Abdul Rahman, Norain (Petronas Carigali) | Mohaideen, Azlan (Petronas Carigali) | Bakar, Farah Hanim (Petronas Carigali Sdn Bhd) | Tang, Kien Hoe (Schlumberger WTA Malaysia S/B) | Maury, Radha (Schlumberger) | Cox, Paul (Schlumberger) | Le, Phi (Schlumberger) | Donald, Hugh (Smith Bits, A Schlumberger Company) | Brahmanto, Edwin (Schlumberger) | Subroto, Bramanta (Schlumberger)
In mid 2010, Petronas Carigali (PCSB) initiated a drilling campaign of a green field development at the Malay Basin, offshore Peninsular Malaysia. The operator is required to drill a borehole through a challenging interbedded formation with hard streaks calcareous to access natural gas reserves in one of the fields. In two development wells, stick-slip reached an unacceptable level increasing the risk of tool failure while driving up field development costs. The operator required an analysis methodology to ascertain the root cause of drilling dysfunction to optimize the bottom hole assembly (BHA) design and drilling parameters to mitigate vibration and improve drilling performance. To solve the problem, a finite element analysis (FEA) based modeling system was employed to analyze application details from the previous two wells and derive an improvement scheme.
Drilling dynamics data and logging information was collected along with operating parameters, mud logs and PDC bit dull grades. Additional problems were identified included hole washout, insufficient WBM lubricity and issues with a reaming stabilizer. An advanced rock-strength analysis system was used to determine unconfined compressive strength (UCS) of the interbedded formation.
Once all issues had been identified, the model was calibrated and readied for dynamic simulation. A variety of BHA configurations and PDC bits were run under different drilling conditions and operating parameters. The results of the simulations provided sufficient insight to the cause of the high levels of lateral and torsional vibration.
Using the knowledge gains, engineers selected the most appropriate PDC bit and BHA configuration. An optimum range of operating parameters with different weight on bit/revolutions per minute combinations were provided to field personnel to ensure the highest possible rate of penetration (ROP) and still remain in the established low vibration window.
The modeling effort proved successful and the third well was drilled with significantly lower torsional vibration compared to the first two wells. This paper will detail the collaboration and integrated approach of the service company in determining vibration issues and solving the problem, hence enhancing the drilling performance of upcoming wells.
Phase 1: Drilling Data Analysis
During this part of the analysis, the initial available post drilling data obtained was investigated in search for clues that might lead to the possible causes of vibration. More focus was placed on analyzing Well 2 as there were more recorded data available for this operation (Figure 1).