Performing simulation study on drill string mechanics, Torque and Drag.

Abstract

In this thesis work, a simulation and monitoring study was carried based on operational data obtained from two wells. These are South Sangu-4 and Sangu-11, which are situated in block 16. From the study it was found out that: Comparing the simulation data and real time data, the tripping in and tripping out coefficient of friction were back calculated .The coefficient of frictions derived from Sangu-4 were used for planning of drilling in Sangu-11. Calculating the Friction factor ratio on South Sangu-4, it shows an indication of Pack off around 3000m (MD) to 3500m (MD). And eventually the well (South sangu4) took a kick at the depth of 3486m (MD). No real time Torque and Drag monitoring was done there. Getting the idea of the FF of that block 16, a simulation of drill string stresses, Hook Load and Torque was carried out based on the planned survey data. From the study, it was found that the Torque at higher Friction Factor will cross the limit of make-up torque which may cause the failure of the drill string. Based on the simulation the real time Hook Load and Torque data were monitored. The monitoring results investigated indication of higher Torque in real time for which Lubricant was added in the mud to reduce the Torque in safe limit. One most important observation in 8.5’’ section was that the non-rotating protectors were not effectively reducing the Torque. Rather the use of lubricant controls the Torque in desired limit