With estimated shale gas resources greater than those of US and Canada combined, China has been embarking on an ambitious shale development program. However, nearly 30 years of American experience in shale hydrocarbon...With estimated shale gas resources greater than those of US and Canada combined, China has been embarking on an ambitious shale development program. However, nearly 30 years of American experience in shale hydrocarbon exploration and production indicates a low total recovery of shale gas at 12 %-30 % and tight oil at 5 %-10 %. One of the main barriers to sustainable devel- opment of shale resources, namely the pore structure （ge- ometry and connectivity） of the nanopores for storing and transporting hydrocarbons, is rarely investigated. In this study, we collected samples from a variety of leading hydrocarbon-producing shale formations in US and China. These formations have different ages and geologic char- acteristics （e.g., porosity, permeability, mineralogy, total organic content, and thermal maturation）. We studied their pore structure characteristics, imbibition and saturated diffusion, edge-accessible porosity, and wettability with four complementary tests： mercury intrusion porosimetry, fluid and tracer imbibition into initially dry shale, tracer diffusion into fluid-saturated shale, and high-pressure Wood＇s metal intrusion followed with imaging and ele- mental mapping. The imbibition and diffusion tests use tracer-bearing wettability fluids （API brine or n-decane） to examine the association of tracers with mineral or organic matter phases, using a sensitive and micro-scale elemental laser ablation ICP-MS mapping technique. For two molecular tracers in n-decane fluid with the estimated sizes of 1.39 nm x 0.29 nm x 0.18 nm for 1-iododecane and 1.27 nm ~ 0.92 nm ~ 0.78 nm for trichlorooxobis （triph- enylphosphine） rhenium, much less penetration was observed for larger molecules of organic rhenium in shales with median pore-throat sizes of several nanometers. This indicates the probable entanglement of sub-nano-sized molecules in shales with nano-sized pore-throats. Overall findings from the above innovative approaches indicate the limited accessibility （several millimeters from sample edge） and connectivity of tortuous nanopore spaces in shales with spatial wettability, which could lead to the low overall hydrocarbon recovery because of the limited frac- ture-matrix connection and migration of hydrocarbon molecules from the shale matrix to the stimulated fracture network.展开更多
Temporal lobe resection is an important treatment option for epilepsy that involves removal of potentially essential brain regions. Selective amygdalohippocampectomy is a widely performed temporal lobe surgery. We sug...Temporal lobe resection is an important treatment option for epilepsy that involves removal of potentially essential brain regions. Selective amygdalohippocampectomy is a widely performed temporal lobe surgery. We suggest starting the incision for selective amygdalohippocampectomy at the inferior temporal gyrus based on diffusion magnetic resonance imaging（MRI） tractography. Diffusion MRI data from 20 normal participants were obtained from Parkinson＇s Progression Markers Initiative（PPMI） database（www.ppmi-info.org）. A tractography algorithm was applied to extract neuronal fiber information for the temporal lobe, hippocampus, and amygdala. Fiber information was analyzed in terms of the number of fibers and betweenness centrality. Distances between starting incisions and surgical target regions were also considered to explore the length of the surgical path. Middle temporal and superior temporal gyrus regions have higher connectivity values than the inferior temporal gyrus and thus are not good candidates for starting the incision. The distances between inferior temporal gyrus and surgical target regions were shorter than those between middle temporal gyrus and target regions. Thus, the inferior temporal gyrus is a good candidate for starting the incision. Starting the incision from the inferior temporal gyrus would spare the important（in terms of betweenness centrality values） middle region and shorten the distance to the target regions of the hippocampus and amygdala.展开更多
For solving the operation problems of floating liquefied natural gas(FLNG)vessels in harsh sea areas,especially in the areas where typhoon happens frequently,the characteristics of cyclone(typhoon)in China sea areas w...For solving the operation problems of floating liquefied natural gas(FLNG)vessels in harsh sea areas,especially in the areas where typhoon happens frequently,the characteristics of cyclone(typhoon)in China sea areas were analyzed based on the environmental conditions of the South China Sea.Then,the FLNG vessel connection operation and the FLNG vessel disconnection and evacuation plans in the situation of cyclones were compared.And finally,a series of research was carried out on the technical difficulties related to the FLNG vessel connection operation plan,such as the temperature field of LNG cofferdam,the vapor treatment and diffusion during a cyclone,such as a typhoon,and the typhoon generator at the shallow-water platform.Based on these analysis and research,the following recommendations were proposed.First,it is recommended to adopt the FLNG vessel connection operation plan during a typhoon to guarantee convenient and safe operation and to improve oil and gas field benefits.Second,a ballast cabin can be set inside the vessel to ensure the safety of Grade E steel in FLNG vessel,especially during a typhoon.Third,BOG diffusion can be still safe in the most dangerous working condition when the vent pipe reaches a certain height during a typhoon.Fourth,four groups of mooring systems(five pieces in each group)can be designed to guarantee the mooring strength of FLNG vessel connection operation during a typhoon.And fifth,when a typhoon arrives,it is necessary to stop FLNG production,release the pressure and organize personnel evacuation in a planned way.After the typhoon leaves,personnel return and FLNG production starts again.In this way,efficiency can be increased effectively,and the operational convenience and safety of FLNG vessels can be ensured.展开更多
