Uplift and Erosion Onshore UK - Implications For Shale Oil and Gas Potential

Abstract

Recent announcements in the UK press and further discussions online have suggested that the significant uplift and erosion history of the UK since the Early Tertiary has brought into question the unconventional resource potential of the onshore UK. However, recent 3D basin and petroleum systems modeling studies at Imperial College have strongly suggested that the uplift and erosion is in fact likely to be key to the future success of Shale Oil & Gas exploitation in the UK. Potential source rocks in two key basins have been evaluated: These are the Carboniferous Bowland Shale of the Gainsborough Trough of northern England and the Jurassic Kimmeridge and Oxford clays in the Weald Basin of Southern England. Both of these basins are the location of existing conventional oil & gas fields indicating two working petroleum systems despite the uplift events. The petroleum systems models have been populated by analytical data from cuttings and core samples taken from these source rocks. The cores and cuttings have been analyzed for geochemistry, mineralogy and petrology and the results combined with wireline log data, 3D and 2D seismic interpretation to provide the input for the 3D models. Importantly, the results of the modeling show that the uplift and subsequent erosion have enhanced the potential of the two basins in several ways, rather than downgrading it. Firstly, uplift brings oil & gas mature source rocks within easy reach of the drill bit. The second positive implication is that uplift and subsequent erosion has partly preserved the pressures achieved in the shales during burial and brought these to shallower depths where they are effectively over‐pressured, providing energy for production. Furthermore, the uplift and depressurization of brittle formations interbedded with the shales is thought to have induced natural hydraulic fractures in the rock, which potentially allows for commercial production rates without the requirement for extensive fracking activities. Two key wells will be drilled in the Gainsborough Trough in 2019, which will importantly calibrate the results of the modeling.

AAPG Datapages/Search and Discovery Article #90349 © 2019 AAPG Hedberg Conference, The Evolution of Petroleum Systems Analysis: Changing of the Guard from Late Mature Experts to Peak Generating Staff, Houston, Texas, March 4-6, 2019