Offshore wind turbines(OWTs) suffer wind, wave and earthquake loads. The investigation of OWTs' dynamic response under environmental loads is essential for structural safety assessment. The soil-structure interact...Offshore wind turbines(OWTs) suffer wind, wave and earthquake loads. The investigation of OWTs' dynamic response under environmental loads is essential for structural safety assessment. The soil-structure interaction(SSI)significantly affects the responses of OWT under environmental loads. However, there is few systematic research about the difference in the dynamic response of different SSI models under environmental loads. In order to solve the problem, the OWT is modeled by shell element, and several SSI models are built. The wind, wave and earthquake loads are taken into account. Moreover, the dynamic response, fatigue and buckling analysis are performed by ANSYS. The results indicate that SSI cannot be ignored in the dynamic response of the OWT under wind and wave loads. The SSI can decrease the displacement response of the OWT by 19% under wind and wave loads and reduce the fatigue damage of the pile. Multi-layer SSI can strongly influence the OWT's dynamic response under wind and wave loads or earthquake-only load. The vertical earthquake load increases the dynamic response in three directions.Besides, in order to simulate real environment, multi-layer SSI, soil damping and vertical SSI must be considered to evaluate the displacement response of the OWT under wind, wave and earthquake loads. The earthquake and gravity loads can cause more obvious response of the OWT than that of only wind and wave loads. The top and bottom of the tower are prone to occur buckling.展开更多
Oil and gas exploration in lacustrine mud shale has focused on laminated calcareous lithofacies rich in type Ⅰ or type Ⅱ1 organic matter, taking into account the mineralogy and bedding structure, and type and abunda...Oil and gas exploration in lacustrine mud shale has focused on laminated calcareous lithofacies rich in type Ⅰ or type Ⅱ1 organic matter, taking into account the mineralogy and bedding structure, and type and abundance of organic matter. Using the lower third member of the Shahejie Formation, Zhanhua Sag, Jiyang Depression as the target lithology, we applied core description, thin section observations, electron microscopy imaging, nuclear magnetic resonance, and fullbore formation microimager （FMI） to study the mud shale lithofacies and features. First, the lithofacies were classified by considering the bedding structure, lithology, and organic matter and then a lithofacies classification scheme of lacustrine mud shale was proposed. Second, we used optimal filtering of logging data to distinguish the lithologies. Because the fractals of logging data are good indicators of the bedding structure, gamma-ray radiation was used to optimize the structural identification. Total organic carbon content （TOC） and pyrolyzed hydrocarbons （S2） were calculated from the logging data, and the hydrogen index （HI） was obtained to identify the organic matter type of the different strata （HI vs Tmax）. Finally, a method for shale lithofacies identification based on logging data is proposed for exploring mud shale reservoirs and sweet spots from continuous wellbore profiles.展开更多
Diagenetic fluid types of the Cretaceous Bashijiqike formation are restored based on the analysis of petrographic,electron microprobe composition,inclusions homogenization temperature,salinity and vapor composition an...Diagenetic fluid types of the Cretaceous Bashijiqike formation are restored based on the analysis of petrographic,electron microprobe composition,inclusions homogenization temperature,salinity and vapor composition and laser carbon and oxygen isotope of diagenetic mineral,and regional geological background.Diagenetic fluid evolution sequence is analyzed on this basis.The crystalline dolomite cement has a low concerntration of Sr,high concerntration of Mn and higher carbon isotope,showing that the crystalline dolomite is affected by meteoric fresh water,associated with the tectonic uplift of late Cretaceous.Similarδ13CPDB,negative transfer ofδ18OPDB and the differentiation of the concerntration of Fe and Mn indicate that the diagenetic fluid of the vein dolomite cement is homologous with the diagenetic fluid of the crystalline dolomite cement,temperature and depth are the dominant factors of differential precipitation between these two carbonate cements.Anhydrite cements have high concerntration of Na,extremely low concerntration of Fe and Mn contents.Based on these data,anhydrite cements can be thought to be related to the alkaline fluid overlying gypsum-salt layer produced by dehydration.The barite vein has abnormally high concerntration of Sr,ultra-high homogenization temperature and high-density gas hydrocarbon inclusions,which is speculated to be the forward fluid by intrusion of late natural gas.Coexistence of methane inclusions with CO2 gas proves existence of acid water during the accumulation of natural gas in the late stages.Therefore,the alkaline environment and associated diagenesis between the meteoric fresh water in epidiagentic stage and carbonic acid in the late diagenesis have dominated the process of diagenesis and reservoir,the secondary porosity and fracture zone formed by gas accumulation is a favorable play for the exploration of ultra-deep reservoirs.展开更多
Based on the drilling,cores,logs,seismic,laboratory analysis and so on,reservoir characteristics and hydrocarbon accumulation of Carboniferous volcanic weathered crust in Zhongguai high area are studied.Volcanic rocks...Based on the drilling,cores,logs,seismic,laboratory analysis and so on,reservoir characteristics and hydrocarbon accumulation of Carboniferous volcanic weathered crust in Zhongguai high area are studied.Volcanic rocks were formed in an island arc environment.The lithology is mainly andesite and tuff;Reservoir spaces are mainly secondary pore,fracture and their combination forms,fractures have a better effect on reservoir seepage;There are four layer structures of volcanic weathered crust,weathered clay layer,strongly weathered zone,weakly weathered zone and unweathered zone and strongly weathered zone is the best,which is the main reservoir development zone;The development of reservoir is mainly affected by weathering-leaching,lithology and lithofacies,and fault(fracture);Effective reservoirs could reach to 480 m thickness(high quality reservoirs are within 240 m).Carboniferous volcanic reservoirs are distributed along three zones,which are near the fault zone,high structural part,favorable lithofacies development zone,and one plane,which is near the unconformity.展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos. 51976131, 52006148, and 52106262)。
文摘Offshore wind turbines(OWTs) suffer wind, wave and earthquake loads. The investigation of OWTs' dynamic response under environmental loads is essential for structural safety assessment. The soil-structure interaction(SSI)significantly affects the responses of OWT under environmental loads. However, there is few systematic research about the difference in the dynamic response of different SSI models under environmental loads. In order to solve the problem, the OWT is modeled by shell element, and several SSI models are built. The wind, wave and earthquake loads are taken into account. Moreover, the dynamic response, fatigue and buckling analysis are performed by ANSYS. The results indicate that SSI cannot be ignored in the dynamic response of the OWT under wind and wave loads. The SSI can decrease the displacement response of the OWT by 19% under wind and wave loads and reduce the fatigue damage of the pile. Multi-layer SSI can strongly influence the OWT's dynamic response under wind and wave loads or earthquake-only load. The vertical earthquake load increases the dynamic response in three directions.Besides, in order to simulate real environment, multi-layer SSI, soil damping and vertical SSI must be considered to evaluate the displacement response of the OWT under wind, wave and earthquake loads. The earthquake and gravity loads can cause more obvious response of the OWT than that of only wind and wave loads. The top and bottom of the tower are prone to occur buckling.
