On the connectivity anisotropy in fluvial Hot Sedimentary Aquifers and its influence on geothermal doublet performance

Cees J.L Willems,Hamidreza M Nick,Marinus E Donselaar,Gert Jan Weltje,David F Bruhn

doi:10.1016/j.geothermics.2016.10.002

Abstract

This study finds that the geothermal doublet layout with respect to the paleo flow direction in fluvial sedimentary reservoirs could significantly affect pump energy losses. These losses can be reduced by up to 10% if a doublet well pair is oriented parallel to the paleo flow trend compared to perpendicular. The chance that flow paths are formed perpendicular to this trend strongly depends on the net sandstone volume in the reservoir. Detailed fluvial facies architecture realisations which are used in this study, are generated with a process-based approach utilizing geological data from the Lower Cretaceous Nieuwerkerk Formation in the West Netherlands Basin. Finally, this study emphasizes the importance of detailed facies architecture modelling for the assessment of both risks and production strategies in Hot Sedimentary Aquifers.

Highlights

Hot Sedimentary Aquifers (HSA) are commonly exploited by a doublet system, consisting of a hot-water production and a coldwater reinjection well
Previous work on connectivity in sedimentary reservoirs identified several main factors that control the chance that sandstone bodies connect: (1) the netsandstone volume or net-to-gross (N/G); (2) the sandstone body geometry, and (3) the range in paleo- flow direction, which determines the reservoir trend (King, 1990; Larue and Hovadik, 2006, 2008; Geel and Donselaar, 2007; Ainsworth, 2005; Pranter and Sommer, 2011)
A pressure difference was applied to opposite model boundaries parallel, perpendicular and vertical to the paleo flow direction

Summary

Introduction

Hot Sedimentary Aquifers (HSA) are commonly exploited by a doublet system, consisting of a hot-water production and a coldwater reinjection well. Detailed knowledge of the size, shape, spatial distribution and connectivity of the fluvial sandstone bodies (or: fluvial reservoir architecture) is required to assess the risk of pressure communication loss between the wells and the inherent economic risk of the geothermal energy production projects (Fig. 1). Previous work on connectivity in sedimentary reservoirs identified several main factors that control the chance that sandstone bodies connect: (1) the netsandstone volume or net-to-gross (N/G); (2) the sandstone body geometry, and (3) the range in paleo- flow direction, which determines the reservoir trend (King, 1990; Larue and Hovadik, 2006, 2008; Geel and Donselaar, 2007; Ainsworth, 2005; Pranter and Sommer, 2011). Studies into the risk assessment of connectivity are dominantly focused on the optimization of hydrocarbon

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