Assessing the stratigraphic variations in geomechanical properties of the United Kingdom bowland shale using wireline and seismic data: How could these guide the placement of lateral wells?

Iain Anderson, Jingsheng Ma, Xiaoyang Wu, Dorrik Stow, John R. Underhill

Research output: Contribution to conferencePaper

Abstract

This work forms part of a study addressing the multi-scale heterogeneous and anisotropic rock properties of the Lower Carboniferous (Mississippian) Bowland Shale; the UK's most prospective shale-gas play. The specific focus of this work is to determine the geomechanical variability within the Preese Hall exploration well and, following a consideration of structural features in the basin, to consider the optimal position of productive zones for hydraulic fracturing. Positioning long-reach horizontal wells is key to the economic extraction of gas, but their placement requires an accurate understanding of the local geology, stress regime and structure. This is of importance in the case of the Bowland Shale because of several syn- and post-depositional tectonic events that have resulted in multi-scale and anisotropic variations in rock properties. Seismic, well and core data from the UK's first dedicated shale-gas exploration programme in northwest England have all been utilized for this study. Our workflow involves; (1) summarizing the structural elements of the Bowland Basin and framing the challenges these may pose to shale-gas drilling; (2) making mineralogical and textural-based observations using cores and wireline logs to generate mineralogy logs and then to calculate a mineral-based brittleness index along the well; (3) developing a geomechanical model using slowness logs to determine the breakdown stress along the well; (4) placing horizontal wells guided by the mineral-based brittleness index and breakdown stress. Our interpretations demonstrate that the study area is affected by the buried extension of the Ribblesdale Fold Belt that causes structural complexity that may restrict whether long-reaching horizontal wells can be confidently drilled. However, given the thickness of the Bowland Shale, a strategy of production by multiple, stacked lateral wells has been proposed. The mineralogical and geomechanical modelling presented herein suggests that several sites retain favorable properties for hydraulic fracturing. Two landing zones within the Upper Bowland Shale alone are suggested based on this work, but further investigation is required to assess the impact of small-scale elastic property variations in the shale to assess potential for well interference and optimizing well placement.

Original languageEnglish
DOIs
Publication statusPublished - 2019
EventSPE/AAPG/SEG Unconventional Resources Technology Conference 2019 - Denver, United States
Duration: 22 Jul 201924 Jul 2019

Conference

ConferenceSPE/AAPG/SEG Unconventional Resources Technology Conference 2019
Abbreviated titleURTC 2019
CountryUnited States
CityDenver
Period22/07/1924/07/19

ASJC Scopus subject areas

  • Renewable Energy, Sustainability and the Environment

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