Bending of coiled tubing at the bottom hole and the wellhead
The article deals with the loss of coiled tubing stability under the action of axial compressive load, both at the bottom hole, and on the wellhead. The values of the critical axial forces of the first and second order are obtained. It has been established that in the bottom hole coiled tubing almost always loses its straight shape in a vertical well and becomes spatially spiraling. The results of calculations are also given, proving the fact that in wells with an inclined wellbore the coiled tubing spatial bending is not inevitable. The results of calculations of the axial compressive force for a coiled tubing section located at the wellhead are presented and analyzed. It has been established that the cause of the coiled tubing bending and destruction between the injector and the sealing element of the sealing agent can be formation of a gas-hydrate ice massif; this fact is confirmed in practice.