Exploration and Appraisal
Geologists examine the local area and make an initial assessment about the likelihood of gas being underground.
They follow up with more in depth examinations, for example with a seismic survey that looks at the rocks underground. They figure out if the rocks are likely to contain gas and if so, how much.
If the signs all look good, the gas company will drill an exploration well. This well is used to find out if gas really is present, and if so, how far down.
If the exploration well results are promising, the gas company will drill an appraisal well. If not, the company will proceed immediately to decommissioning and rehabilitation.
An appraisal well is used to test the flow rate. It’s one thing to find gas underground, it’s another to extract it. If the gas flows too slowly the well would not be economically viable, because the cost of machinery, equipment and staff is high.
If the appraisal well results are promising, the gas company proceeds to developing the gas field.
If not, the gas company proceeds immediately to decommissioning and rehabilitation.