Based on the Dikken analytical calculation method of wellbore pressure loss under single-phase fluid and turbulent flow conditions, the correlation model between horizontal well output and horizontal section length an...Based on the Dikken analytical calculation method of wellbore pressure loss under single-phase fluid and turbulent flow conditions, the correlation model between horizontal well output and horizontal section length and horizontal section distributed pressure difference is constructed. The influence degree of wellbore pressure loss on daily oil production of horizontal well, horizontal section pressure and production effect of horizontal well under different horizontal well lengths is analyzed, which provides certain reference for the design of horizontal well length and well layout.展开更多
为了解决顺北油田二叠系钻进过程中漏失严重的问题,分析了顺北二叠系地层特征、漏失类型及裂缝宽度,揭示了二叠系漏失原因,总结了该油田防漏堵漏技术发展历程及取得的技术成果,并就目前面临的难题给出了技术攻关建议。分析可知,二叠系...为了解决顺北油田二叠系钻进过程中漏失严重的问题,分析了顺北二叠系地层特征、漏失类型及裂缝宽度,揭示了二叠系漏失原因,总结了该油田防漏堵漏技术发展历程及取得的技术成果,并就目前面临的难题给出了技术攻关建议。分析可知,二叠系地层破碎,多尺度复杂裂缝发育,漏失压力低,裂缝对井筒压力敏感,是造成地层漏失的主要原因。针对二叠系漏失,经历“逢漏就堵”、“避免承压”、“塌漏同治”及“优化完善”四个阶段,形成了随钻防漏、桥堵、随钻堵漏、凝胶堵漏、化学固结和全井堵漏浆等技术。2018年以来,在顺北蓬1、顺北鹰1等20余口井应用,单井平均漏失量由2017年之前的508 m 3降低为2020年的138 m 3(降低72.8%),单井堵漏时间由2017年之前的9.3 d降到2020年的2.6 d(降低72%),现场应用效果良好。展开更多
For proper water management in the new reclaimed areas, hydraulic parameters of both aquifer and wells related to transmissivity, specific capacity, well loss, formation loss, and water entrance velocity, as well as t...For proper water management in the new reclaimed areas, hydraulic parameters of both aquifer and wells related to transmissivity, specific capacity, well loss, formation loss, and water entrance velocity, as well as the relationship between these parameters are the main target after construction of production wells. In El Shab area, the Nubian Sandstone aquifer has a large range of transmissivity (from 483.12 to 1489.24 m2/day) and, also, specific capacity (from 203 to 486.32 m2/day). Relationship of specific capacity and transmissivity is constructed and the established empirical equations can be used to predict the transmissivity of the Nubian aquifer in all new proposed sites for well drilling at which the specific capacity measured without performing pumping tests. On the other hand, the drilled wells in El Shab area exhibit relatively high well losses (25%). The causes for high well losses (entrance velocity (Vn) through water well screen and the distance from the point of water entrance in the well to the point of intake in the pump) are discussed and the relationships are constructed, which seem a positive linear correlation. Relationships between well losses constant for 30 wells with transmissivity and specific capacity, are constructed. These relationships are useful for estimating hydraulic characteristics that are needed for the designs of wells and well fields and for preliminary water-resources management.展开更多
It is important to determine quantitatively the internal carrier loss arising from heating and barrier height variation in a vertical-cavity surface-emitting quantum well laser （VCSEL）. However, it is generally diff...It is important to determine quantitatively the internal carrier loss arising from heating and barrier height variation in a vertical-cavity surface-emitting quantum well laser （VCSEL）. However, it is generally difficult to realize this goal using purely theoretical formulas due to difficulty h, deriving the parameters relat^i~g to the quantum well structure. In this paper, we describe an efl：icient approach to characterizing and calculating the carrier loss due to the heating and the barrier height change in the VCSEL. In the method, the thermal carrier loss mechanism is combined with gain measurement and calculation. The carrier loss is re-characterized in a calculable form by constructing the threshold current and gain detuning-related loss current using the measured gain data and then substituting them for the quantum well-related parameters in the formula. The result can be expressed as a product of an exponential weight factor linked to the barrier height change and the difference between the threshold current and gain detuning-related loss current. The gain variation at cavity frequency due to thermal carrier loss and gain detuning processes is measured by using an AllnGaAs-AIGaAs VCSEL structure. This work provides a useful approach to analysing threshold and loss properties of the VCSEL, particularly, gain offset design for high temperature operation of VCSELs.展开更多
Tuberculosis has traditionally been found to occur with weight loss or at least failure to gain weight. Atypical and unusual presentations of various types of tuberculosis have been reported but limited data is availa...Tuberculosis has traditionally been found to occur with weight loss or at least failure to gain weight. Atypical and unusual presentations of various types of tuberculosis have been reported but limited data is available on tuberculosis in well-nourished children with no weight loss. Two case reports from our experience highlight well-nourished children with histologically diagnosed tuberculosis that presented with atypical symptoms and no evidences of weight loss. The usefulness of histological diagnosis cannot be overemphasized. This report aims to highlight this unusual presentation of tuberculosis so as to increase the index of suspicion for early diagnosis and hence, prompt treatment of tuberculosis in this group of children.展开更多
文摘Based on the Dikken analytical calculation method of wellbore pressure loss under single-phase fluid and turbulent flow conditions, the correlation model between horizontal well output and horizontal section length and horizontal section distributed pressure difference is constructed. The influence degree of wellbore pressure loss on daily oil production of horizontal well, horizontal section pressure and production effect of horizontal well under different horizontal well lengths is analyzed, which provides certain reference for the design of horizontal well length and well layout.
