‘Suitable drilling sites and complex geology will constrain UK shale gas’

The biggest constraint on a UK shale gas industry could be finding land suitable for drilling sites, the Shale UK conference heard this afternoon. Complex geology would also limit how, and where, companies can drill.

Jeremy Lockett, subsurface manager with Centrica, said the result could be a few very large production pads with large numbers of wells.

Mr Lockett said shale gas companies in the US drilled very fast. “They whack out drills, day in and day out”, he said. “Anything that gets in the way kills the economics.”

The geology of US shale areas, such as the Marcellus, was boring, he said. “Boring is good. Anything that is complicated makes thing difficult. Within reason you can drill where you like.”

But in the UK large areas would be denied to companies. There would be, he said, at least a 200 metre exclusion zone around occupied properties.

“Surface access is always going to be a constraint in the UK and may be the key constraint”.

“Surface restrictions limit subsurface access”, he said. “Large areas will be inaccessible and this will mean poor acreage efficiency”.

Mr Lockett said that unlike the US, the Bowland shale area of northern England had lots of interesting geology. “From a development point of view you don’t want that. It’s going to be a challenge to drill.”

The Bowland basin had lots of fault of relative short length, he said.  “This means drilling horizontally is going to be interesting”.

“Complex geology will constrain the length of horizontal wells. Drilling across major faults in undesirable and you won’t want to frack into a fault zone.

“Areas will probably have major faults spaced 2-3km apart. Combine this with limited drill pad locations and that means that lateral well lengths will inevitably be limited at some locations. If wells need to follow maximum stress direction this may increase the constraint.”

He said the UK solution could be: “a few very large and operationally-efficient pads with tens of lateral wells.”

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