In situ crustal stress in the United Kingdom from borehole breakouts

Evans, C. J.; Brereton, N. R.

doi:10.1144/gsl.sp.1990.048.01.27

Cited by 24 publications

(22 citation statements)

References 16 publications

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“…The predominant NW trend of the main Carboniferous joint sets is coincident with the present day maximum horizontal stress direction (145/325 o , Evans & Brereton 1990). Rogers (2003) predicted that the stress-induced fracture permeability is likely to be higher along this trend in the current UK stress field.…”

Section: Porosity Permeability and Fracture Porositymentioning

confidence: 85%

UK data and analysis for shale gas prospectivity

Smith

Turner

Williams

2010

PGC

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Organic-rich shale may contains significant amounts of gas held within fractures and micro-pores and adsorbed onto organic matter. In the US shale gas extracted from regionally extensive units such as the Barnett Shale currently accounts for ~6% of gas production. Shale gas prospectivity is controlled by the amount and type of organic matter held in the shale, thermal maturity, burial history, microporosity and fracture spacing and orientation.The main UK organic-rich shale sequences have been mapped at the surface and in the subsurface using a combination of outcrop, well and seismic data. Potential targets range in age from Cambrian to the late Jurassic: younger shales have been excluded because they have not reached the gas window, but they may possess a biogenic gas play. A GIS showing the distribution of potential reservoir units has been combined with information on hydrocarbon shows, thermal maturity, fracture orientation, gas composition and isotope data to identify potentially prospective areas for shale gas in the UK. These include Lower Palaeozoic shale basins on the Midland Microcraton, Mississippian shales in the Pennine Basin and Pennsylvanian shales in the Stainmore and Northumberland basin system.

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Section: Porosity Permeability and Fracture Porositymentioning

confidence: 85%

UK data and analysis for shale gas prospectivity

Smith

Turner

Williams

2010

PGC

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“…This suggests that the stress regime differs from the dominantly strike-slip state of stress observed in adjacent areas in the onshore part of the UK (Evans & Brereton 1990;Baptie 2010), and which is also thought to be prevalent in the basement rocks beneath the UK SNS. which the well was drilled, and parallel to the orientation of crestal extensional faults (Williams et al 2014).…”

Section: Stress Detachment Above Evaporitesmentioning

confidence: 87%

In-situ stress orientations in the UK Southern North Sea: Regional trends, deviations and detachment of the post-Zechstein stress field

Williams

Fellgett

Kingdon

et al. 2015

Marine and Petroleum Geology

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The orientation of the maximum horizontal compressive stress (S Hmax ) in the UK Southern North Sea has been determined using data derived from borehole breakout analysis of four-arm caliper logs.The results agree with existing stress models for NW Europe, confirming that horizontal stresses in the region have an approximately NW-SE orientation of S Hmax . This is interpreted as being a result of plate boundary convergence. Local deviations in the horizontal stress orientations are observed spatially and also vertically within some wells. Some of these deviations are attributed to rotations of the stress field adjacent to faults or between different fault blocks. The data also suggest detachment of the stress regime in the post-Permian cover rocks, caused by the presence of a thick underlying Permian-aged evaporite sequence and associated halokinesis. Despite the generally low scoring of the stress measurements when compared with the quality ranking scheme proposed by the World Stress Map project, the consistent orientation of the stress trajectories suggests that these data are reliably indicative of regional stress orientations. Analyses of borehole resistivity image logs have been used to verify the calculated stress orientations in some wells. These image logs validate some measurements whilst highlighting a number of deficiencies in the use of four-arm caliper data to characterise borehole breakouts. From the available data it is difficult to unambiguously define the nature of variations from the mean stress orientations observed. Further analysis of image log data over greater depth intervals is therefore required in order to investigate more fully the effects of stress rotations near faults and apparent stress detachment above saltcored anticlinal structures.

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“…England (e.g., Evans and Brereton, 1990;Cartwright, 1997;Baptie, 2010). It has long been known that the differential stress in Britain is relatively high; for example, its magnitude and orientation have influenced the design of coal mines (Cartwright, 1997).…”

Section: State Of Stressmentioning

confidence: 99%

The importance of characterizing uncertainty in controversial geoscience applications: induced seismicity associated with hydraulic fracturing for shale gas in northwest England

Westaway

2016

Proceedings of the Geologists' Association

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Westaway, R. (2016) The importance of characterizing uncertainty in controversial geoscience applications: induced seismicity associated with hydraulic fracturing for shale gas in northwest England. Proceedings of the Geologists' Association, 127(1), pp. 1-17.There may be differences between this version and the published version. You are advised to consult the publisher's version if you wish to cite from it.http://eprints.gla.ac.uk/119683/ AbstractFracking of the Preese Hall-1 well in 2011 induced microseismicity that was strong enough to be felt.This occurrence of 'nuisance' microearthquakes, unexpected at the time, was a major factor resulting in adverse public opinion against shale gas in the UK and was thus of significant political importance. Despite this, and notwithstanding the technical importance of this instance of induced seismicity for informing future shale gas projects, it has received little integrated study;contradictory results have indeed been reported in analyses that lack integration. This instance therefore provides a case study to illustrate how a small but significant multi-disciplinary geoscience dataset may be put to best use, including how best to quantify uncertainties in key parameters, which may themselves be relatively poorly quantified but whose values may significantly affect the ability to understand the occurrence of induced seismicity. The best-recorded event in this induced microearthquake sequence (at 08:12 on 2 August 2011) is thus assigned an epicentre circa British National Grid reference SD 377 358, south of the Preese Hall-1 wellhead, a focal depth of ~2.5 km, and a focal mechanism with strike 030°, dip 75°, and rake -20°, this NNE-striking nodal plane being the inferred fault plane. Like other parts of Britain, this locality exhibits high differential stress, with maximum and minimum principal stresses roughly north-south and east-west. This instance indeed fits an emerging trend of the occurrence of relatively large induced earthquakes in localities with high differential stress; such an association was predicted many years ago on the basis of experimental rock mechanics data, so observational confirmation might well have been anticipated and should thus not have been unexpected. Many steep faults, striking NNE-SSW or NE-SW, mostlyCarboniferous-age normal faults, are present; the stress field is favourably oriented for their leftlateral reactivation, southward leakage of fracking fluid into one such fault having presumably caused the induced seismicity. Given the pervasive presence of similarly-oriented faults, future occurrences of similar induced seismicity should be planned for; they pose a significant technical challenge to any future UK shale-gas industry.

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In situ crustal stress in the United Kingdom from borehole breakouts

Abstract: Until recently very little in situ stress data have been available from the UK

Cited by 24 publications

References 16 publications

UK data and analysis for shale gas prospectivity

UK data and analysis for shale gas prospectivity

In-situ stress orientations in the UK Southern North Sea: Regional trends, deviations and detachment of the post-Zechstein stress field

The importance of characterizing uncertainty in controversial geoscience applications: induced seismicity associated with hydraulic fracturing for shale gas in northwest England

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