Dutch operators struggling to fill spare pipeline capacity

Lasmo's Markham platform channels gas from this field and other satellites through the J3-K13 pipeline and then into WGT.

Dutch sector operators are having to contend with under-utilization of the country's three major North Sea trunklines. Worst is the situation for the Nogat line, which currently has at least 60% of its capacity idle.

This is followed by the Noordgastrans-port line (NGT), with 40-50% unexploited capacity. The situation is a little better at the Westgastransport (WGT), where vacant capacity has been decreased from 50 to 26% over the past two years.

In an attempt to rectify this situation, and stem falling production from the K, L and P blocks, most of the Dutch offshore exploration wells drilled this year and last have been targeting prospects close to installations in these blocks.

Nogat

Nogat's maximum capacity is 45.5 million cm/d, only 12.86 million cm/d of which was in use on average during 1995. However, following production increases from NAM's F3-FB and L5a platforms last fall, average gas throughput did climb again to just over 18 million cm/d in April.

The Nogat system comprises two sections: a 107 km, 24-in. piece between F3 and L2 and a 150 km, 36-in. stretch between L2 and the shore. Production comes from platforms operated by NAM and Elf Petroland.

The system was designed to accommodate double the amount of gas from the four production installations initially proposed, as further installations came onstream. The scenario was made attractive by a tariff structure in which rates for pipeline owners and third parties would be equal, and would even decrease as utilization of the system mounted.

Originally planned westward Nogat extensions into the D, E, J and K blocks never materialized. However, an extension to Nogat is finally in prospect following NAM's plan to develop its gas reserves in L9.

But the only other feasible extension option is a route from F3 heading north into the B and A blocks. NAM has a few promising gas finds in these areas and will start another concerted 18-month exploration drilling program shortly.

NGT

Capacity of the NGT system is 48 million cm/d. On average, 24.4 million cm/d headed through it last year compared with 23.6 million cm/d in 1994. A major contributor is NAM's Ameland Field, where production was boosted following installation of the AWG compression platform in 1994.

Elf Petroland, another major NGT supplier, saw its gas output from K6 and L7 blocks decrease last year to 5.85 million cm/d from 6.53 million cm/d the previous year. Production from its L4 block, however, increased. Compression for K6 is under way, with a Heerema-built module due to be installed next May.

Production figures from other platforms delivering gas through NGT were mostly stable, barring Unocal's L11-B platform where the figure dipped from 1.42 million cm/d to just 0.11 million cm/d this April.

WGT

WGT's maximum transport capacity of around 40mcm/d, only half of which was used in 1994. By April this year, however, usage had risen to 33.6mcm/d, almost 84% of total capacity.

The increase is down mainly to new production from Elf in K5 block that is transported through the J3-K13 pipeline, an extension of WGT installed in 1992 to serve Lasmo's Markham platform. The first K5 installation came on stream in 1994, with production averaging 5.86mcm/d last year. K5-EN/C, a new satellite installation in 1997, will further raise output.

In addition, Elf is expected to start developing fields in K4 block later this year or early next, depending on the outcome of appraisal drilling. At least two reservoirs in this geologically complex area are development candidates. Further supplies will tie in next year from Wintershall's new Windermere development on the UK side of the North Sea median line, and NAM may also connect its K1a gas find to Markham.

Total length of pipelines on the Dutch shelf is approximately 1,734km. No major new trunkline systems are planned. Apart from a possible northern extension of Nogat, the likeliest options for new lines would be east of Nogat and westwards into the E blocks. This area could, however, be reached also by extending NGT and/or WGT further north.

The Netherlands' State Supervision of Mines (SSM) has announced that rules will be issued this year or next concerning abandonment of offshore pipelines. There will not be an obligation to remove disused lines, but they will have to be cleaned sufficiently, with the options for total removal to be investigated before a decision is reached.

Pipelines in block K13 abandoned by Wintershall in 1989 have been cleaned internally and left on the sea bottom with open ends. According to an SSM spokesman, who undertakes regular inspections at the location, the lines have sunk into the sediments. First new abandonment candidates are Conoco's Kotter and Logger oil pipelines in blocks K18 and L16, where production will cease from the end of 1997. They have been put up for sale.

Source data for this report came from the Dutch Ministry of Economic Affairs and UK analysts Wood Mackenzie.

Copyright 1996 Offshore. All Rights Reserved.