While not as glamorous as new discoveries, the attractiveness of mature fields is growing as they can provide operators with quick access to low-risk resources. With 70% of the hydrocarbon liquids produced in the world today coming from fields that have been in operation more than 20 years, focus has shifted onto developing these fields with the goal of producing more of the remaining resources.

Take, for example, the decision to expand the supergiant Tengiz oil field in Kazakhstan. Production of the sixth largest field in the world started in 1993. In July Chevron Corp. affiliate Tengizchevroil, in a joint venture with Exxon Mobil Corp., KazMunayGas and LukArco, announced its decision to proceed with a $36.8 billion future growth and wellhead pressure management project. The plan calls for, upon completion, production at the field to increase by 260,000 bbl/d to 850,000 bbl/d through the use of sour gas injection technology developed and proven during the field’s previous expansion in 2008.

In some cases, the best use of a maturing asset is to give it a new purpose. Statoil’s Heimdal Field, celebrating its 30th anniversary this year, is one example of this. The first well in the field was drilled between July and December 1972 and proved to have both gas and condensate reserves. At the time of first production in December 1985, the Heimdal platform was the largest steel jacket platform on the Norwegian Continental Shelf.

Declining production after a decade of steady production led to a transition from production to processing. In January 1999 approval was given for the Heimdal Gas Center. The center serves as a hub for the processing and distribution of gas. According to Statoil, gas from Heimdal is processed together with gas from the Huldra and Vale fields. Heimdal receives gas from the Oseberg Field Center through the Oseberg Gas Transport system. Gas is exported via the Vesterled and Statpipe pipeline after processing.

In this report, E&P delves into a new casing exit service that uses real-time information to increase efficiency. The report also looks into how Maersk Oil has breathed new life into Denmark’s oldest producing field at its multiplatform Dan Field complex in the Danish North Sea sector, how exploration in mature basins has led to new discoveries and how an internal liner system can be used as an alternative for subsea pipeline replacement.

Read each cover story:

Casing exit service delivers significant reduction in rig time

Maersk enjoys bravura performance on Bravo

Diamonds in the rough

Liner offers alternative to replacement of subsea pipelines