Reactivating production from a 45-year-old oil field is one of the challenges being tackled by Statoil in Venezuela.
LL-652 lies in Lake Maracaibo, which has been yielding crude for almost 80 years and currently accounts for two of the three million daily barrels of oil produced by the Latin American country.
Discovered in July 1948, this field came on stream five years later. It was taken over from state oil company Petrَleos de Venezuela SA in May 1998 by operator Chevron, with Statoil, Arco and Phillips Petroleum as partners.
These companies bring with them new technology which will allow daily output from LL-652 to be boosted from today's 8 000 barrels to around 115 000 barrels over five-seven years.
To meet this goal, pressure in the wells will be increased by large-scale water and gas injection.
The existing 100 wells currently producing are also to be supplemented by 300 more, reports Inge Myhre from Statoil, who is drilling superintendent for the field.
Recoverable reserves in LL-652 are put at more than 500 million barrels.
One of the biggest challenges in taking over an old field is the need to utilise existing equipment while developing new installations, reports reservoir manager Sjur Talstad.
Although LL-652 has produced for a long time, the project found itself short of basic data needed for effective resource management.
"We've been forced to shoot seismic and collect all information from the ground up," says sedimentologist and stratigrapher Donatella Mellere.
Lake Maracaibo also bears witness to the fact that oil production has been under way over a long period without much concern being shown for the environment.
The normal practice in these waters has been to install one platform per well. With 170 000 wells, the surface looks like a forest of derricks.
"This was once the world's largest freshwater reservoir," observes Mr Myhre. "Now it looks like a big graveyard."
The 13 210 square kilometre lake is six metres higher than the surrounding land at some points, and the locals have been forced to construct dikes against the water.
As oil is pumped out, the pores it once occupied have not been refilled with gas or water. The gas was simply flared off. So the lake bed is subsiding.
Some of the gas has been used for street lighting. In villages around the lake, gas pipes stick up from the ground and the naked flames are lit as darkness falls.
"You can see the water surface bubbling in some places as the gas rises from leaking pipes," says drilling inspector Rusty Fox in rig contractor Ensco.
Abandoned equipment and pipelines left lying on the bed of the lake, which is 15-40 metres deep, represent another environmental problem.
Perhaps the biggest pollution challenge is that most of the sewage from the surrounding communities goes directly into the lake. These sources include Maracaibo city, the second largest in Venezuela.
Meeting today's environmental standards will accordingly be one of the most important jobs for the companies involved in LL-652. Drill cuttings must be taken ashore and mixed with farm soil, for instance, and old scrap cleared from the seabed.
Gas can no longer be flared on the new field installations, but must either be injected back into the reservoir or exported. All leaks from existing structures on LL-652 have been repaired.
When the field was taken over, the partners implemented a base survey of the marine environment in the area. This will be repeated to see how environmental impacts develop.
"We've got to clean up first," says Mr Myhre. "Then we'll take it from there."
Source: Statoil.com
© 2000 Mena Report (www.menareport.com)
