It is an appraisal well designed to follow-up the successful West Newton A-2 discovery well.
West Newton B-1 will be drilled down to a depth of around 2,000 metres over a period of six to ten weeks, the group said.
The project’s base case envisages some 146.4mln barrels of oil initially in place, with gas initially in place seen as 211.5bn cubic feet – whereas an ‘upside’ assessment sees 283mln barrels and 265bn cubic feet.
The well is also going to test the deeper Cadeby formation which is currently excluded from the above estimates, but, according to Union Jack, could significantly add to the value of the West Newton field.
West Newton is located close to existing infrastructure and is at the heart of the Zero Carbon Humber project.
The company noted that all operations are being conducted in accordance with coronavirus (COVID-19) related guidance and restrictions.
Sachin Oza, co-chief executive of Reabold Resources - a 56% economic stakeholder in the well - in a separate statement, said: "With the drilling of the West Newton B-1 well having commenced, we are a key step closer to proving up the significant resource base we believe we have at West Newton.”