Detailed information is provided for the design and construction of nitrogen drilling in a coal seam.Two prototype wells are considered.The Guo model is used to calculate the required minimum gas injection rate,while ...Detailed information is provided for the design and construction of nitrogen drilling in a coal seam.Two prototype wells are considered.The Guo model is used to calculate the required minimum gas injection rate,while the Finnie,Sommerfeld,and Tulsa models are exploited to estimate the ensuing erosion occurring in pipe strings.The calculated minimum gas injection rates are 67.4 m^(3)/min(with water)and 49.4 m^(3)/min(without water),and the actual field of use is 90–120 m^(3)/min.The difference between the calculated injection pressure and the field value is 6.5%–15.2%(formation with water)and 0.65%–7.32%(formation without water).The results show that the Guo model can more precisely represent the situation of the no water formation in the nitrogen drilling of a coal seam.The Finnie,Sommerfeld,and Tulsa models have different sensitivities to cutting densities,particle size,impact velocity and angle,and pipe string hardness.展开更多
The main failure modes of tubing and casing in current service conditions are represented in this study.The progress of the tubing and casing application technology and the problems that should be focused on during ap...The main failure modes of tubing and casing in current service conditions are represented in this study.The progress of the tubing and casing application technology and the problems that should be focused on during application are introduced,with special attention paid to the reliability of the pipe string design and the connection sealing properties.The necessary work that should be undertaken in future research is also summarized.展开更多
Background Coiled tubing operation is a high-quality operation method that considers both cost and efficiency in current oil and gas well operations.There is a significant difference between the calculation and predic...Background Coiled tubing operation is a high-quality operation method that considers both cost and efficiency in current oil and gas well operations.There is a significant difference between the calculation and prediction before operation and the actual operation.The reason is that the complex wellbore trajectory makes it difficult to evaluate the contact state between coiled tubing and wellbore,resulting in a significant error in the pipe string mechanics calculation and analysis.Methods In this study,a digital twin-based method for continuous tubing wear modelling is proposed.Firstly,the digital twin unit of continuous tubing-wellbore is constructed to achieve the fusion modelling of three types of information,namely structure,physical field and material,of the micro-element well section.On this basis,a feedbackcorrected contact algorithm is introduced to dynamically identify and correct the contact state of continuous tubing under different downhole running trajectories.By constructing a spatial and temporal two-dimensional digital twin of the continuous tubing operation process,the accurate positioning and historical state tracing of the tubing entity in the complex downhole environment are realised.Results The research results show that the digital twin coiled tubing and contact algorithm can effectively predict the contact state of coiled tubing operations;the verification model shows that the contact algorithm can accurately analyze the contact state of different well trajectories.Conclusions The digital twin of the coiled tubing operation structure and its contact algorithm can effectively solve the problem of deterministic friction state in the process of mechanical calculation of the tubing string,which has important guiding significance and engineering value for the mechanical calculation and operation safety analysis of coiled tubing operation.展开更多
基金National Science and Technology Major Special Project,2016ZX05044CBM Development Technology and Pilot Test in East Yunnan and Western Guizhou.
文摘Detailed information is provided for the design and construction of nitrogen drilling in a coal seam.Two prototype wells are considered.The Guo model is used to calculate the required minimum gas injection rate,while the Finnie,Sommerfeld,and Tulsa models are exploited to estimate the ensuing erosion occurring in pipe strings.The calculated minimum gas injection rates are 67.4 m^(3)/min(with water)and 49.4 m^(3)/min(without water),and the actual field of use is 90–120 m^(3)/min.The difference between the calculated injection pressure and the field value is 6.5%–15.2%(formation with water)and 0.65%–7.32%(formation without water).The results show that the Guo model can more precisely represent the situation of the no water formation in the nitrogen drilling of a coal seam.The Finnie,Sommerfeld,and Tulsa models have different sensitivities to cutting densities,particle size,impact velocity and angle,and pipe string hardness.
文摘The main failure modes of tubing and casing in current service conditions are represented in this study.The progress of the tubing and casing application technology and the problems that should be focused on during application are introduced,with special attention paid to the reliability of the pipe string design and the connection sealing properties.The necessary work that should be undertaken in future research is also summarized.
基金supported by the Scientific Research Program Funded by Shaanxi Provincial Education Department under contact No.21JP096.
文摘Background Coiled tubing operation is a high-quality operation method that considers both cost and efficiency in current oil and gas well operations.There is a significant difference between the calculation and prediction before operation and the actual operation.The reason is that the complex wellbore trajectory makes it difficult to evaluate the contact state between coiled tubing and wellbore,resulting in a significant error in the pipe string mechanics calculation and analysis.Methods In this study,a digital twin-based method for continuous tubing wear modelling is proposed.Firstly,the digital twin unit of continuous tubing-wellbore is constructed to achieve the fusion modelling of three types of information,namely structure,physical field and material,of the micro-element well section.On this basis,a feedbackcorrected contact algorithm is introduced to dynamically identify and correct the contact state of continuous tubing under different downhole running trajectories.By constructing a spatial and temporal two-dimensional digital twin of the continuous tubing operation process,the accurate positioning and historical state tracing of the tubing entity in the complex downhole environment are realised.Results The research results show that the digital twin coiled tubing and contact algorithm can effectively predict the contact state of coiled tubing operations;the verification model shows that the contact algorithm can accurately analyze the contact state of different well trajectories.Conclusions The digital twin of the coiled tubing operation structure and its contact algorithm can effectively solve the problem of deterministic friction state in the process of mechanical calculation of the tubing string,which has important guiding significance and engineering value for the mechanical calculation and operation safety analysis of coiled tubing operation.
