An assessment of the footprint and carrying capacity of oil and gas well sites: The implications for limiting hydrocarbon reserves

We estimate the likely physical footprint of well pads if shale gas or oil developments were to go forward in Europe and used these estimates to understand their impact upon existing infrastructure (e.g. roads, buildings), the carrying capacity of the environment, and how the proportion of extractable resources maybe limited. Using visual imagery, we calculate the average conventional well site footprints to be 10,800 m² in the UK, 44,600 m² in The Netherlands and 3000 m² in Poland. The average area per well is 541 m²/well in the UK, 6370 m²/well in The Netherlands, and 2870 m²/well in Poland. Average access road lengths are 230 m in the UK, 310 m in The Netherlands and 250 m in Poland. To assess the carrying capacity of the land surface, well pads of the average footprint, with recommended setbacks, were placed randomly into the licensed blocks covering the Bowland Shale, UK. The extent to which they interacted or disrupted existing infrastructure was then assessed. For the UK, the direct footprint would have a 33% probability of interacting with immovable infrastructure, but this would rise to 73% if a 152 m setback was used, and 91% for a 609 m setback. The minimum setbacks from a currently producing well in the UK were calculated to be 21 m and 46 m from a non-residential and residential property respectively, with mean setbacks of 329 m and 447 m, respectively. When the surface and sub-surface footprints were considered, the carrying capacity within the licensed blocks was between 5 and 42%, with a mean of 26%. Using previously predicted technically recoverable reserves of 8.5 × 10¹¹ m³ for the Bowland Basin and a recovery factor of 26%, the likely maximum accessible gas reserves would be limited by the surface carrying capacity to 2.21 × 10¹¹ m³.