Wellbore debris is something the oil industry has lived with a long time. An Aberdeen, Scotland company that specializes in the design and production of innovative cleaning sys tems believes it can fix the problem. The firm, SPS, points out that the cleanliness of the fluid at surface is not necessarily a good indication of the cleanliness of the wellbore.
The company has developed the Well Patroller™tool to perform a dual function in the pre-completion phase - performing a thorough cleaning action, and in the process, giving a validation of the effectiveness of the cleanup operation. The company cites a recent example where a Well Patroller™ trapped in excess of 20 kg of small steel particles from a wellbore after the failure of conventional means.
Apart from residual sludge, the product also has extracted pieces of steel, aluminium, brass, rubber, o-rings, cement, rubber hose, and hard band ing. SPS managing director Mark Carmichael believes that increasing numbers of operators concede that debris and sludge can significantly affect the NPT (non-productive time) for entire developments.
"Wellbore debris does not always interfere with running or setting a completion," he said. "But without a properly performed wellbore clean-up, running a completion is a bit like playing Russian roulette - most of the time, things go OK, but every once in a while, they don't."
Operation
The device is designed to be run in the cleanup string, usually in conjunction with other SPS cleaning tools like the Razor Back™ casing scraper, where it completes the clean-up by filtering debris from the annulus through a wire screen filter. The diverter cup/wiper removes a film of "gunk" from the ID of the casing. The cleanup operation is carried out in the normal way, pumping down through the device drillpipe mandrel and back up between the mandrel and the screen jacket. As the string is pulled, the diverter cup/ wiper diverts the annular fluid into the tool, where any debris is retained.
The system requires no balls or darts to be pumped down the drillpipe, and allows milling or drilling to take place with the tool in the string. It is operated very simply by pulling out of the hole, and is available in common casing and liner sizes.
Although performing a sophisticated task, the tool is simple to operate and is designed to be run as part of an integrated, one-trip pre-completion clean-up system which minimizes rig time.
Since 1991, SPS has introduced a number of specialized tools and methods. These designs and concepts have evolved into an integrated package which includes specialized circulating tools and mechanical cleaning tools, as well as the fluid cleaning and debris removal systems.
