Since Tuesday’s Congressional hearing on the Gulf of Mexico accident and spill, a lot of people have asked me about ExxonMobil’s approach to designing and drilling wells.  For example, would we have used a long casing string or a liner/tieback to reduce the risk of a cement job failure?  Do we use the same approach with all wells?

My answer is — every well is different.  Effective casing design is complex and the approach to drilling each well must be tailored to the specific conditions involved.  Casing design incorporates a number of critical elements including pore pressure, location of hydrocarbon zones and formation integrity. The final design is a risked-based decision with the objective of achieving the highest degree of wellbore integrity for the condition of the specific well.

Both a long casing string and a liner/tieback are viable casing designs for deepwater; however, their specific application is dependent on individual well conditions.

For example, we have designed deepwater wells in the Gulf of Mexico with long, single-string casing in situations where we can reliably predict pressures and other conditions we’ll encounter as we drill the well. That’s the case around our Hoover Diana production platform in the Gulf, where we have drilled 17 wells and have a very detailed understanding of the geology.

At a new exploration well; however, less geological information means additional mitigation steps are needed given the greater range of uncertainty involved. The less you know, the more mitigation steps you need.

That’s a lot of technical language, I know. But it underscores an important point: It’s all about risk management.  At ExxonMobil, we rigorously apply our Operations Integrity Management System — and one of the 11 key elements is risk assessment – which gives us the safety framework for everything we do, including deepwater drilling.

Operations Integrity Management System calls for analyses of every significant operation we undertake around the world – in refineries, service stations, offshore platforms, and even in our offices. It identifies the risks to people and to the environment that are inherent in our business. And it requires procedures and processes to make sure we’re operating safely.