文摘为了解决顺北油田二叠系钻进过程中漏失严重的问题,分析了顺北二叠系地层特征、漏失类型及裂缝宽度,揭示了二叠系漏失原因,总结了该油田防漏堵漏技术发展历程及取得的技术成果,并就目前面临的难题给出了技术攻关建议。分析可知,二叠系地层破碎,多尺度复杂裂缝发育,漏失压力低,裂缝对井筒压力敏感,是造成地层漏失的主要原因。针对二叠系漏失,经历“逢漏就堵”、“避免承压”、“塌漏同治”及“优化完善”四个阶段,形成了随钻防漏、桥堵、随钻堵漏、凝胶堵漏、化学固结和全井堵漏浆等技术。2018年以来,在顺北蓬1、顺北鹰1等20余口井应用,单井平均漏失量由2017年之前的508 m 3降低为2020年的138 m 3(降低72.8%),单井堵漏时间由2017年之前的9.3 d降到2020年的2.6 d(降低72%),现场应用效果良好。
基金National Natural Science Foundation of China(No.62204127)the Natural Science Foundation of Jiangsu Province(No.BK20215093)State Key Laboratory of Luminescence and Applications(No.SKLA‒2021‒04)。
文摘For proper water management in the new reclaimed areas, hydraulic parameters of both aquifer and wells related to transmissivity, specific capacity, well loss, formation loss, and water entrance velocity, as well as the relationship between these parameters are the main target after construction of production wells. In El Shab area, the Nubian Sandstone aquifer has a large range of transmissivity (from 483.12 to 1489.24 m2/day) and, also, specific capacity (from 203 to 486.32 m2/day). Relationship of specific capacity and transmissivity is constructed and the established empirical equations can be used to predict the transmissivity of the Nubian aquifer in all new proposed sites for well drilling at which the specific capacity measured without performing pumping tests. On the other hand, the drilled wells in El Shab area exhibit relatively high well losses (25%). The causes for high well losses (entrance velocity (Vn) through water well screen and the distance from the point of water entrance in the well to the point of intake in the pump) are discussed and the relationships are constructed, which seem a positive linear correlation. Relationships between well losses constant for 30 wells with transmissivity and specific capacity, are constructed. These relationships are useful for estimating hydraulic characteristics that are needed for the designs of wells and well fields and for preliminary water-resources management.
文摘It is important to determine quantitatively the internal carrier loss arising from heating and barrier height variation in a vertical-cavity surface-emitting quantum well laser （VCSEL）. However, it is generally difficult to realize this goal using purely theoretical formulas due to difficulty h, deriving the parameters relat^i~g to the quantum well structure. In this paper, we describe an efl：icient approach to characterizing and calculating the carrier loss due to the heating and the barrier height change in the VCSEL. In the method, the thermal carrier loss mechanism is combined with gain measurement and calculation. The carrier loss is re-characterized in a calculable form by constructing the threshold current and gain detuning-related loss current using the measured gain data and then substituting them for the quantum well-related parameters in the formula. The result can be expressed as a product of an exponential weight factor linked to the barrier height change and the difference between the threshold current and gain detuning-related loss current. The gain variation at cavity frequency due to thermal carrier loss and gain detuning processes is measured by using an AllnGaAs-AIGaAs VCSEL structure. This work provides a useful approach to analysing threshold and loss properties of the VCSEL, particularly, gain offset design for high temperature operation of VCSELs.
文摘Tuberculosis has traditionally been found to occur with weight loss or at least failure to gain weight. Atypical and unusual presentations of various types of tuberculosis have been reported but limited data is available on tuberculosis in well-nourished children with no weight loss. Two case reports from our experience highlight well-nourished children with histologically diagnosed tuberculosis that presented with atypical symptoms and no evidences of weight loss. The usefulness of histological diagnosis cannot be overemphasized. This report aims to highlight this unusual presentation of tuberculosis so as to increase the index of suspicion for early diagnosis and hence, prompt treatment of tuberculosis in this group of children.
