Introduction

Unconventional hydrocarbon reservoirs are loosely defined as those that cannot be produced with conventional techniques, and sophisticated methods including multistage hydraulic fracturing and horizontal drilling are used to produce gas and/or oil from these reservoirs. In general, the volume of gas present in different geological reservoirs has been found to increase from conventional reservoirs to unconventional Coal Bed Methane systems to tight sand and shale gas systems to gas hydrates, although more abundant gas resources bring in more significant environmental integrity into play.