Study On Abrasion And Protection Of Well Casing In Drilling Process

In the actual drilling process,the condition is very complicated and not easy to control,which will cause casing wear and leads to many adverse consequences.In the subsequent construction process,casing wear will have a great impact on completion,oil production and even the subsequent well repair.In this paper,the mechanism of casing wear is analyzed,and the rule of casing wear and common wear patterns are analyzed too.The most typical crescent shaped wear was studied and the amount of abrasion loss,the residual wall thickness,wear area are deduced.the corresponding formulas are given.The influencing factors of casing wear,such as contact force,friction coefficient,friction distance and so on,are analyzed.Wear prediction model of casing and drill pipe was established.Because of the casing wear,the wall will become thinner and the corresponding will cause the change of their own strength.By means of finite element analysis,the strength of casing after abrasion is analyzed,including two aspects: anti collapse strength and internal pressure strength.The corresponding calculation formulas are given,and the factors which influence the strength are also analyzed.Finally,it is concluded that the residual strength of casing is smaller with the increase of wear degree.Finally we summarized the anti wear measures,including reducing the coefficient of friction,reducing contact force,reducing the friction distance,setting the abrasion preventing device,the measures of casing wear underground treatment and so on.It also puts forward some suggestions for the improvement of various measures,which provides a basse for casing wear prevention in the actual production process.