Addressing the challenges of drilling the Cretaceous formations of the Middle Magdalena Valley Basin in Colombia which present a difficult geologic environment characterized by high structural complexity, faulting, and uncertainties regarding operational windows, required the consideration of controlled pressure conditions and the use of two-phase fluid on continuous nitrogen injection. Also, to achieve wellbore displacement enhancing recovery, required a high-angle directional trajectory that involved close directional control and the identification and analysis of operational risks. Therefore, careful planning during the design phase was crucial. This involved identifying a set of engineering practices, mapping operational risks, and offering integrated solutions. Additionally, a thorough analysis of available options and selection of technologies that align with project requirements and challenges was necessary. Furthermore, the incorporation of bottomhole pressure sensors (PWD) was necessary to provide a reliable source of information for personnel in charge of monitoring bottomhole conditions and overseeing nitrogen injection, so that the information collected could be reviewed in real time to determine the effectiveness of the operational parameters implemented and to evaluate unexpected conditions.
The results indicated a smooth trajectory with minimal deviations, meeting the directional requirements as modeled by the directional BHA. A limited percentage of detection and data transmission through pulse signals to the surface was deemed acceptable. Additionally, the implementation of automation using service provider proprietary software became feasible.
The main challenges encountered when drilling a naturally fractured limestone reservoirs involves minimizing formation damage resulting from circulation losses. To address this issue, a solution was implemented utilizing Managed Pressure Drilling (MPD) and the injection of Nitrogen as a bi-phasic fluid. The objective of this approach was to generate a controlled Equivalent Circulating Density (ECD) in order to minimize fluid invasion and effectively manage fluid losses.
The main difficulty lied in drilling a high angle well in a complex geological environment with significant structural complexities. The operational window was uncertain, necessitating consideration of two-phase fluid conditions and continuous nitrogen injection. Additionally, it was crucial to maintain directional control and meet specific requirements for capturing logging information. To address these challenges, a comprehensive operational risk analysis was conducted, and the appropriate selection of tools and techniques was made to efficiently gather information in harsh conditions. This enabled the reduction of decision-making times and the achievement of operational efficiencies based on real-time data collection.
