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Tong S.,Beijing Jiaotong University | Tong S.,Petrochina | Li B.,Shenhua Geological Exploration Co. | Luo Q.,China University of Petroleum - Beijing | Wang H.,Ninth Oil Production Plant of Daqing Oilfield Company
Oil and Gas Geology

Based on characteristics and spatial distribution patterns of single-well sedimentary microfacies, gross-to-net ratio and thickness of single sandstone layer of the Putaohua reservoir in south Gulong sag of Songliao Basin, we studied the spatial distribution pattern of sedimentary microfacies and predicted favorable sand bodies. The Putaohua reservoir consists of various sedimentary microfacies including distributary channels, interdistributary channels, mouth bars, front sheet sand, front delta mud and shallow lake mud, with sediments mainly sourced from the north and the west. It is of a typical shallow-delta deposit characterized by poor-developed mouth bars but wide front sheet sandstones. From bottom to top, the thickness and the grain size of sandstone layers increase with the lake level dropping, indicating a progradational stratigraphic sequence. In addition, the areas of front sheet sandstones also enlarge upwards and their shapes change from EW-trending strips in the lower part into large sheets in the upper part. The provenance is mainly located in the north at the early stage, while is mainly located in the west at the late stage. The early banded sand layers and the later large sheet-shape lenticular sand layers at the center of the sag are favorable sandbodies. Source

Li Z.,CAS Institute of Geology and Geophysics | Ma X.,CAS Institute of Geology and Geophysics | Ma X.,University of Chinese Academy of Sciences | Fu C.,Shenhua Geological Exploration Co. | Liang G.,CAS Institute of Geology and Geophysics
Journal of Applied Geophysics

In elastic reverse time migration (RTM), one of the problems that are often encountered is the cross-talk between P- and S-wavefields. A useful processing technique to reduce the cross-talk is separating the P- and S-wavefields by using divergence and curl operators before applying an elastic imaging condition. However, the separated wavefields lose their physical meaning because their phase and amplitude are changed. In this paper, we modify the divergence and curl operators to give the separated wavefields a clear physical meaning: the separated wavefield is the first derivative of the input wavefield with respect to time. Another problem often encountered is polarity reversals in PS and SP images, which can cause destructive interference in the final stacked image and thus destroy the migrated events. In this paper we also develop a procedure for polarity reversal correction based on the polarization vectors of the P- and S-wavefields in the common-shot domain. The correction factor is first calculated at every imaging point during the wavefield reconstruction and is then multiplied by the PS and SP images at each time step when an elastic imaging condition is applied. Numerical examples with synthetic data have shown that the modified wavefield separation method is correct, and the procedure of polarity reversal correction is effective for a complex model. © 2016 Elsevier B.V. Source

Liang F.,China Shenhua Overseas Development and Investment Company | Liu L.,Shenhua Geological Exploration Co. | Yu X.,China University of Geosciences | Huang Y.,China University of Geosciences | Tang H.,Xian Institute of Geology and Mineral Resources
Scientia Geologica Sinica

Structural accommodation zone, which is the main type of transfer zone, controls the sediments migration path and surface exhibition in the Shenxian Sag, Jizhong Depression. According to the characteristics of the faults combination(such as dip relation)and throw, four categories, 4 kinds of structural accommodation zones can be summed up. Controlled by basic structural configuration, single line and synthetic accommodation zones, which are relatively small and numerous, mainly develop in the northern part area, such as in Hezhuang, Bingcao and Cuijiazhuang. Convergent accommodation zones, however, which are larger and sparse, mainly formed in the southern part area, such as Yuke and western Zhaojiazhuang. Divergent accommodation zones are rarely found in the Shenxian Sag. Single line accommodation zones may allow minor sedimentary bodies acrossing faults and reaching faulted lake, such as subaqueous fans developed in downthrown side of Hengshui fault. Synthetic accommodation zones control the transportation path into the catchment basin and spread of braided delta in Hezhuang-Xiweicun, Tianjiazhuang, Dongyangxiang. Convergent accommodation zones usually lead to the formation of deep lake, for example in Zhaojiazhuang. Besides, Divergent accommodation zones usually block the sediment transportion by topographic high. Source

Zhang B.,Inner Mongolia Mining Exploitation Co. | Zhang B.,Shandong University of Science and Technology | Gao Z.,Shandong University of Science and Technology | Zhang F.,Inner Mongolia Mining Exploitation Co. | And 3 more authors.
Earth Science Frontiers

The hydrogeochemical zonations of geothermal water in North China Basin can be used to indicate the hydrodynamic zoning because the latter actively responded to the former. The quality of geothermal water is deteriorating and the deuterium-excess parameter decreases from surrounding mountains to the basin and from shallow to depth in North China Basin, suggesting that the rate of groundwater circulation become slower and slower. The distribution characteristics of high salinity zoning of geothermal water indicate that the Taihang Mountains and Yanshan Mountains in the west and north are predominant recharge area of geothermal water in North China Basin, while a small recharge amount is from the mountains in the southwest of Shandong Province. In addition, whether in the horizontal or vertical direction in the basin, the hydrogeochemical zonations also indicate that there is hydrodynamic equilibrium zone between the centripetal flow (infiltration original water) and acentric flow (sedimentary original water) of geothermal water in sandstone. This indicates that there is transient equilibrium between the centripetal flow and the acentric flow. © 2015, Editorial Office of Earth Science Frontiers. All right reserved. Source

Zhang J.,CAS Institute of Geology and Geophysics | Lu B.,Shenhua Geological Exploration Co. | Jing Y.,China National Offshore Oil Corporation | Qin P.,China National Petroleum Corporation
Journal of Seismic Exploration

A 3D illumination compensation and residual moveout method in the angle domain is developed to improve the quality of imaging for the data acquired by an irregular acquisition system. The approach uses the Kirchhoff integration migration to provide fast illumination analysis and amplitude compensation. A residual moveout function is presented and be used to flatten the events in the angle gather. In addition to the simple procedure and computational efficiency, the method can also avoid the singularity problem usually linked to the conventional ray tracing method. It provides a practical tool for 3D full-volume illumination analysis and extract high quality common-imaging gathers and migration sections for complicated geological structures. To demonstrate the potential application of this method, a 3D marine field-data is used to evaluate the effectiveness of our method. ©2014 Geophysical Press Ltd. Source

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