The impact of reduction of doublet well spacing on the Net Present Value and the life time of fluvial Hot Sedimentary Aquifer doublets

C.J.L Willems,H.M Nick,T Goense,D.F Bruhn

doi:10.1016/j.geothermics.2017.02.008

Abstract

This paper evaluates the impact of reduction of doublet well spacing, below the current West Netherlands Basin standard of 1000–1500m, on the Net Present Value (NPV) and the life time of fluvial Hot Sedimentary Aquifer (HSA) doublets. First, a sensitivity analysis is used to show the possible advantage of such reduction on the NPV. The parameter value ranges are derived from West Netherlands Basin HSA doublet examples. The results indicate that a reduction of well spacing from 1400 to 1000m could already improve NPV by up to 15%. This effect would be larger in more marginally economic HSA doublets compared to the West Netherlands Basin base case scenario. The possibility to reduce well spacing is supported by finite element production simulations, utilizing detailed facies architecture models. Furthermore, our results underline the necessity of detailed facies architecture models to assess the potential and risks of HSA doublets. This factor significantly affects doublet life time and net energy production of the doublet.

Highlights

Large potential resources of heat are stored in sedimentary rocks
This paper presents a modelling based study on the advantages and impacts of a well spacing reduction in Hot Sedimentary Aquifers (HSA) doublets
Our results indicate that a reduction of 400 m well spacing could lead to a Net Present Value (NPV) improvement of up to 15%

Summary

Introduction

Large potential resources of heat are stored in sedimentary rocks. In the Netherlands alone, the Dutch geological survey estimated the total recoverable heat from this type of resource to be approximately 55 times larger than the annual heat consumption (Kramers et al, 2012; CBS). Hot Sedimentary Aquifers (HSA) are especially suitable for ‘direct use’ or heat production, because they are often found in areas with average thermal gradient (Boxem et al, 2011; Pluymaekers et al, 2012). In these areas temperatures for commercial electricity production (e.g., Shengjun et al, 2011) are found at depths where pore space is generally diminished. A large gap currently exists between HSA potential and exploitation This gap is a result of a combination of high initial investment costs and large uncertainties in both doublet life time and capacity. The height of the initial investment is mainly influenced by a combination of high drilling costs and

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