Ramco Energy Plc, operator of the Seven Heads gas field in the Celtic Sea, says wellhead pressures have declined. The average production rate from the field over the past 25 days of uninterrupted production was 44.4 MMcf/d.
The technical team reviewing the Seven Heads reservoir has not completed its work, but believes it is likely that water that has condensed from the gas, plus a small amount of formation water, are building up in one or more of the well bores, thereby masking reservoir pressures and aggravating the decline in production.
Ramco has consulted with its partners and Marathon, and is developing plans to embark on a diagnostic "blow-down" program, which will involve all five of the Seven Heads wells being shut in. A temporary connection to the compressors on Marathon's Kinsale A platform will then be used to reduce the pressure in the pipeline connecting Seven Heads to the platform. Once this has been done, the Seven Heads wells will be re-opened. This should result in a surge of production that will remove any water that has built up in the well bores. The blow-down program should take five days to complete.
The data obtained during this process should allow an improved measurement of reservoir pressures, and will be invaluable in helping to determine the future deliverability and recoverable reserves of the field, the company says. It is anticipated that this process will at least increase production rates and may be repeated periodically to clear water from the well bores until a permanent solution can be assessed.
Longer term plans will be based on the data gained from the blow-down process and on final technical assessments. Ramco is also investigating a permanent arrangement to access one of the three compressors already in place on the Kinsale platform, which could be adapted to facilitate Seven Heads gas flows.
The Seven Heads partners are Ramco 86.5%, Island Petroleum Developments Ltd. 12.5%, and Sunningdale Oils (Ireland) Ltd. 1%.