Drillstring Vibration Analysis in Extended Reach Drilling (ERD) using WELLPLANTM

Oil and gas industry always aims efficient service with optimal expenses. This final
year project, aiming to deal with one of the most important parameters, that has
tremendous impact on drilling operations’ time and cost. This parameter as mentioned
above on the topic is a Drillstring Vibrations.
While drilling, Drillstring Vibration causes premature drillstring components and bit
failure [8], and is a waste of drilling energy. To increase drilling efficiency, drillstring
vibrations need to be monitored and analyzed and the optimum drilling parameters and
practices need to be achieved as a well is being drilled. This results in a reduction in the
drillstring failures and the amount of time spent tripping and/or fishing, and an increase
in both bit life and drilling rate.
Drillstring dynamics is one of the most important limiting factors in extended reach
drilling. This is because, long sections of the drillstring lie on the low side of the
wellbore while rotating. When the rotary speed exceeds a critical threshold the
drillstring starts to snake, sliding up and down the borehole wall [1]. If rotated further
beyond the threshold speed, the drillstring will eventually start to whir which can cause
severe damage to string components after only a short period of time [1]. Therefore, the
main scope of the project, considering the earlier mentioned issues, a WELLPLAN
software (Critical Speed Module) used. The project mainly dealt with drillstring, axial
stress, bending stresses and torsional oscillations known as stick-slip motion of the bit.
Besides the WELLPLANTM software, a matlab M.file was developed that uses some
predetermined equations to estimate the critical drillstring vibrations, and critical
operational speed taking into account the weight on bit, BHA length and rock
compressive strength