Experimental Study On Casing Wear In Ultra-deep Wells In An Oil Field

Due to the use of a new type of wellbore structure in an oilfield in China,the oil casing is mainly made of the high steel grade casing,and the drilling fluid system and performance have also changed,resulting in changes in casing wear.Therefore,it is necessary to study the wear law of high steel grade casings currently used in the oilfield.In this paper,the physical experiment and theoretical analysis method are used to study the wear law and wear mechanism of a 140 ksi high steel grade casing.The following law is obtained: in D drilling fluid,when the lateral force increases from 44094N/m to 66141N/m,the casing wear rate increases significantly,and the wear factor increases slightly;wear performance of ARNCO 350 XT hardbanding is better than the ARNCO 100XT;for the A and B drilling fluids,when the drilling fluid density increases,the casing wear rate is slightly increased,while the wear rate under D drilling fluid is significantly increased.For C drilling fluid,when the mass ratio of barite and iron ore fines in drilling fluid is B:F=6.69:1,The casing wear rate and wear factor are low;if the barite powder content in the drilling fluid is too high,the wear factor will increase;the proportion of barite and iron ore powder in the drilling fluid will lead to an increase in the wear factor and the casing wear will increase.For D drilling fluid,when the mass ratio of barite and iron ore fines in drilling fluid is B:F=10.72:1,the wear factor will increase significantly,when the lateral force increases from 44094N/m to66141N/m,the fatigue wear of the casing is aggravated.Therefore,the oil field should minimize the lateral force of the wellbore when designing the wellbore trajectory.For high-density drilling fluids,the content,type,and proportion of the weighting agent will have a greater impact on casing wear.Therefore,more research on drilling fluid weighting agents should be carried out in the oil field in the future.