Study On Reciprocating Friction And Wear Behavior Between Tubing And Casing

In the process of well completion and production, the axial force will cause tubing to buckle and contact with the casing. Especially at the high temperature and high pressure (HTHP) underground environment, the wear between the tubing and casing, which due to axial vibration and radial pressure, will lead to tubing break even well failure.In this paper, a tubing and casing materials reciprocating wear test apparatus with intellectual property rights was used in tubing-casing wear experiments. The main work of experiments was the acquisition of value of wear weight loss, friction coefficient and friction work in every time step. There were some measurements obtained by mass loss method such as wall thickness thinning rate and the wear efficiency between Super-13Cr tubing materials and P110, TP140two kinds of casing materials. In addition, the mathematical regression method also used to fit the parameters about wall thickness thinning rate and wear efficiency under different conditions. By combining with the analysis of topography of sample, furthermore, by using Scanning Electron Microscope(SEM), it can find out the friction discipline and study on wear mechanism between tubing materials and casing materials.Experimental results showed that:In the modified drilling fluid medium, hardness of casing, positive pressure between tubing and casing, and friction frequency between tubing and casing were the main factors of casing wear against tubing. The main conclusions are as follows:(1) The effect of materials hardness on the wear is mainly manifested in two aspects. For one thing, the higher hardness casing will cause more serious abrasive wear to tubing. For another thing, smaller hardness between wearing materials were easier to occur adhesive wear.(2) The increasing positive pressure leaded to two samples tightly contacted with each other, so the wear rate increased rapidly too.(3) The experimental results show that the amount of wear increases with increase of friction frequency, because of the increase of adhesive wear.(4) By investigating the wear features of casing and tubing materials with time going on, the results showed that characteristics of wear between casing and tubing didn’t follow with time changed under the same working conditions. (5) In the process of wear experiment, the friction coefficient was stably fluctuating at around0.3under the same environmental medium, and the state of surface fatigue wear didn’t follow with the condition changing.