The efficient development and exploitation of shale oil depends on long-distance horizontal wells. As the degreeof cleaning of the wellbore plays a key role in these processes, in this study, this problem is investiga...The efficient development and exploitation of shale oil depends on long-distance horizontal wells. As the degreeof cleaning of the wellbore plays a key role in these processes, in this study, this problem is investigated experimentallyby focusing on the dimensionless cuttings bed height. A method is proposed to calculate the horizontalwellhydraulic extension taking into account the influence of the wellbore cleaning degree on the wellborepressure distribution and assess the effect of a variety of factors such as the bottom hole pressure, the circulatingpressure drop, the drilling pump performance and the formation properties. The analysis shows that the hydraulicextension of horizontal wells decreases with an increase in the cuttings bed height, and the higher the displacementof drilling fluid, the faster the hydraulic extension declines. The annular pressure drop of the horizontalsection increases with the increase of the cuttings bed height, resulting in a higher bottom-hole pressure. Severalarguments are provided to guide the safe drilling of shale oil horizontal wells and overcome the limits of currenttechnological approaches.展开更多
Resistivity will have different response characteristics to the hydraulic fracture propagation process. In this work, a resistivity testing system for hydraulic fracturing specimens was established. Resistivity and ac...Resistivity will have different response characteristics to the hydraulic fracture propagation process. In this work, a resistivity testing system for hydraulic fracturing specimens was established. Resistivity and acoustic emission(AE) information were jointly analysed to determine the dynamic response characteristics of resistivity during hydraulic fracture propagation. The results show that the water and fracture exert a competitive influence on the connection structure of the circuit, and there are two significant peak resistivity points in the curve, presenting a double peak therein. The peak resistivity data of the specimen with a larger fracture area are much different from the initial value. With the increase of the rate of injection, the range of variation of the highest value that can be reached with the specimen resistivity decreases. High resistivity rates or high resistivity fluctuations exhibit rapid a release of fracture energy. The fracture failure mode dominated by shear fractures makes the formation produce a “series+parallel” electrical connection structure;a calculation model of formation resistivity based on shear and tensile failure was proposed to characterize the proportion of different types of hydraulic fractures and elucidate the control effect of matrix resistivity on the electrical performance of the overall circuit structure.展开更多
How long the ultra deep well can extend and what is the ultra deep well's maximum hydraulic extension depth are always concerned and studied by drilling engineers. The well's maximum hydraulic extension depth ...How long the ultra deep well can extend and what is the ultra deep well's maximum hydraulic extension depth are always concerned and studied by drilling engineers. The well's maximum hydraulic extension depth can be predicted by the maximum hydraulic extension depth prediction model. To overcome the disadvantage that previous prediction model did not consider the effects of temperature and only applies to horizontal wells, a prediction model of maximum hydraulic extension depth for ultra deep wells considering effects of temperature is established. Considering the effects of temperature coupled with the constraints of drilling pump rated pressure and rated power, the prediction result of ultra deep well's maximum hydraulic extension depth is modified. An ultra deep well developed by Sinopec in Shunbei oilfield, China, is analyzed, and its wellbore temperature profile and maximum hydraulic extension depth are analyzed and predicted. Results show that the maximum hydraulic extension depth with considering temperature is larger than that without considering temperature. With the identical depth, the higher inlet temperature and the greater geothermal gradient mean the higher drilling fluid temperatures in the drill string and annulus as well as the larger maximum hydraulic extension depth. Besides, the maximum depth decreases with the increase in drilling fluid flow rate and density, while it increases with the increase in drilling pump rated pressure and rated power. To ensure the designed depth can be reached, there exists the maximum drilling fluid flow rate and density, as well as the minimum drilling pump rated pressure and rated power. This study is important for accurately predicting the ultra deep well's maximum depth within the limit capacity of drilling pump. In addition, it also plays a major role in avoiding drilling hazards.展开更多
为从系统整体角度完成对起落架收放系统的风险辨识和影响分析,将系统理论过程分析(Systematic Theory Process Analysis,STPA)与决策实验室分析-解释结构模型(Decision Making Trial and Evaluation Laboratory Interpretive Structural...为从系统整体角度完成对起落架收放系统的风险辨识和影响分析,将系统理论过程分析(Systematic Theory Process Analysis,STPA)与决策实验室分析-解释结构模型(Decision Making Trial and Evaluation Laboratory Interpretive Structural Modeling,DEMATEL-ISM)相结合来开展分析。首先,定义事故和系统级危险,以民机进近阶段放下起落架为例,运用STPA完成对风险因素的系统化辨识;其次,基于最大平均熵减(Maximum Mean De-entropy,MMDE)算法帮助DEMATEL-ISM模型确定阈值,完成对风险因素影响的重要性分析并识别可能引发系统级危险的风险传递路径,据此挖掘关键致因场景,以给出风险预防建议。结果显示:线路性能退化或失效、位置作动控制组件(Position Action Control Unit,PACU)核心处理器故障为关键原因因素,收放作动筒作动异常、机组成员操作不当、起落架指示灯显示异常、起落架液压选择阀作动异常、PACU信息接收有误为关键结果因素,这些因素均涉及多条可能引发系统级危险的风险传递路径,应予以重点控制。展开更多
基金supported by CNPC Key Core Technology Research Projects (2022ZG06)project funded by China Postdoctoral Science Foundation (2021M693508)Basic research and strategic reserve technology research fund project of institutes directly under CNPC.
