More dialogue over CINGSA pressure

When Cook Inlet Natural Gas Storage Alaska, or CINGSA, finished topping up its Kenai Peninsula storage reservoir in November, ready to support high utility gas demand in the coming winter, the company discovered that the reservoir pressure exceeded the permitted maximum for the facility. The company notified state authorities of the discrepancy and subsequently received a notice of violation from the Alaska Oil and Gas Conservation Commission. There is still a continuing dialogue over exactly how the pressure ended up being too high.

On Dec. 26 the commission sent a letter to CINGSA requesting further clarification of how the company had failed to spot the approaching excess pressure, even although CINGSA said that it had been using one of the facility’s wells to monitor the reservoir pressure as the reservoir filled.

In a Jan. 30 response CINGSA confirmed that it had been monitoring the pressure using one of the wells. But as the company watched the transient pressure, as gas was injected underground, the company believed that once the pressure stabilized across the reservoir, it was unlikely that the pressure would exceed the permitted maximum.

CINGSA had previously experienced unexpectedly high pressures during some earlier shut-in tests and had attributed these pressures to some technical issues associated with re-pressurizing the reservoir, a depleted gas reservoir in an old gas field. And, given the lack of a sufficient operational track record for the relatively new CINGSA facility, it was impossible to tell whether the high pressures represented transient pressures resulting from that reservoir refilling, or whether the well had encountered a pocket of high-pressure gas from the original gas field.

CINGSA has been conducting some reservoir modeling to try to nail down the precise cause of the pressure anomalies, the company said.

The company has undertaken to adopt a more conservative approach to its pressure management in the future.

—Alan Bailey