Tight gas is the name given to the unconventional natural gas because it is trapped in a very tight underground hard rock, or sandstone or limestone formation that is unusually impermeable and non-porous called tight sand.
In a conventional natural gas deposit, once drilled, the gas can usually be extracted quite readily, and easily.
A great deal more effort has to be put into extracting gas from a tight formation.
Several techniques exist to extract tight gas, such as fracturing and acidizing.
However, these fracturing techniques are also very costly because tight gas need a lot of wells to develop it as the flow rates of individual wells are quite low.
Compared with shale gas, the tight gas requests a complex optimization of vertical drilling and horizontal drilling in combination with the fracturing operations.
As shale gas, the tight gas requires a lot of water which in some regions like Middle-East imposes to collect the waste water and to treat it.