Exploring for natural gas is always very challenging job considering its high cost and high risk aspects
For exploring new reserve millions or tens of millions of dollars may be spent by a firm with the result being a “dry hole.” If the exploratory well indicate no possibility of economic accumulation of natural gas this is called dry hole. The average rate of success for exploration drilling is only 10% , so its very clear the probability of getting dry hole is 90% after huge investment and probability of discovery is 10%.
Exploration starts when a firm/company or group of firms acquires an onshore or offshore parcel on which to be drilled. sophisticated seismic imaging technologies are used to identify a target zone which has a higher probability of containing hydrocarbons. But environmental assessments are required to start drilling, this process might take two or more years in many areas .when they are obtained the firm engages a contractor to drill and one exploratory well is drilled .
If tests for exploratory well indicate a possible economic accumulation of natural gas this is known as a “discovery”. After the successful discovery one or more development wells are drilled to confirm the scope of the accumulation, this also provide additional properties of the underground rocks and fluids. Significant financial resources required for drill wells, design and construct a gas gathering and processing system
Development drilling: If drilling is performed into an already existing and producing pool of oil and/or gas, this is called Development drilling . The average rate of success for a development well is 85%.