Significant filter cake formation in fine sand K 10 6 ms Not limited by other experimental parameters Filter cake formation is strongly dependent on the grain size Different filter cake characteristics within an heterogeneous aquifer ID: 1027197
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1. First preliminary study focussing on the effect of the filter cake formation in unconsolidated sedimentsSignificant filter cake formation in fine sand (K = 10-6 m/s)Not limited by other experimental parametersFilter cake formation is strongly dependent on the grain sizeDifferent filter cake characteristics within an heterogeneous aquifer Rein Nijhoflinkedin.com/in/reinnijhof/reinnijhof@hotmail.comThe effect of filter cake deposition on the hydraulic conductivity of boreholesRein Nijhof, Jan van Lopik and Martin Bloemendal1234Backfilling of BHEsMethod: Falling head testsFig. 1 – Schematic illustration of a ground source heat pump with a borehole heat exchanger.Fig. 2 – Backfilled BHE vs. laboratory configuration.Challenge:Effective sealing of the boreholeResearch Question:What is the effect of filter cake formation on sealing capacity in unconsolidated sediments?ResultsConclusionHydraulic conductivity loss in fine sand → filter cakeAquiferBackfill materialFig. 3 – Hydraulic conductivity vs. grain size. fine medium coarse
2. 1. Backfilling of BHEsRein Nijhof - Email - LinkedInBHEs are essential for the energy transitionLow construction costs High production rates → small diameter drilling, less backilling materialChallenge: proper backfilling of BHEs …There is an urgent need to improve techniques to effectively and efficiently backfill BHEs.Fig. 1 – Schematic illustration of a ground source heat pump with a borehole heat exchanger.
3. 1. Backfilling of BHEsRein Nijhof - Email - LinkedInConventional methods:Grout → environmental harmfulClay → expensiveClay at confining layers → risk of inadequate plugging at confining layersResearch question:What is the effect of filter cake formation on sealing capacity in unconsolidated sediments?
4. 2. MethodRein Nijhof - Email - LinkedInSimulate the processes during the construction of the BHE in the laboratory.Hydraulic conductivity → Falling head testsFig. 2 – Backfilled material in BHE vs. laboratory configuration.
5. 2. MethodRein Nijhof - Email - LinkedInFour variables: 1. Different bentonite concentrations of the drilling fluid18 kg/m330 kg/m342 kg/m32. Different sands d50 (mm)Dunesand 0.22 0.4-0.8 mm filter sand 0.650.7-1.25 mm filter sand 0.953. Exposure to the drilling fluid (min)15304. Backfilling in presence or absence of the drilling fluid→ a total of 36 scenario’sFig. 3 – Laboratory configuration, schematic in practice.
6. 3. ResultsRein Nijhof - Email - LinkedIn
7. 3. Results
8. 4. ConclusionRein Nijhof - Email - LinkedInFirst preliminary study focussing on the effect of the filter cake formation in unconsolidated sedimentsSignificant filter cake formation in dunesand (K = 10-6)Not limited by other experimental parametersFilter cake formation is highly dependent on the grain sizeDifferent filter cake characteristics within an heterogeneous aquifer Further research Improved protocolCareful designed drilling fluid