The advent of extended reach drilling (ERD) has increased the attainability of marginal reserves worldwide. Within the industry there are many “record breaking” feats that can be accomplished with innovative designs and new technology. However, some records hold priority over the others. Several recent projects show the extent to which operators can benefit from extended reach drilling operations.

In May of this year, Transocean Inc. and Maersk Oil Qatar both announced the drilling of the world’s longest extended reach well offshore Qatar. Using Transocean’s jackup GSF Rig 127, the well was drilled to a measured depth of 40,320 ft (12,289 m) with a horizontal section of 35,770 ft (10,902 m). The 36-day project exceeded the previous extended-reach record by a measured depth of 2,000 ft (610 m), which was set by a land rig at Sakhalin Island earlier this year.

The BD-04A well was completed with a 6.8-mile (10.9-km) horizontal section. The well also achieved an impressive record for longest reservoir contact. Using Schlumberger technology, the 81?2-in. 35,449-ft (10,812-m) horizontal section was drilled within 3 ft (.9 m) of the “sweet spot” in a reservoir target measuring 10 to 20 ft (3 to 6 m) thick. This is possibly the most important record to achieve because, at the end of the day, a well’s overall success is driven by contact between the reservoir and the well bore.

Also this year, Statoil completed a similar feat in when it completed drilling its Gulltopp well in the Northern North Sea Block 34/10 in 443 ft (135 m) of water. The operator chose to drill an extended reach well from its Gullfaks A platform rather than a subsea well, which could lower risk, but for a much higher investment.

Although it was expected to save the company around 70% compared to a subsea well, Gulltopp overran its original estimate costing US $177.3 million. The 6.2-km (10-km) well proved to be one of the most difficult projects in Statoil’s history. The well is now producing 22,000 b/d and paid back the operator’s investment in just two and a half months. Gulltopp now stands as the world’s longest well to be drilled from an offshore platform.

Extended reach drilling creates possibilities for smaller reserves as well. In Scotland, Caithness Petroleum is preparing to drill the country’s first ever land-based offshore well. It will be the first of two targeting the Lybster field, in the Inner Moray Firth, which is estimated to contain between 3 and 4 million bbl of oil.

Discovered 12 years ago, the prospect was considered too expensive to drill using offshore platforms at the time. Now with higher oil prices, Caithness has devised an ERD system that begins at a 100 ft-high (31-m) platform built onshore about 656 ft (200 m) from cliff edges. The well will then extend 2.2 miles (3.5 km) to the reservoir some 5,000 ft (1,525 m) below the sea. The operator hopes to reach the reservoir by September and believes the well could produce up to 1,000 b/d by the end of this year.

According to Caithness, drilling from a land base is cheaper, easier, and safer than offshore. With the success of this land-based system to reach underwater reserves, the overall impact on the environment could be lowered, leaving the marine environment virtually untouched. Caithness Petroleum is also pressing ahead with another discovery off Scotland. The Knockinnon field could be even bigger than the Lybster find and production would happen at another spot along the coastline.

Overall, extended reach drilling is improving the industry’s access to all types of reserves in virtually any type environment. The further application of high-performance drilling technology will help operators access more reservoirs and produce higher volumes from single wells. This development can lower environmental impact and eventually reduce overall costs. A low impact approach is what most operators and industry watchers want.

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