Inorganic geochemistry as a tool to improve the understanding of shale gas plays

Abstract

The rapid increase in interest in exploring shale units for shale oil and gas has highlighted the need to develop a thorough understanding of shale units. Not only does possessing a detailed understanding of shale stratigraphy enable accurate volume calculations to be undertaken, but, knowing the mineralogical composition of shale can provide information on rock mechanics to enable greater well completion success. In addition, a comprehensive understanding of anoxia proxies can be used to identify sweet spots in the play. All of this information can be potentially provided through the use of inorganic geochemical techniques.

This paper will discuss a range of techniques from rapid and non-destructive analysis by hand held X-Ray fluorescence to highly precise and accurate data produced by inductively coupled plasma mass spectrometers. In addition we will show how inorganic geochemical analysis can be integrated with other techniques such as XRD and TOC analysis. Importantly we do not rely on samples to be provided from drill core, but also we can analyse side wall core or drill chippings.

This paper will utilise case studies from to UK onshore Bowland shale sections and the key US shales to demonstrate the wide variety of ways that the inorganic geochemical data produced can be utilised to aid in the understanding of shale gas plays. More specifically, how the bulk inorganic geochemistry can be employed to model the mineralogy of these successions. In turn the mineralogy can be used to better understand the rock mechanics and estimated TOC contents of the intervals over which analyses have been conducted. The predicted brittleness of the intervals penetrated allow for intervals that have been identified as optimal for hydraulic fracturing coupled with a high estimated TOC content to be targeted with increased confidence.

AAPG Datapages/Search and Discovery Article #90192 © 2014 European Regional Conference and Exhibition, Barcelona, Spain, May 13-15, 2014