In many conventional natural gas reservoirs, a few vertical wells every 2.5 square kilometres (around one square mile) are enough to produce the resources available. In contrast, tight and shale gas does not flow easily and resources are often spread over a much larger area, making it harder to access.
We drill wells in different directions from a central location that penetrate the reservoir vertically, often in an S-shape, or horizontally. This limits the number of drilling locations – known as well pads – and reduces our overall surface impact.
Well pads can be spaced up to five kilometres (three miles) apart. Some accommodate up to 50 wells or more. Mobile drilling rigs allow us to avoid dismantling and reassembling drilling equipment at each pad, making the process quicker and saving resources.
Wells can stretch several kilometres underground. For example, in Groundbirch, Canada, we drilled a well 6.25km (3.88 miles) long. In Changbei, China, we drilled an extensive network of wells up to two kilometres (1.2 miles) long to open up a much greater area for gas extraction. This increased potential production as much as ten times compared with conventional techniques.