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Contractors were brought in early and Once the casing was in place, Shell

Drilling

The Doo Sung rig was integrated into the team. In addition, the then used pressurized mud cap drilling. contracted in and brought specialist teams were tasked with making This is a variation of managed pres- to Shell standards to operations simpler. The subsurface team, surized drilling, that involves drilling deliver the campaign. Doo for example, only asked the wells team to with no returns to surface and where an

Sung is Korea’s only semi- acquire data that was necessary annulus fuid column, assisted submersible drilling unit, for the evaluation of the well. by surface pressure, is main- built in 1984 by Daewoo

This campaign approach tained above a formation that is

Shipbuilding Co., and owned allowed the teams to narrow capable of accepting fuid and by KNOC. their scope and follow fit-for- cuttings.

Photo from KNOC.

purpose standardized well Tan explains that in some designs, while questioning con- formations Karst losses can be using Korea National Oil ventional drilling approaches. encountered—a risk associated

Company’s Doo Sung semi- “We allowed the wells team to with carbonate reservoirs. This

Ivan Tan, Shell.

submersible drilling rig. The design a well that was fit for can result in drilling fuids Photo from Shell. second, fve-well campaign purpose,” Tan says. “Everything dropping out into the reservoir, started in March this year, was challenged and we did not accept creating a risk that hydrocarbons will using a jackup drilling rig. the norm. Every conventional drilling escape. In the past, as soon as drilling “Essentially, we had to drill approach was challenged and novel well teams suspect they have encountered low-cost exploration wells,” designs devised.” Karst losses, they have to abandon the says Ivan Tan, who until Two key technologies were deployed— well and try to drill another nearby. recently was general man- pressurized mud cap drilling, which Using a mud cap enables the drilling ager, well operations for Shell had been developed for carbonates in team to keep a cap of mud in place so

Malaysia. “Shell has been oper- Malaysia, and casing while drilling tech- hydrocarbons don’t escape during drill- ating in Malaysia for more than nology (CWD). ing. Getting the right balance of pressure 100 years. In this exploration “While both have been around in the is key.

The program’s campaign approach, campaign, we were targeting the industry for a while, we combined the with a minimum of 5-6 wells in each remaining reserves that existed two and made it work for us,” Tan said.

campaign, also meant learnings could in smaller deposits in our The CWD is used frst, using a 9-5/8” be incorporated. “We saw the learn- carbonate felds. To do this, we casing size, which enabled Shell to drill ing come through in 2-3 wells, which had to fnd novel and innova- and case at the same time. The well meant we could build on success after tive ways to drill the wells at a concepts on the campaign were designed success, using the same team and same lower cost.” around Shell’s CWD concept. contractors and equipment,” Tan said.

The Central Luconia res- During the campaign that began in

Drilling optimization “So we had economies of scale and ervoirs are mostly carbonate 2012, the team set a record for the longest practice makes perfect.” and what is left are smaller casing while drilling job. In May 2013,

There was also a “boots on the and more distributed volumes. the 9-5/8” casing was drilled to 6255ft ground” ethos, to safely manage the

About 15-20 targets were identifed, but measured depth, or 6170ft true vertical operation and a risk-sharing ethos to by conventional methods were deemed depth subsea. offshore Sarawak contracts, so goals were aligned. uneconomic or, as with seismic, not “It may not be now, but at the time we worth the cost due to their sizes. knew we were leading the pack in casing Tan says the 50% cost reduction was “The strategy was to drill as many while drilling,” Tan said. achieved in the frst campaign. The wells into these distributed pinnacles,” frm has assessed its costs by compar-

Shell’s Malaysian drilling cost

Tan says. “But to do that we had to ing benchmark data held by Rushmore – cost comparison.

reduce costs. The target was simple: to Reviews. This data was highlighted cut the well costs by 50%.” by Shell at its management team day

The concept was initiated in about (see graphic). This put Shell Malaysia 2010, and, after signing the PSC agree- in the best in class category (top 5%), ment in 2012, the frst tranche of explora- based on the frst six wells drilled in the tion wells was drilled in late 2012. campaign. “There were a number of things that “These are probably the cheapest underpinned the whole process,” Tan subsea exploration wells ever drilled by said. “Good prospect selection and an operator worldwide on a normalized well design, contracting, and procure- basis, according to Rushmore data,” Tan ment strategies, and taking a campaign said.

As the PSC operator to PETRONAS, approach to the program were impor-

Shell is the largest gas producer in tant elements in the campaign. Critical

Malaysia, accounting for 60% of the success factors included a lot of early country’s gas production. Some 90% of integration, especially between the sub- the gas produced is earmarked for surface and the wells teams, and sitting the PETRONAS LNG complex in everyone around the same table, drawing 1Q 2014 results image from Shell.

Bintulu. on experience together.” oedigital.com July 2014 | OE 39 038_OE0714_Drilling_elaine.indd 39 6/20/14 2:58 PM