The aim of this paper/presentation is to highlight the recently introduced alternative drilling methods that are now being field trialed in ultra deep water. The objective of the new methodologies is to ‘drill the undrillable’. A number of underlying principles are utilized to achieve safe and cost effective bottom hole management to enable the drilling industry to realize target horizons that hitherto, in many problematic well cases, have been considered unreachable. There is no doubt that the Macondo disaster has been earmarked as a serious catalytic ‘wake up call’ which has resulted in accelerated funding into new innovative and enabling technologies to provide more safe and cost effective oil & gas exploration in ultra deep water field developments.
A number of supplementary systems have been introduced in parallel with adaptive drilling methods. Their application, whether an integral part of an adaptive method or else an optional stand-alone system is identified and discussed.
Four processes are presented, commencing with Conventional Riser Drilling (CRD). The other processes describe the principles of Managed Pressure Drilling (MPD), Dual Gradient Drilling (DGD) and the Pumped Riser System.
Further, to both compliment and supplement the above systems, a number of recent technology advancements are described. For example:- Early & Deep Water Kick Detection (EKD & DKD), Riser Gas Handling (RGH), Continuous Circulation System (CCS), Downhole Shut-Off Valves (DSVs) & Riserless Mud Recovery (RMR).
Throughout the latter quarter of 2014 and currently through this year (2015), the adaptive drilling methods being discussed in this paper are being field trialed. Such aspects, as economic drivers and safety assessments, remain in their infancy but trends of absolute proof of enhanced safety in drilling using one of the described methods is undeniable. All the upside/downside aspects are discussed, inclusive of operational continuity practical issues in the use of such systems throughout an extended drilling campaign (3-5 years).
CRD technology is historically rooted in the drilling industry, dating back to the ‘50s for offshore drilling. The methods are deeply entrenched in the offshore drilling culture with few refinements through the years, in spite of the advancement of exploration into deeper and deeper offshore acreages. The adaptive drilling methods described in this paper represent, in terms of drilling culture and established mindsets, a radical step change approach to drilling safely and effectively in ultra deep water. The new mental approach required for drilling crews using an adaptive drilling method makes the topics presented in this paper topical, necessary and illuminating.