It has been stated many times that all the easy wells have been drilled. It would stand to reason then that only problem wells remain. Even though this last statement is not entirely correct, our industry is facing increasingly costly incidences of pressure-related nonproductive time. Problems include narrow pore-/fracture-pressure windows, wellbore stability, depleted formations, formation damage, and excessive casing strings, among others. The industry has responded by developing managed-pressure-drilling (MPD) technologies. The goal of MPD is precise management of the pressure in the entire annulus. In most instances, a rotating control head is used, diverting the mud returns through an adjustable choke. This closed system allows precise imposition of surface backpressure on the annulus and enables precise measurement of the mud-return rate. The use a rotating control device and choke in this way is very similar to a constant-bottomhole-pressure method of well control.
In September 2009, the SPE Drilling & Completions Applied Technology Workshop on Well Control was held in Rio de Janeiro, during which several companies involved in MPD made presentations on how their MPD technologies have enhanced well control. The closed system, which precisely measures surface pressures and mud-return rates, enables the detection of kicks (sometimes with less than 1 bbl of influx). Then, the mud-return rate is slowed to the prekick rate long enough to stop the influx and the well is killed, all without shutting in the well. In some cases, when a very small influx is detected, it is not even necessary to stop drilling.
The papers selected to be highlighted in this issue all detail unconventional well-control methods that have been used recently. On the basis of these papers and presentations at the Applied Technology Workshop, it appears that well control with MPD will quickly become conventional.
Well Control additional reading available at OnePetro: www.onepetro.org
IPTC 11970 Killing a Gas Well: Successful Implementation of Innovative Approaches in a Middle-Eastern Carbonate FieldA Field Case by S. Salehi, University of Calgary, et al.
SPE 121045 Prevention of Vertical Gas Flow in a Collapsed Well Using Silicate/Polymer/Urea Method by Istvan Lakatos, SPE, Reseach Institute of Applied Earth Sciences, University of Miskolc, and Geoengineering Research Group, Hungarian Academy of Science, Miskolc, Hungary, et al.