Publications

The well design paradigm in one of Suban wells marked a departure from the traditional approach employed in previous Suban wells, which consistently featured four casing strings – 30", 20", 13-3/8", and 9-5/8" in size. This uniform well design, prevalent since the initial drilling in 1972, reflected the conservatism mandated by the substantial subsurface uncertainties associated with exploration wells.

However, a growing portfolio of exploration and appraisal wells provided an opportunity to enhance the efficiency of development well designs by leveraging a deeper understanding of subsurface conditions. Collaborative efforts within the team led to an evaluation of innovative optimization opportunities, with a keen focus on cost efficiency. One such innovation involved the reduction of casing strings, transitioning from the conventional four to three casing sizes: 20", 13-3/8", and 9-5/8".

The endeavor to reduce casing strings encompassed four key domains:
• Pore Pressure Analysis: Thorough analysis of pore pressure dynamics.
• Ground Water Protection: Measures to safeguard against ground water ingress.
• Conductor Loading and Thermal Cycling: Assessing structural integrity under loading and thermal stresses.
• Risk Mitigation: Strategies for minimizing operational risks.

The outcome of this pioneering approach culminated in the successful drilling of one of Suban wells, accomplishing the objective with just three casing strings prior to reservoir zone penetration. Notably, the predictions regarding the absence of shallow gas were substantiated. This innovative casing design not only realized material cost savings but also significantly reduced drilling time. Its implementation marked a watershed moment in the Corridor block, serving as the foundational template for future well designs.