Background for the audit
In the USA, ConocoPhillips has started using pressure-balance and casing drilling as new drilling methods where the differential between pore pressure and fracture pressure is marginal.
Such a pressure regime often prevails in high-temperature and high-pressure reservoirs and also increasingly in ageing Norwegian fields where pore pressure and rock tensions are changing due to production.
Purpose of the audit
The Petroleum Safety Authority Norway wants new technology to be used on the Norwegian shelf in order to increase safety and achieve maximum recovery of the resources.
We have noted that pressure-balanced and casing drilling is used on several fields in the USA with great success in terms of safety and economy when drilling in areas with little difference between pore pressure and fracture pressure.
We wanted to thoroughly review the company's plans.
Result of the audit
Our impression following the audit is that ConocoPhillips' plans for pressure-balanced drilling can be further assessed with a view towards application on Ekofisk.
We have asked the company to keep us continuously informed of their plans and the ongoing work to qualify pressure-balanced drilling as an applied drilling method.
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