; the distribution of pore diameters is multimodal. However, microscopic pores with a diameter commonly smaller than 100 nm are common in

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Second sound attenuation, a distinctive dissipative hydrodynamic phenomenon in a superfluid, is crucial for understanding superfluidity and elucidating critical phenomena. Here, we report the observation of second sound attenuation in a homogeneous Fermi gas of lithium-6 atoms at unitarity by performing Bragg spectroscopy with high energy resolution in the long-wavelength limit. We successfully obtained the temperature dependence of second sound diffusivity D 2 and thermal conductivity κ. Furthermore, we observed a sudden rise—a precursor of critical divergence—in both D 2 and κ at a temperature of about 0.95 superfluid transition temperature T c . This suggests that the unitary Fermi gas has a much larger critical region than does liquid helium. Our results pave the way for determining the universal critical scaling functions near quantum criticality.

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