Realistic Approach to Improve Pump Start up Procedures
Research output: Research › Master's Thesis
The major objective of oil and gas operator companies isto increase the return on investment via increasingdrilling efficiency and minimizing drilling cost. Due to the resent oil price drastic drop and the downward pressures on the oil price, saving as much as possible is important today more than any time else. The cost of the well depends mainly on the time it takes to drill and complete it successfully.However, non-planned, unexpected events continue to plague the performance and the progress of drilling operations. These events are considered to create significant loss of time and productivity commonly referred to as non-productive time (NPT). One of the NPT contributors is wellbore stability. Wellbore stability can be improved with the help of detailed real time simulation of pressure in the wellbore which provides a better control on the wellbore via transferring the downhole parameters to the surface in real time. Nevertheless, the problem is that the real time simulation is costly and cannot be afforded for all wells. One of the issues related to wellbore stability is the mud pump start-up. The speed of how quickly the mud pumps are brought up during drilling operations has a big impact on the pressure regimes in the wellbore and wellbore stability. Drilling mud is designed to form a gelled structure under static condition to keep the cuttings and mud additives in suspension. Once the gelled structure is formed, higher energy is required to break it.A fast increase in the pump strokes increases the downhole pressure and generates a pressure spike, which might lead to several problems like formation fracture, lost circulation, etc. In contrast a slow increase in the pump strokes may lead to increase in overall invisible lost time. For decades, it was up to the driller how he thought it would be better to bring the pump up, however, today it is possible to simulate that and make it better.Hence, the conventional pump start-up procedure needs to be optimized taking into account several affecting parameters like wellbore and drill string geometry, mud characteristics and geologies, as well as other operating parameters.From this perspective the aim of this thesis is to define all the factors that might have impact on the pump start-up procedures and verify their impact by analysing historical data. Moreover, it will develop a new approach that will help to optimize the quality of the existing pump start-up producers. This approach integrates several downhole conditions to the known pump start up factors in order generate more reliable procedures.Finally, the steps of developing standard procedures in form of documentation and graphs based on the newly developed approach for various rigs operated by OMV worldwide are presented and discussed in details.