Tight gas

The gas is sealed in very impermeable and hard rocks, making their formation "tight".

These impermeable reservoirs which produce dry natural gas are also called "Tight Sand".

It is economic criteria (gas price, opex, capex, royalties and fiscal regime) which define this status and in many cases, as gas/oil prices rise then, projects that have been previously shelved become viable; improvements in technology or changes in available infrastructure may also rehabilitate otherwise stranded gas.

Hydraulic fracturing is one of the main methods to access the gas which requires breaking apart the rocks in the formation by pumping fracking fluids in to the wells.

Rock with permeabilities as little as one nanodarcy, reservoir stimulation may be economically productive with optimized spacing and completion of staged fractures to maximize yield concerning cost.