Effect of different roll-forming flower patterns on coiled tubing ovality and pressure performance

Abstract

The pressure applied by the drilling fluid circulation pumps into Coiled Tubing (CT) compensates for the effects of fluid friction and force applied to the downhole motors. The higher the pressure, the greater the power of the well operation. The critical point of the cross-section of CT is on the earth's surface, where the highest internal and lowest external pressure are applied to it. In this paper, the compressive tolerance value of CT is investigated in relation to its ovality. This ovality can be inherent and created during the construction of the tube. 4 different flower patterns can be used for making CT. This paper aims to roll forming CT without a sizing step so that it preserves its mechanical performance against incoming forces. The geometry-based form definition method calculations have been used to determine the forming path of the strip, and this is the basis for the design of the forming rollers in each stage, finally, according to the similarities in the forming stages, 45 rollers have been designed for simulation. Therefore, assuming that the sizing step is not used in tube roll forming, the effect of roll forming flower patterns on the ovality of the final product of 1 ½ inch CT-70 and its effect on the internal and external pressure tolerance of the tube is investigated and Results of dimensional analysis, a tensile test of a new QT-70, 1 ½ inch tube as a sample and the geometry-based form definition method results are considered as input for the simulation of all four methods and the finite element method was used to simulate tube construction with different flower pattern methods, and its results were used in the geometry of the final product, in CT pressure tolerance analysis. The results show that the behavior of the tube made by the reverse bending flower pattern method shows better tolerance against internal and external pressure so this behavior is related to the ratio of internal to external pressure tolerance in the tube. With the flower pattern method, the reverse bending is approximately 1.08–1.85 times compared to the double-radii pattern and 1.13 to 2.27 times, and 1.18 to 3.21 times compared to the edge flower pattern and circular flower patterns, respectively.