Potential Environmental Risks from Surface Infrastructure Associated with Shale Gas Extraction by Hydraulic Fracturing

Abstract

The possible development of a shale gas industry within England has raised concerns with regards to the potential impacts of surface infrastructure on the natural environment. The aim of this thesis was to assess and quantify some of these concerns, specifically those related to surface footprint, the potential for spills, and the possible long term implications a shale industry may bring.

The carrying capacity of the licence blocks over the Bowland Shale in northern England has been assessed using a variation on the Buffon’s needle approach, with the average carrying capacity for a licence block found to be 26%. The carrying capacity of the land surface, as predicted by this approach, would limit the technically recoverable gas reserves for the Bowland Basin to 2.21 x 10^11 m3.

If the average license block was developed to its full potential, a lateral length of 1300 m would be the most probable optimal lateral length required to maximise recoverable gas reserves. This lateral length would generate an average carrying capacity of 12 wells per licence block, generating a technically recoverable gas reserve of 1200 x 10^8 m3.

Using data from the US and comparator industries within the UK an estimated number of spills both onsite and offsite has been quantified. Based on data from the Texas Railroad Commission, a UK shale industry consisting of well pads with 10 laterals would likely experience a spill for every 16 well pads developed. Using milk tanker data, a well pad of 10 laterals would likely experience a spill for every 19 well pads developed.

From evaluating aerial imaging and performing fieldwork at conventional oil and gas well sites within the UK, surface and subsurface remediation of abandoned well sites was found to be insufficient.

Largely the results from this thesis indicate that the surface impacts of a shale industry are not unique and that existing industries pose similar risks. By assessing comparator industries mitigation strategies have been suggested to manage and mitigate against potential future concerns.