Complete treatment

BJ Services entered the multizone single trip completion market in 2005, when it began designing its ComPlete Multizone Single Trip (MST) system in response to a pair of operator requests.

‘One operator had multiple reservoirs that were of similar pressure but separated by numerous shale layers,’ says David Walker, BJ’s director of completion technology. Still, the operator wanted to complete the zones cost-efficiently and still individually control production from each zone. A second operator had tight reservoirs and long zones in a deepwater project that needed large stimulation treatments to flow economically. ‘The required rates got to a point where they didn’t think they could effectively stimulate these long zones in a single treatment,’ Walker says.

In January this year, the company marked the 25th installation of the system. Fifteen of those applications have been in Indonesia, primarily with dry trees. The remaining uses have been in the Gulf of Mexico and offshore India in a mix of deepwater and shelf environments. Globally, the system has been used to treat over 100 zones.

The ComPlete MST system, which went commercial in 2007 and for which the company received a patent in July 2009, is a closed system that controls treating and production zone by zone, with tubing and a sleeve isolating each screen section, Walker notes. ‘So when you remove the service tool and you’re ready to run production, the wellbore is completely isolated,’ he says. ‘That’s the same feature that gives us the individual zone selectivity during production.’

Mechanical simplicity and reliability are also key in completing the installation successfully, Walker notes. Simple operations such as correctly positioning the service tools prior to treatment become more complex when treating multiple zones over long distances, he adds. The ComPlete MST system has one primary indicating point to prevent confusion about its location downhole. ‘Knowing where the tool is is critical to job success,’ Walker says.

BJ’s system carries out a process called pre-treatment isolation that involves running the isolation components into the wellbore along with the rest of the sand control equipment. ‘Once we install the system and set the packers, each zone in the well is isolated,’ Walker says. The ComPlete MST system gives fivezone selectivity. ‘The current system provides individual selectivity for all the zones. Right now that selectivity is mechanical,’ Walker says, noting that the process involves running a shifting tool to mechanically open the zones as needed. In general, time savings is considerable, where working on five zones before would take a week and a half, it now takes half that or less, with pumping occupying most of that time, Walker says.

BJ’s 95/8in x 33/4in ComPlete MST system can handle frac or gravel packs pumped at 40b/min while its 95/8in x 51/8in system can handle rates to 50b/min.

‘The next features to be incorporated into this system will be the integration of the intelligent well systems,’ Walker says. Included in this, he notes, is the capability for remote data acquisition systems. ‘That’s what we’ve been requested by the operators to work on for the future.’ OE

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