In an effort to reduce the shale gas exploration risks and costs, we applied the wide-field electromagnetic method （WFEM）, because of its strong anti-interference capability, high resolution, ability to conduct expl...In an effort to reduce the shale gas exploration risks and costs, we applied the wide-field electromagnetic method （WFEM）, because of its strong anti-interference capability, high resolution, ability to conduct exploration at large depths, and high efficiency, to the Bayan Syncline in the South Huayuan block, Hunan Province. We collected rock samples and analyzed their resistivity and induced polarization （IP） and built A series of two-dimensional models for geological conditions to investigate the applicability of WFEM to different geological structures. We also analyzed the correlation between TOC of shale and the resistivity and IP ratio to determine the threshold for identifying target formations. We used WFEM to identify the underground structures and determine the distribution, depth, and thickness of the target strata. Resistivity, IP, and total organic carbon were used to evaluate the shale gas prospects and select favorable areas （sweet spots） for exploration and development. Subsequently, drilling in these areas proved the applicability of WFEM in shale gas exploration.展开更多
高模态密度结构的宽频振动分析问题是声振分析领域内关注的重点问题之一,可实现宽频振动预测的数值分析方法是该领域内重要的研究内容,有效的宽频振动数值分析方法应在低频至高频域可同时提供精准的数值解。然而,由于明显的耗散误差和...高模态密度结构的宽频振动分析问题是声振分析领域内关注的重点问题之一,可实现宽频振动预测的数值分析方法是该领域内重要的研究内容,有效的宽频振动数值分析方法应在低频至高频域可同时提供精准的数值解。然而,由于明显的耗散误差和计算成本过高导致传统有限元方法(traditional finite element method,TFEM)在对高模态密度结构进行宽频振动分析时,难以在高频域提供精准的数值解,致使无法实现有效的宽频振动分析。而小波有限元分析方法(wavelet finite element method,WFEM)在进行结构分析时具有潜在的求解效率优势,并且可大幅度降低耗散误差带来的影响。为此,本文首先构造了基于小波有限元理论进行宽频振动分析时的自耦合算法,并据此介绍了小波有限元方法对高模态密度结构进行宽频振动分析的架构,形成了宽频小波有限元分析方法(wide wavelet finite element method,WWFEM)。随后,采用数值分析研究方法,基于WWFEM对具有解析解的高模态密度薄板结构进行了宽频振动分析。最后,采用实验分析研究方法,预测了高模态密度结构在宽频域内的振动响应。在此基础上,对比分析了小波有限元方法在进行高频振动分析时的收敛性和宽频振动分析的有效性等。可为依据小波有限元分析方法解决圆柱壳、曲壳等高模态密度结构宽频振动分析问题提供理论参考。展开更多
基金financially supported by the Thirteenth Five-Year-Plan Major Project "Marine Shale Gas Exploration and Evaluation over Laifengxianfeng and Hefeng Block"(No.2016ZX05034004-004)China Huadian Engineering Co.,LTD(No.CHEC-KJ-2014-Z10)
文摘In an effort to reduce the shale gas exploration risks and costs, we applied the wide-field electromagnetic method （WFEM）, because of its strong anti-interference capability, high resolution, ability to conduct exploration at large depths, and high efficiency, to the Bayan Syncline in the South Huayuan block, Hunan Province. We collected rock samples and analyzed their resistivity and induced polarization （IP） and built A series of two-dimensional models for geological conditions to investigate the applicability of WFEM to different geological structures. We also analyzed the correlation between TOC of shale and the resistivity and IP ratio to determine the threshold for identifying target formations. We used WFEM to identify the underground structures and determine the distribution, depth, and thickness of the target strata. Resistivity, IP, and total organic carbon were used to evaluate the shale gas prospects and select favorable areas （sweet spots） for exploration and development. Subsequently, drilling in these areas proved the applicability of WFEM in shale gas exploration.
文摘高模态密度结构的宽频振动分析问题是声振分析领域内关注的重点问题之一,可实现宽频振动预测的数值分析方法是该领域内重要的研究内容,有效的宽频振动数值分析方法应在低频至高频域可同时提供精准的数值解。然而,由于明显的耗散误差和计算成本过高导致传统有限元方法(traditional finite element method,TFEM)在对高模态密度结构进行宽频振动分析时,难以在高频域提供精准的数值解,致使无法实现有效的宽频振动分析。而小波有限元分析方法(wavelet finite element method,WFEM)在进行结构分析时具有潜在的求解效率优势,并且可大幅度降低耗散误差带来的影响。为此,本文首先构造了基于小波有限元理论进行宽频振动分析时的自耦合算法,并据此介绍了小波有限元方法对高模态密度结构进行宽频振动分析的架构,形成了宽频小波有限元分析方法(wide wavelet finite element method,WWFEM)。随后,采用数值分析研究方法,基于WWFEM对具有解析解的高模态密度薄板结构进行了宽频振动分析。最后,采用实验分析研究方法,预测了高模态密度结构在宽频域内的振动响应。在此基础上,对比分析了小波有限元方法在进行高频振动分析时的收敛性和宽频振动分析的有效性等。可为依据小波有限元分析方法解决圆柱壳、曲壳等高模态密度结构宽频振动分析问题提供理论参考。
