Models focus on quick drilling, well evaluation in mature areas

Amerada Hess' earlier discovery in the Outer Moray Firth, named Rochelle, was very close to the Finder model, derived from Phase 1 of the Crine "Doubling the Values of Wells" workgroup. A previous discovery in the same region, Goldeneye, was also close to the model, except that coring was performed.

Rochelle is an oil and gas accumulation in Early Cretaceous Kopervik sands, within tieback distance of Amerada's semisubmersible platform AH001, which currently produces the Ivanhoe-Rob/Roy and Renee/Rubie fields. Drilling, performed by the Stena Spey, was completed ahead of schedule this April. The reservoir target depth of 10,500 ft was reached in 12.2 days from spud.

These results involved an application of industry best practice in the form of an aggressive, slimmed-down casing design and formation evaluation program that allowed the choice of a motor above the bit to reduce downhole vibration while drilling through chalk.

This helped Amerada to keep its FEWD (formation evaluation while drilling) logging tools running, while also achieving a high rate of penetration. Previously, the company had experienced some tool failures drilling through chalk. "This time, we managed to acquire information across the zones of interest," said Craig McGregor, Amerada's Well Operations Manager. "This was also the fastest we've ever drilled in depths greater than 10,000 ft."

Finder approach

Amerada's European Exploration Director Jan Evensen, commenting on the significance of the Finder approach, said, "As the UKCS becomes more mature, the size of prospects will inevitably decline. Our ability to drill minimum-cost Finder wells, such as that on Rochelle, opens up the possibility of drilling a whole tranche of opportunities which would otherwise be sub-commercial."

Amerada is aiming for a 50% cost savings on UKCS wells and also accelerated access to small accumulations. The key to this strategy is a new in-house program called "To the Limit" or T2L. The program is derived from a scheme pioneered by Woodside on Australia's North West Shelf in 1994, called "Technical Limit."

"The T2L concept basically asks: 'How quickly can we deliver a given design?'" says Amerada's Well Superintendent Dave Taylor. "It is the relentless pursuit of excellence and encourages personnel to challenge operations that have hitherto been considered unavoidable, part of the cost of doing business."

Questioning notions

The new approach requires staff at all levels to question pre-conceived notions, then put forward innovations to aid the drilling process - and not to feel slighted if their views aren't heeded immediately. Risks are assessed before any changes are incorporated into the detailed plans.

"We've also created an environment where people can put their hand up and say, 'There's a better way of doing this,'" Taylor points out. "And that's OK, even if it implies that there's been an error. We've trained nearly 250 people in this new enabling environment. So, for example, if we drill a well in 12 days, we get everyone involved in 'let's figure out how we can do even better next time.'"

Ideas that have already been implemented, and paid off, include:

• Making greater use of pre-assembled bottom hole assemblies with cement wipers plugs pre-installed in wellhead and casing running tools
• Switching to shipping pre-hydrated bentonite mud, as the on-board dehydration process was slowing down parallel drilling activities
• Without compromising safety, establishing drills for blowout preventers that prove the system's integrity, boost crew training, and allow the previous regime of elaborate testing to be made fit-for-purpose.

Amerada extended T2L to development wells in the northern sector of the UKCS in June. This has extended the methodology into completion activities. It has included its main service providers from the start, and extending the concept to its contractual arrangements, under a program called Procurement Support for T2L.

"There is a perception among service companies that improvements from these endeavors only benefit the operator," Taylor says. "But if we can involve them to help us drill even cheaper wells, we can access smaller accumulations and more marginal exploration prospects, which means more activity, which in turn helps the supply industry."