Utilizing Managed Pressure Casing Drilling in Depleted Reservoir Zones

Abstract

The last decade has seen the emergence of new unconventional drilling methods, such as Managed Pressure Drilling and Casing and Liner Drilling. Separately, these methods are proven to bring value to drilling operations if used in the right situations. At present, these technologies are treated as mutually exclusive. Managed Pressure Drilling involves drilling with a closed pressure envelope and applied backpressure. This feature provides greater control over the Bottom Hole Pressure, helps reduce time spent circulating in new mud, and may help extend casing points, reduce stuck pipe incidents and reduce the risk of well control incidents. Liner and Casing Drilling is often used when drilling through poorly consolidated and heavily fractured formations where wellbore collapse is a concern. The key benefit is that the wellbore is cased while drilling, so that the chance of losing the well is minimal.This thesis sets out to explore the benefits and limitations of combining these two methods. It has been found that they are complementary, provided that modifications are made to the top drive and Rotary Control Device. While combining the two is likely to lead to additional expenditures on the drilling side, it seems likely that such a combination may bring significant value to certain drilling operations. Managed Pressure Drilling and Casing/Liner Drilling are both ad hoc techniques, as is the case for the combination, dubbed Managed Pressure Casing Drilling. Examples of candidates thought to benefit from using this combination include: Highly depleted reservoirs Formations with very narrow mud windows Consecutive layers with different pressure regimesThough the added cost associated with such a combination is likely to be significant, the findings in this thesis indicates that there is a significant savings potential involved as well: Managed Pressure Casing Drilling may allow the Driller to improve the productivity of the well while drilling it faster, with fewer Flat Time and Health, Safety & Environment incidents. The technique is also thought to provide new opportunities for development of fields/reservoir pockets previously thought undrillable.