Abstract
One of the biggest ongoing challenges to the successful production of many natural gas reserves is the ability to improve drilling efficiency. In many of these applications, in order to drill the interval safely, it is necessary to drill through gas producing formations using high mud weight. As is well known in the industry, drilling with high mud weight poses significant challenges to drilling efficiency. Generally speaking, high mud weight equates to high solids content in the mud, and slow ROP for the drill bit, which means high hours to drill the section and frequent bit trips. Further to that, high hours and high solids equate to wear and erosion problems with bits and downhole equipment, leading to higher costs.
A new line of steel bodied drill bits has recently been introduced that has shown dramatic improvements in drilling efficiency in Western Canadian foothills natural gas applications. The hydraulic configuration (blade shape & height, void volume, junk slot area, nozzle orientation and TFA flexibility) of the drill bit is of paramount importance in applications with high mud weight. Bit balling is very common in these types of applications, and is very detrimental to drilling efficiency. The ability to utilize a steel body, and to protect it from the typical erosion and wear that is seen in high solid environments, is critical to maximizing hydraulic performance.
The new technology developed for these drill bits allows higher ROP in high mud weight applications, increased mechanical efficiency during the drilling process, and greatly enhanced wear / erosion resistance. Runs have been recorded in intervals with ≥ 1750 kg/m3 mud weight and > 85 cP viscosity showing dramatic increases in ROP, with absolutely no erosive wear to the body of the bit, even after drilling for ~ 160 hours. This significant increase in ROP is a major breakthrough as less time spent in the hole means less wear and erosion on all downhole components.
