Pushing the Frontier through Wellbore Strengthening

Abstract

Drilling Fluid Technology Making hole has become a more difficult and complex operation as operators move into untapped horizons, especially deepwater and unconventional fields. It is this increased difficulty that is driving a growing number of companies to invest millions of dollars in advanced materials that seek to make drilling wells easier. The technologies many are working on involve not mechanical systems, but advanced chemistry and physical science. Some are using nanoparticles and others are reworking older technologies by adding new substances, all in an effort to make the undrillable drillable. Those reaching for this prize include teams of university researchers, young technology startups, and established firms that are buying intellectual property from others so they can join the race. Different groups are designing drilling-fluid additives and other materials that they claim make unstable wellbore walls stronger by preventing and sealing fractures as the drill bit eats its way down to the pay zone. The importance of these wellbore-strengthening objectives is well understood by drillers who have suffered sudden losses of drilling fluids into the rock formation through fractures, which can lead to gas kicks and catastrophic blowouts, or those who have had to deal with stuck pipe because of a collapsed borehole. For petroleum engineers, preventing these problems with new technology means they can design simpler, cheaper, and safer wells with fewer casing strings. For the boardroom, wellbore strengthening means executives can promise better returns and higher flow rates to investors because large-diameter casing strings can be placed into the production zone. And for the industry in general, wellbore strengthening means wells that many consider too dangerous or too hard to drill may soon become tamed. Clay-Stabilizing Nanoparticles for Water-Based Drilling Fluids In April, downhole chemical technology provider Flotek Industries acquired water-based, drilling fluid-additive technology from ARC Drilling Fluids. Flotek hopes to use the technology, which it markets as Microsolutions, in areas where using oil-based drilling fluids have traditionally been the only option. Drilling fluids that use water as a base are far cheaper than oil-based fluids, making them more desirable, but oil is less reactive with many rock formations. Wellbore Strengthening: The Mechanical Option Before many of the new chemical and nanoparticle technologies for wellbore strengthening arrived to the marketplace, casing while drilling (CWD) was used for more than a decade to mechanically achieve the same end. Weatherford International and other service companies have developed multiple technologies for CWD, as well as the similar method of liner drilling (LD). With CWD, the casing is the drillstring, and with LD, the liner is the drillstring.