Tango 123 is obviously sadly deluded. Why on earth would NS oil be a national security question? This is something more akin to the response to the GMB union. Our coal industry has been allowed to go into decline because cheaper sources are available. Amongst non Third-world countries which are in the top-ten oil exporters are Norway, USA and Canada as well as our former colony of Nigeria with which we have a close commercial relationship. As for reducing the rate of tax to 10% that's laughable. Oil and gas exploration already attracts research and development allowances which allow for 100% write off of the expenditure for tax purposes.
Many NS oil fields are already reaching the end of their viability and the oil companies only keep them operating on a "use it or lose it" basis because of the huge costs of decommissioning them.
The Government is already making a loss from North Sea oil and gas because revenues are presently more than cancelled out by repayments to producers, leaving the Government's North Sea accounts £39million in the red between April and September of 2015, according to HMRC figures, which is thought to be the first time the UK has recorded a loss over a six month period since the North Sea oil industry became established 40 years ago.