| In this paper,HF161-Y161 wells in Iraq halfaya oilfield Yamama oil casing damage and its optimization,production tubing safety evaluation,carried out a systematic study.First,the development of Yamama layer system and the research of pipe string material selection are introduced and analyzed,and the safety evaluation of Yamama casing,casing failure cause analysis and casing damage mechanism are carried out.Finally,a mathematical model for completion string mechanics is established,and the development of its mechanical strength evaluation software is developed,which provides a reliable means for the optimal design and safety evaluation of Yamama reservoir.The main research content and research results of this paper are as follows:(1)The relevant literature and research status about casing damage and tubing and casing material selection at home and abroad are investigated.At the same time,the basic data of Yamama halfaya oilfield reservoir and casing related data were analyzed,including the main casing damage form,casing damage occurs,wellbore structure,casing and tubing design,cementing quality,stress data,provide on-site data for this study.(2)The problems in the design of casing and tubing column in Yamama oil reservoir are analyzed.The research results show that the original design scheme of casing and tail pipe production and the L-80 casing selected by the steel tube column at the Yamama level reservoir can resist H2S corrosion,but it does not resist CO2 corrosion.There is no H2S in this reservoir,but the content of CO2 is high;the production casing and tail pipe buckle type was BTC(buttress buckle),the buckle type leakage,poor sealing performance,due to the high CO2 content of dissolved gas in Yamama layer in high temperature and pressure,CO2 from BTC leakage and high salinity the formation water formed in acidic medium,and the corrosion of casing,providing the basis for selection of casing.(3)A mathematical model for casing safety evaluation is established.The safety and adaptability evaluation of strength design for production shaft strength of Y161 well 7 and Y161 well 41/2 is carried out.The cause of casing damage in HF161-Y161 well is analyzed,and a preliminary understanding is obtained.Meanwhile,a recommended practice for casing test,diagnosis and prevention is put forward.(4)The finite element solid model of casing and cement ring earth stress and its finite element mechanical model of Yamama layer were established,and the influence of cement ring intact,cement ring defect,perforation hole on casing Von Mises stress in cement sheath was obtained.The poor cementing quality and perforation parameters are easy to cause deformation and failure of casing under non uniform load.It is recommended that the casing and tailpipe material of Yamama reservoir should be C90-3Cr(anti CO2 corrosion)casing.The special type of airtight sealing buckle is adopted for the buckles,the 120 degree angle spiral perforation is adopted,and the cementing quality is ensured.(5)Analysis and Research on mechanical strength of completion pipe column.According to the collected analysis halfaya oilfield column design history data of the oil pipe,tubing with packer,based on the string and packer between the piston effect,spiral bending effect,bulking effect,temperature effect and fluid friction and pipe string friction effect.The establishment of the mechanics and the corresponding mathematical model,and the development of the analysis software completion pipe string mechanics analysis,mechanical strength,column strength of Yamama halfaya oil production to provide a theoretical basis for design. |
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