RESEARCH AND STUDIES ON FLEXIBLE TUBING WEARING

Flexible tubing (coiled tubing) demonstrated its capabilities and has been becoming nowadays a necessity in the oil and gas industry. Within the applications of flexible tubing have to be mentioned inclined drilling or horizontal drilling, cleaning clogged wells, interventions on wells both on production wells and during the drilling activities. The flexible tubing used in exploitation and/or operating the wells should meet the following requirements: tensile strength resistance collapse resistance, fatigue strength, corrosion resistance and resistance to fragilizant factors. In particular, the damages that may occur with respect to the functionality loss of flexible tubing are manifested by breakage or loss of tightness, excessive plastic deformation, bumping, and breakage. During the use of the flexible tubing in the well, it undergoes a series of stresses that lead to wear and degradation, changes in dimensional, geometric and mechanical characteristics. The paper presents the theoretical and experimental studies performed in order to establish the admissibility conditions regarding the mechanical and dimensional characteristics (shape deviations) of the material, the influence of working environments on the state of operation of the flexible tubing.