Abstract

The present study investigates the use of energetic stimulation for the purpose of creating fracture networks for inter-well communication. Explosive loading is applied in scaled wellbores within a polymethylmethacrylate (PMMA) sample. Prior to testing, the experiments are computationally studied to predict the explosive behavior as well as the generation of a shock induced fracture network. In order to capture the energetic event, the PMMA samples are observed using high speed shadowgraph and photon doppler velocimetry techniques to assess effects of the energetically driven dynamic stresses. The quantification of wave interaction and subsequent fracture growth in the transparent PMMA material is used as validation against computational models. Insights gained may guide practical application of subsurface energetics usage to maximize interconnectivity of artificial fracture networks. This work seeks to lower the fracturing resources required to create wellbore connectivity between wellbores in low permeability reservoirs typical of enhanced geothermal systems (EGS).

Introduction

Hydraulic fracturing is the most widely used method increase wellbore connectivity within a formation. This has gained significant notoriety in the shale oil boom in the United States where formation rock has permeability artificially increased through the manmade fracture network. Geothermal formations share similar traits, in that operators have highly consolidated, poor permeability rock which from which they are trying to create connectivity. Enhanced Geothermal Systems (EGS) consist of two of more wellbores, situated some distance away from each other, an injection well uses a volume of fractured formation to communicate to a producing wellbore. In this case the formation adds heat to the injection fluid, allowing for extraction of the geothermal energy from the produced fluid. Other geothermal assets may have natural reservoir drive and production of steam such as the Geysers field in California, USA. Both types of geothermal completions can benefit from increased connectivity from formation to wellbore created by modern stimulation methods.

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