The Study On Casing Design In High Pressure Gas Wells

In recent years,with the increasing demand for oil and natural gas,high pressure gas well exploration has become a hot spot in the world today.The amount of deep high pressure gas wells is increasing rapidly,more challenges have occurred to the exploration and exploitation.In China,especially in Tarim Basin,deep oil and gas wells are faced with serious casing damage problems such as salt collapse and casing deformation after perforation.At the same time,for the gas has been buried much deeper,the pressure system underground is much complex,casing failure can not be avoided even if higher design factor is adopted.It indicates that the current casing design methology can not meet the need of deep and high pressure gas wells.So it is necessary to carry out relevant researches to improve the design method of casing string.In this paper,through analyzing and summarizing the domestic and international design methods of casing string,the casing loads under different working conditions are analyzed,the influence of temperature and salt formation are considered.When calculating the strength of casing string,the influence of corrosion,temperature as well as casing wear is disscussed.Based on the investigation of the domestic literature,the selection method of casing string and casing joint for deep and high pressure oil and gas well is recommended.Finally,aiming at the collapse problem of casing string in complicated salt formation in Kuche area,this paper puts forward the measures of controlling the pressure of the mud in the annular and adopting Pipe-in-pipe combination casing structure.