In the Ecuadorian jungle, operators use the same location to drill several deviated wells. The geometries of these "S" or "J" type wells present high dogleg severity (DLS) in different sections, requiring rotation and reaming of the casing string to reach the target depth. During the rotation in deviated sections, the combination of the resultant bending of the string and its rotation generate alternating stresses in the pipe body and the connections. Likewise, contact forces on the string during the process promote the increase of drag and torque that the casing string has to withstand during its installation. These service characteristics can lead to create the conditions for potential fatigue and over-torque damages in the components of the casing strings installed in these wells.
In order to reduce the occurrence of over-torque failures in the casing threaded connections, a detailed engineering analysis was performed. This analysis includes the use of a torque and drag model for simulations, as well as the selection and application of a connection in which has been incorporated torque shoulders and a controlled pin nose geometry.
The objective of this paper is to present the strategy applied to achieve the reduction failure occurrence and promote the time optimization during the casing running in these directional wells. Additionally, in order to show the most significant improvements of running casing strings taking into account the recommendations of the engineering analysis, some results obtained from the pilot phase of the overall project are also presented in this paper. Actually, a summary of all strings with this technology installed during the last three years in the country is included.
It is important to mention that after the pilot phase, Shaya Ecuador standardized the new connection for the production casing and liner of these wells. From the moment this connection was implemented, 82 strings (production casing and liner) have been run in both 9-5/8" and 7" sizes, successfully reaching all the target depths without any problems.