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Effect of divalent ions on solid-fluid interface, as observed by NMR transverse relaxation timeLeonardo MeirelesMSc Petroleum EngineeringDTU - Danmarks Tekniske Universitet

SPE student paper contestImperial College of London2nd June 2014

Danmarks Tekniske UniversitetContents 28/05/2014Pre-thesis project - Leonardo Meireles2MotivationTheoryExperimentsResultsConclusionsDanmarks Tekniske Universitet2Motivation: Can divalent ions in seawater change chalk wettability? Generally water flooding of carbonate reservoirs seen as a challenge.Ekofisk: Approaching 50% recovery (year) against a 17% prediction. oil recovery increased when using seawater compared to formation brine as displacing uid.28/05/2014Pre-thesis project - Leonardo Meireles3Danmarks Tekniske UniversitetNormally, water ooding of naturally fractured carbonate reservoirs is a great challenge due to low water wetness in the matrix blocks. 3Theory:How does NMR measure solid-fluid interaction?28/05/2014Pre-thesis project - Leonardo Meireles4

Danmarks Tekniske UniversitetThe fastest the T2surface relaxation, the higher the interaction!Accounts for the effectiveness of the surface in promoting spin-relaxationConsidered to be a measure of the strength of interactions between uids and pore walls

4Experiments:Breaking down seawater28/05/2014Pre-thesis project - Leonardo Meireles5 Ca2+, Na2+, Mg2+, and SO42- are the predominant ions in seawater.An outcrop chalk (Stevns Chalk) was used in SSA of 2, 5 and 10m2.

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Danmarks Tekniske Universitet5Results:Comparison of T2surf in distinct brines/concentrations28/05/2014Pre-thesis project - Leonardo Meireles6Danmarks Tekniske Universitet6Results:Comparison of T2surf in distinct brines/concentrations28/05/2014Pre-thesis project - Leonardo Meireles7Danmarks Tekniske Universitet7Results:Comparison of T2surf in distinct brines/concentrations28/05/2014Pre-thesis project - Leonardo Meireles8Danmarks Tekniske Universitet8Results:Comparison of T2surf in distinct brines/concentrations28/05/2014Pre-thesis project - Leonardo Meireles9Danmarks Tekniske Universitet9Results:Comparison of T2surf in distinct brines/concentrations28/05/2014Pre-thesis project - Leonardo Meireles10Danmarks Tekniske Universitet10Results:Comparison of T2surf in distinct brines/concentrations28/05/2014Pre-thesis project - Leonardo Meireles11Danmarks Tekniske Universitet11Results:Bound fluid calculations28/05/2014Pre-thesis project - Leonardo Meireles12Danmarks Tekniske Universitet12Results:Bound fluid calculations28/05/2014Pre-thesis project - Leonardo Meireles13Danmarks Tekniske Universitet13Results:Bound fluid calculations28/05/2014Pre-thesis project - Leonardo Meireles14Danmarks Tekniske Universitet14Results:Porosity measurements corroborates bound fluid calculations28/05/2014Pre-thesis project - Leonardo Meireles15Danmarks Tekniske Universitet15Conclusions:

28/05/2014Pre-thesis project - Leonardo Meireles16All brines influenced to some degree the relaxation times in bound water.Magnesium chloride brine effectively increased relaxivity, even at very low concentrations.Faster relaxation times translated in a lower amount of adsorbed fluid.Porosity measurements seem to validate bound fluid calculated through NMR.Danmarks Tekniske Universitet16