文摘The efficient development and exploitation of shale oil depends on long-distance horizontal wells. As the degreeof cleaning of the wellbore plays a key role in these processes, in this study, this problem is investigated experimentallyby focusing on the dimensionless cuttings bed height. A method is proposed to calculate the horizontalwellhydraulic extension taking into account the influence of the wellbore cleaning degree on the wellborepressure distribution and assess the effect of a variety of factors such as the bottom hole pressure, the circulatingpressure drop, the drilling pump performance and the formation properties. The analysis shows that the hydraulicextension of horizontal wells decreases with an increase in the cuttings bed height, and the higher the displacementof drilling fluid, the faster the hydraulic extension declines. The annular pressure drop of the horizontalsection increases with the increase of the cuttings bed height, resulting in a higher bottom-hole pressure. Severalarguments are provided to guide the safe drilling of shale oil horizontal wells and overcome the limits of currenttechnological approaches.
基金supported by the National Key R&D Program of China (No. 2018YFC0807805)the National Natural Science Foundation of China (No. 52074049)。
文摘Resistivity will have different response characteristics to the hydraulic fracture propagation process. In this work, a resistivity testing system for hydraulic fracturing specimens was established. Resistivity and acoustic emission(AE) information were jointly analysed to determine the dynamic response characteristics of resistivity during hydraulic fracture propagation. The results show that the water and fracture exert a competitive influence on the connection structure of the circuit, and there are two significant peak resistivity points in the curve, presenting a double peak therein. The peak resistivity data of the specimen with a larger fracture area are much different from the initial value. With the increase of the rate of injection, the range of variation of the highest value that can be reached with the specimen resistivity decreases. High resistivity rates or high resistivity fluctuations exhibit rapid a release of fracture energy. The fracture failure mode dominated by shear fractures makes the formation produce a “series+parallel” electrical connection structure;a calculation model of formation resistivity based on shear and tensile failure was proposed to characterize the proportion of different types of hydraulic fractures and elucidate the control effect of matrix resistivity on the electrical performance of the overall circuit structure.
基金supported by Sinopec Research Institute of Petroleum Engineering,Beijing,Chinathe National Natural Science Foundation of China (Grant No. 51821092)+1 种基金the New Technology for Design and Control of Complex Well and Cluster Well (Grant No. 2017ZX05009-003)the Key Technology of Drilling Technology and Wellbore Working Fluid(Grant No. 2016YFC0303303)。
文摘How long the ultra deep well can extend and what is the ultra deep well's maximum hydraulic extension depth are always concerned and studied by drilling engineers. The well's maximum hydraulic extension depth can be predicted by the maximum hydraulic extension depth prediction model. To overcome the disadvantage that previous prediction model did not consider the effects of temperature and only applies to horizontal wells, a prediction model of maximum hydraulic extension depth for ultra deep wells considering effects of temperature is established. Considering the effects of temperature coupled with the constraints of drilling pump rated pressure and rated power, the prediction result of ultra deep well's maximum hydraulic extension depth is modified. An ultra deep well developed by Sinopec in Shunbei oilfield, China, is analyzed, and its wellbore temperature profile and maximum hydraulic extension depth are analyzed and predicted. Results show that the maximum hydraulic extension depth with considering temperature is larger than that without considering temperature. With the identical depth, the higher inlet temperature and the greater geothermal gradient mean the higher drilling fluid temperatures in the drill string and annulus as well as the larger maximum hydraulic extension depth. Besides, the maximum depth decreases with the increase in drilling fluid flow rate and density, while it increases with the increase in drilling pump rated pressure and rated power. To ensure the designed depth can be reached, there exists the maximum drilling fluid flow rate and density, as well as the minimum drilling pump rated pressure and rated power. This study is important for accurately predicting the ultra deep well's maximum depth within the limit capacity of drilling pump. In addition, it also plays a major role in avoiding drilling hazards.
文摘为从系统整体角度完成对起落架收放系统的风险辨识和影响分析,将系统理论过程分析(Systematic Theory Process Analysis,STPA)与决策实验室分析-解释结构模型(Decision Making Trial and Evaluation Laboratory Interpretive Structural Modeling,DEMATEL-ISM)相结合来开展分析。首先,定义事故和系统级危险,以民机进近阶段放下起落架为例,运用STPA完成对风险因素的系统化辨识;其次,基于最大平均熵减(Maximum Mean De-entropy,MMDE)算法帮助DEMATEL-ISM模型确定阈值,完成对风险因素影响的重要性分析并识别可能引发系统级危险的风险传递路径,据此挖掘关键致因场景,以给出风险预防建议。结果显示:线路性能退化或失效、位置作动控制组件(Position Action Control Unit,PACU)核心处理器故障为关键原因因素,收放作动筒作动异常、机组成员操作不当、起落架指示灯显示异常、起落架液压选择阀作动异常、PACU信息接收有误为关键结果因素,这些因素均涉及多条可能引发系统级危险的风险传递路径,应予以重点控制。
