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? eld life.

The key challenges on Mariner are the viscosity of the oil, which requires intensive drilling and therefore com- plex well placing, as well as arti? cial

Drilling lift technologies, and shallow reser- voirs, which make the intensive drilling all the more challenging.

In total, Statoil has identi? ed some

Factory drilling 147 reservoir targets, to be reached using lateral wells, and some multilaterals,

Statoil’s plan is a production, drilling

As with a number of other heavy oil- from a total 98 wells from the surface.

Drilling on Statoil’s Mariner ? elds in the area, and despite a string of With 50 slots on the Mariner platform, and living quarters platform, currently will be a mega project – development studies and concepts, the that means many wells will have to be being built in Korea, on a steel jacket, ? eld was left undeveloped because of the side-tracked.

being completed in Spain, with a ? oating but Statoil is looking dif? culties around extracting heavy oil. “Statoil hasn’t done anything like storage unit, supported by a jackup, with to lighten the load startup planned for 2017 and a 30+ year

These dif? culties are being overcome. this, with such a large drilling and well in ways that could only be done on such a large project. Elaine Maslin found out more.

hen drilling starts on the

Mariner heavy oil ? eld, it

W will become one of the big- gest offshore factories constructed in the

North Sea.

In the ? rst production phase, at least 130 well targets are to be drilled over 11 years, at a rate of about 10-12 per year in the initial years, from a platform rig and jackup alongside, supported by an intervention and completion unit.

It’s going to be quite some task, cost- ing more than US$7 billion in total.

But, because of the scale of the task, operator Statoil has been able to make some upfront decisions on its approach to drilling and completions on the ? eld, from which it stands to reap bene? ts during the ? eld’s 30+ year long life.

The ? eld

Mariner, a heavy oil ? eld in relatively shallow Maureen and Heimdal sands, was discovered by Union Oil on the East

Shetland Platform in Block 9/11, 150km 1981. east of the Shetland Islands, in

Some ? ve seismic surveys have been shot over the license since it was ? rst awarded in 1980, and 18 wells have been drilled by four different operators (OE:

March 2015), proving up an estimated 1 billion boe in place, and 250 MMbbl recoverable oil, ranging from 67-508 centipoise viscosity.

The Mariner ? eld concept artists’ illustration. Images from Statoil.

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