Oil field A, situated in Bohai Bay, was discovered in 1999 and has been developed as one of the most productive oil assets in China. It continues to hold significant growth potential for the future. Though the field contains a large amount of resources remaining to be developed, seismic imaging has been challenging in area 5, resulting in structural uncertainty for reservoir interpretation and well planning. In the past three decades, several 2D and 3D seismic surveys have been acquired, processed, and reprocessed in this area. However, due to the existence of complicated gas clouds, which are shallow, multilayered, and extensive, obscured sub-gas-cloud images appear in all legacy seismic results, making fault interpretation under the gas clouds almost impossible. To improve the sub-gas-cloud image and overall structural interpretability, a narrow-azimuth full-field ocean-bottom cable (OBC) acquisition was conducted in field A during 2018 and 2019, and later, a compressive seismic imaging (CSI)-based full-azimuth and large-offset OBC infill survey was acquired in area 5, covering the widest gas cloud. Through high-fidelity signal processing, full-waveform inversion (FWI)-driven velocity model building, and imaging using both Kirchhoff migration and reverse time migration (RTM), the seismic image quality beneath complicated gas clouds is improved significantly. It is the first time that sub-gas-cloud faults and the Base of Guantao event have been imaged by seismic without significant dim zones. CSI acquisition, FWI, and RTM are the key elements to resolve gas-cloud-related challenges in area 5.
The principal component analysis and cluster analysis methods were used to classify the forest site type of the souther n Xiaoxing'an mountain forests. The collected data sets are including vegetation types, topography, forest growth, soil and meteorological factors. Through principal components analysis , the slope position, slope degree, soil depth and soil type are selected as leading factors t o classify site type district. By cluster analysis, the forest sites of the southern Xiaoxing'an mountain are classified into 10 site groups and 35 site types. The site type classification results can be used to provide technical supports for the forest ma nagement of the Xiao x ing ' an mountain forests as well as the forest right system reform for Yichun Forestry Administrative Bureau. (Yao Wu , Kailun Qin, Minghua Zhang and Meng Li . Study on Forest Site Classification of Southern Xiaoxing'an Mountain in Northe ast of China . World Rural Observ 2013;5( 4 ): 2 7 - 3 2 ) . ISSN: 1944 - 6543 (Print); ISSN: 1944 - 6551 (Online). http://www.sciencepub.net/rural . 5
Abstract Oriented inclusions of clinopyroxene, orthopyroxene, sodic amphibole and rutile have been identified in garnet from the Lüliangshan garnet peridotite massif in the North Qaidam ultrahigh‐pressure metamorphic ( UHPM ) belt, northern Tibetan Plateau, NW China. Electron backscatter diffraction ( EBSD ) analyses demonstrate that nearly half of the measured intracrystalline clinopyroxene (8 out of 17) have topotactic crystallographic relationships with host garnet, that is, (100) Cpx //{112} Grt , (010) Cpx //{110} Grt and [001] Cpx //<111> Grt . One‐fifth of the oriented sodic amphibole (23 out of 110) inclusions of have topotactic crystallographic relationships with host garnet, that is, (010) Amp //{112} Grt , (100) Amp //{110} Grt and [001] Amp //<111> Grt . Over a third of rutile (36 out of 99) inclusions also show a close crystallographic orientation relationship with host garnet in that one <103> Rt and one <110> Rt parallel to two <111> Grt while the axes of [001] Rt exhibit small girdles centred the axes of <111> Grt . But, no ‘well‐fit’ crystallographic relationship was observed between orthopyroxene inclusions and host garnet. Considering a very long and complex history for the Lüliangshan garnet peridotite, we suggest that the low fit rates for these oriented minerals may result from several possible assumptions including different generations or multi‐stage formation mechanisms, heterogeneous nucleation and growth under non‐equilibrium conditions, and partial changes of initial crystallographic orientations of some inclusions. However, the residual quantitative ‘well‐fit’ crystallographic information is sufficient to indicate that the nucleation and growth of many pyroxene, amphibole and rutile are controlled by the lattice of the host garnet. The revealed close topotactic relationships accompanied by clear shape orientations provide quantitative microstructural evidence demonstrating a most likely exsolution/precipitate origin for at least some of the oriented phases of pyroxene, sodic amphibole and rutile from former majoritic garnet and support an ultra‐deep (>180 km depth) origin of the Lüliangshan garnet massif.
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