| With the increase of exploration and development of petroleum and natural gas,deep oil and gas resources are gradually being developed and utilized,and more wells under complex operating conditions,such as deep wells,ultra-deep wells,etc.With the increase of casing service time in old wells,the number of special wells such as horizontal wells increases.The problem of casing damage is also becoming more and more serious.such as the new 101 wells,Chuanxiao 565 wells,Dayi 101 wells,Dayi 4 wells,these problems on drilling production,especially the late development and utilization of troubled,Individual wells and even cause serious injury to the wellbore.It is generally believed that the quality of wellbore,well structure,casing material,drilling tool movement state and drilling fluid performance are the main causes of casing wear.The main forms of casing wear are adhesive wear,cutting wear,abrasion wear,contact fatigue Wear and abrasive wear.Based on the study of casing wear mechanism and the influencing factors of casing wear,this paper study the influence factors such as casing material,drilling fluid,borehole curvature and so on,considering the influence of different working conditions,friction coefficient and drill string buckling.A model for calculating the contact force between drill pipe and casing considering the buckling of drill string is established.The influence factors such as wear efficiency,slip distance of drill string,friction coefficient,lateral force between drill string and casing,speed of drill pipe are considered,and the prediction model of casing wear depth and volume of casing wear is established.The model of casing collapse strength and internal pressure strength is derived,and the influence of casing wear depth on casing strength is analyzed.Based on the analysis of the influencing factors of volume of casing wear,a new anti-friction and anti-friction technology of casing is put forward,and the double-effect anti-wear measures are put forward.The casing wear is further optimized by the casing wear prediction model and the double-effect anti-wear technology Forecasting model,improve anti-wear and anti-friction measures,put forward a more reasonable casing anti-friction and anti-friction measures.Research results showed that:the volume of-casing wear increases with the drilling time,the volume of casing wear increases with the contact force between the drill pipe and the casing,the volume of casing wear increases with the velocity of the drill pipe,the rotating velocity of drill pipe has little effect on the volume of casing wear.With the increase of casing wear thickness,the decrease percentage of wear casing collapsing strength increases linearly.The decrease percentage of collapsing strength of the N80 casing is larger than that of the P110 casing with the same volume of casing wear.With the increase of the wear thickness of the casing,the decrease percentage of the internal pressure strength of the N80 casing is increased linearly.The decrease percentage of internal pressure strength of N80 casing is greater than that of P110 casing with the same volume of casing wear.The double-effect anti-wear technology of the casing is better than that of the single-Or mechanical wear can reduce the wear of the drill pipe to the casing;New 202 ?193.7mm casing with AFC7101 drilling fluid with anti-wear agent and TFF non-metallic anti-wear joint anti-wear effect is obvious,the average loss of wear To 72.75%,to achieve the purpose of protection casing;Yuan dam 103H well construction difficult,the use of AFC7101 drilling fluid with anti-wear agent and TF metal anti-wear joint double-effect anti-wear technology program,a total consumption of drilling fluid with anti-wear agent 7.92 Ton,the use of metal anti-wear joints 29,29 joints test,from the drill grinding resistance and torque are not large,anti-wear effect is more obvious.Contents of this research on casing wear in deep and ultra deep wells prediction and anti-wear and friction reducing plays an important role in guiding. |
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