基金Funding for this project was partially provided by the following three State Key Laboratories in China: State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Chengdu University of Technology, Chengdu (PLC-201301)State Key Laboratory of Organic Geochemistry, Chinese Academy of Sciences, Guangzhou (No. OGL-201402)the Foundation of State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum, Beijing (No. PRP/open-1403)
文摘With estimated shale gas resources greater than those of US and Canada combined, China has been embarking on an ambitious shale development program. However, nearly 30 years of American experience in shale hydrocarbon exploration and production indicates a low total recovery of shale gas at 12 %-30 % and tight oil at 5 %-10 %. One of the main barriers to sustainable devel- opment of shale resources, namely the pore structure （ge- ometry and connectivity） of the nanopores for storing and transporting hydrocarbons, is rarely investigated. In this study, we collected samples from a variety of leading hydrocarbon-producing shale formations in US and China. These formations have different ages and geologic char- acteristics （e.g., porosity, permeability, mineralogy, total organic content, and thermal maturation）. We studied their pore structure characteristics, imbibition and saturated diffusion, edge-accessible porosity, and wettability with four complementary tests： mercury intrusion porosimetry, fluid and tracer imbibition into initially dry shale, tracer diffusion into fluid-saturated shale, and high-pressure Wood＇s metal intrusion followed with imaging and ele- mental mapping. The imbibition and diffusion tests use tracer-bearing wettability fluids （API brine or n-decane） to examine the association of tracers with mineral or organic matter phases, using a sensitive and micro-scale elemental laser ablation ICP-MS mapping technique. For two molecular tracers in n-decane fluid with the estimated sizes of 1.39 nm x 0.29 nm x 0.18 nm for 1-iododecane and 1.27 nm ~ 0.92 nm ~ 0.78 nm for trichlorooxobis （triph- enylphosphine） rhenium, much less penetration was observed for larger molecules of organic rhenium in shales with median pore-throat sizes of several nanometers. This indicates the probable entanglement of sub-nano-sized molecules in shales with nano-sized pore-throats. Overall findings from the above innovative approaches indicate the limited accessibility （several millimeters from sample edge） and connectivity of tortuous nanopore spaces in shales with spatial wettability, which could lead to the low overall hydrocarbon recovery because of the limited frac- ture-matrix connection and migration of hydrocarbon molecules from the shale matrix to the stimulated fracture network.
基金supported by the National Research Foundation of Korea,No.20100023233
文摘Temporal lobe resection is an important treatment option for epilepsy that involves removal of potentially essential brain regions. Selective amygdalohippocampectomy is a widely performed temporal lobe surgery. We suggest starting the incision for selective amygdalohippocampectomy at the inferior temporal gyrus based on diffusion magnetic resonance imaging（MRI） tractography. Diffusion MRI data from 20 normal participants were obtained from Parkinson＇s Progression Markers Initiative（PPMI） database（www.ppmi-info.org）. A tractography algorithm was applied to extract neuronal fiber information for the temporal lobe, hippocampus, and amygdala. Fiber information was analyzed in terms of the number of fibers and betweenness centrality. Distances between starting incisions and surgical target regions were also considered to explore the length of the surgical path. Middle temporal and superior temporal gyrus regions have higher connectivity values than the inferior temporal gyrus and thus are not good candidates for starting the incision. The distances between inferior temporal gyrus and surgical target regions were shorter than those between middle temporal gyrus and target regions. Thus, the inferior temporal gyrus is a good candidate for starting the incision. Starting the incision from the inferior temporal gyrus would spare the important（in terms of betweenness centrality values） middle region and shorten the distance to the target regions of the hippocampus and amygdala.
文摘For solving the operation problems of floating liquefied natural gas(FLNG)vessels in harsh sea areas,especially in the areas where typhoon happens frequently,the characteristics of cyclone(typhoon)in China sea areas were analyzed based on the environmental conditions of the South China Sea.Then,the FLNG vessel connection operation and the FLNG vessel disconnection and evacuation plans in the situation of cyclones were compared.And finally,a series of research was carried out on the technical difficulties related to the FLNG vessel connection operation plan,such as the temperature field of LNG cofferdam,the vapor treatment and diffusion during a cyclone,such as a typhoon,and the typhoon generator at the shallow-water platform.Based on these analysis and research,the following recommendations were proposed.First,it is recommended to adopt the FLNG vessel connection operation plan during a typhoon to guarantee convenient and safe operation and to improve oil and gas field benefits.Second,a ballast cabin can be set inside the vessel to ensure the safety of Grade E steel in FLNG vessel,especially during a typhoon.Third,BOG diffusion can be still safe in the most dangerous working condition when the vent pipe reaches a certain height during a typhoon.Fourth,four groups of mooring systems(five pieces in each group)can be designed to guarantee the mooring strength of FLNG vessel connection operation during a typhoon.And fifth,when a typhoon arrives,it is necessary to stop FLNG production,release the pressure and organize personnel evacuation in a planned way.After the typhoon leaves,personnel return and FLNG production starts again.In this way,efficiency can be increased effectively,and the operational convenience and safety of FLNG vessels can be ensured.