基金This work was supported by the National Natural Science Foundation of China （Nos. 41202110 and 51674211） and Open Fund of State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation （Southwest Petroleum University） （No. PLN201612）, the Applied Basic Research Projects in Sichuan Province （No. 2015JY0200） and the Open Fund Project from Sichuan Key Laboratory of Natural Gas Geology （No. 2015trqdz07）.
文摘Oil and gas exploration in lacustrine mud shale has focused on laminated calcareous lithofacies rich in type Ⅰ or type Ⅱ1 organic matter, taking into account the mineralogy and bedding structure, and type and abundance of organic matter. Using the lower third member of the Shahejie Formation, Zhanhua Sag, Jiyang Depression as the target lithology, we applied core description, thin section observations, electron microscopy imaging, nuclear magnetic resonance, and fullbore formation microimager （FMI） to study the mud shale lithofacies and features. First, the lithofacies were classified by considering the bedding structure, lithology, and organic matter and then a lithofacies classification scheme of lacustrine mud shale was proposed. Second, we used optimal filtering of logging data to distinguish the lithologies. Because the fractals of logging data are good indicators of the bedding structure, gamma-ray radiation was used to optimize the structural identification. Total organic carbon content （TOC） and pyrolyzed hydrocarbons （S2） were calculated from the logging data, and the hydrogen index （HI） was obtained to identify the organic matter type of the different strata （HI vs Tmax）. Finally, a method for shale lithofacies identification based on logging data is proposed for exploring mud shale reservoirs and sweet spots from continuous wellbore profiles.
基金Projects(51674211,51534006)supported by the National Natural Science Foundation of China
文摘Diagenetic fluid types of the Cretaceous Bashijiqike formation are restored based on the analysis of petrographic,electron microprobe composition,inclusions homogenization temperature,salinity and vapor composition and laser carbon and oxygen isotope of diagenetic mineral,and regional geological background.Diagenetic fluid evolution sequence is analyzed on this basis.The crystalline dolomite cement has a low concerntration of Sr,high concerntration of Mn and higher carbon isotope,showing that the crystalline dolomite is affected by meteoric fresh water,associated with the tectonic uplift of late Cretaceous.Similarδ13CPDB,negative transfer ofδ18OPDB and the differentiation of the concerntration of Fe and Mn indicate that the diagenetic fluid of the vein dolomite cement is homologous with the diagenetic fluid of the crystalline dolomite cement,temperature and depth are the dominant factors of differential precipitation between these two carbonate cements.Anhydrite cements have high concerntration of Na,extremely low concerntration of Fe and Mn contents.Based on these data,anhydrite cements can be thought to be related to the alkaline fluid overlying gypsum-salt layer produced by dehydration.The barite vein has abnormally high concerntration of Sr,ultra-high homogenization temperature and high-density gas hydrocarbon inclusions,which is speculated to be the forward fluid by intrusion of late natural gas.Coexistence of methane inclusions with CO2 gas proves existence of acid water during the accumulation of natural gas in the late stages.Therefore,the alkaline environment and associated diagenesis between the meteoric fresh water in epidiagentic stage and carbonic acid in the late diagenesis have dominated the process of diagenesis and reservoir,the secondary porosity and fracture zone formed by gas accumulation is a favorable play for the exploration of ultra-deep reservoirs.
基金Project (51674211) supported by the National Natural Science Foundation of ChinaProject (51534006) supported by the Key Projects of the Natural Science Foundation,ChinaProject (2017ZX05036003-003) supported by the National Science and Technology Project of China
文摘Based on the drilling,cores,logs,seismic,laboratory analysis and so on,reservoir characteristics and hydrocarbon accumulation of Carboniferous volcanic weathered crust in Zhongguai high area are studied.Volcanic rocks were formed in an island arc environment.The lithology is mainly andesite and tuff;Reservoir spaces are mainly secondary pore,fracture and their combination forms,fractures have a better effect on reservoir seepage;There are four layer structures of volcanic weathered crust,weathered clay layer,strongly weathered zone,weakly weathered zone and unweathered zone and strongly weathered zone is the best,which is the main reservoir development zone;The development of reservoir is mainly affected by weathering-leaching,lithology and lithofacies,and fault(fracture);Effective reservoirs could reach to 480 m thickness(high quality reservoirs are within 240 m).Carboniferous volcanic reservoirs are distributed along three zones,which are near the fault zone,high structural part,favorable lithofacies development zone,and one plane,which is near the unconformity.
