Mechanical Analysis Of Gas Production Pipe String And Optimization Design Of Pipe String Structure In Keshen Block

Gas production pipe string,as an important transportation channel for underground gas,plays an important role in gas field development.The Keshen block has the characteristics of deep gas reservoir burial,high formation pressure,and high bottom hole temperature.The stress conditions of the gas production pipe string are extremely complicated.The block gas production string is faced with problems such as difficult material selection and frequent failures.The mechanical analysis of the gas production pipe string in Keshen block and the research on the optimization design of the pipe structure have certain theoretical value and practical significance for the preparation and deployment of the development plan.Based on summarizing domestic and foreign gas production string models,this article establishes a gas production string model suitable for the Keshen block,conducts gas production string mechanical analysis and optimizes the design of the string structure,and mainly completes the following:(1)Considering the influence of internal pressure,external pressure,axial force,formation temperature and other factors on the strength of the pipe string,a reasonable simplified assumption was made on the force of the gas string,and a gas string model in keshen block was established by using finite element analysis software.(2)Based on the principle of gas well productivity analysis,and using node analysis software,calculate the gas well productivity in the Keshen block at different bottomhole pressures(50MPa,85 MPa,120MPa)different tubing sizes(2 3/8 ?,27/8 ?,3 1/2 ?,4 1/2 ?): The preliminary preferred gas production tubing strings are 3 1/2 ?,4 1/2 ? and 3 1/2 ?+4 1/2 ? combined tubing.(3)In view of the current operating conditions and material selection difficulties,several tubing process characteristics such as corrosion-resistant alloy tubing,horse-shaped stainless steel tubing,ordinary carbon steel tubing,and inner-coated tubing are analyzed.Horse-shaped stainless steel tubing is recommended.Three different gas production pipe string structural schemes are designed for the preliminary optimal combined oil pipe.The fourth-strength theory is used to check the safety factor of the dangerous section.The optimal pipe string scheme is 114.3×12.7mm S13 Cr 110800 m + 114.3×9.65 mm S13 Cr 110 700 m + 88.9×9.52 mm S13 Cr 110 1500 m +88.9×7.34 mm S13 Cr 110 1000 m + 88.9×6.45 mm S13 Cr 110 3600 m.(4)The results are applied to well A in Keshen block,and the designed pipe string structure can basically meet the requirements of safe production and acid fracture construction.