With the increasing complexity of wells being drilled to optimally access as much of the reservoir as possible, an integrated drilling risk assessment strategy needs to be presented to address the increasing level of challenges and risks. Wells are being drilled deeper, through intervals that are heavily depleted into virgin, unexplored reservoirs. They are extending outward to horizontal lengths that were not even dreamed of several years ago. The assessment process described in this publication incorporates a better understanding of the complex geologic environment such as a multitude of pressure compartments, complex faulting and lithological variations that could potentially increase the risk magnitude. With these challenges, there is a step change in understanding and quantifying these hazards, risk liabilities and uncertainties that need to be addressed to make these projects commercially viable and be able to drill down to their designed targets without cost overruns due to NPT, and not less important, keeping a stable borehole capable of being evaluated and resulting in successful production rate.
In order to address these challenges, more upfront in-depth planning and analysis must be performed. Often times, a review of the drilling issues are performed around symptoms of drilling events to respond to them, but not necessarily to determine why these events happened in the first place – the root cause. This shows when contingencies are built into a well plan to account for the NPT consequences of these drilling events observed in offset wells. In order to proactively address these increasing risks and hazards, development and incorporation of a detail risk mitigation strategy is required.
Through experience, leveraging drilling, geomechanical and geological models in the risk assessment process, has proven to be successful in understanding the hazards that are present. Bringing out the potential hazards is just part of the strategy. A multi-discipline team needs to analyze each potential hazard and determine the best mitigation strategy to mitigate that risk down to a safe, acceptable level. The collaboration of a multi-discipline team is the key component to understand all the different drilling, geological, geomechanical and fluids influences on the potential hazard. With this type of approach in assessing the risk, the process can then address all the potentially different variables required to design an intelligent, proactive drilling strategy. Even with the best strategy in place, there are geologic uncertainties that still need to be analyzed. Knowing these uncertainties, this multi-discipline team designs a mitigation strategy utilizing the right mix of technologies and real-time monitoring component to be able to update models to fine-tune the drilling window and to provide recommendations while drilling - to optimize the drilling process.
Showing that this process is effective, several results will be discussed, demonstrating the value of incorporating a pre-drill risk assessment along with real-time monitoring to reduce drilling time, uncertainties and to successfully provide safe and predictable operations from start to finish that provide ideal wellbore conditions for completion.
