Wettability of Chalk and Argillaceous Sandstones Assessed from T1/T2 Ratio

Konstantina Katika, M. Saidian, Ida Lykke Fabricius

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Abstract

Low-field NMR relaxation of the fluids inside the porous rock is the result of bulk and surface relaxation of the protons inside the pore fluid. Bulk relaxation is a fluid property when the solid-fluid interaction is minimized. Surface relaxation is the result of the solid-fluid interaction related to mineral properties. Thus, longitudinal, T1, and transverse, T2, relaxation times should in principle be similar. However, microscopic magnetic gradients related to minerals can shorten T2 as compared to T1 provided the saturating fluid has high affinity to the solid. We consequently find that the T1/T2 ratio can quantify the affinity between the rock and wetting pore fluid. The affinity is a measure directly linked to wettability.
In order to investigate the T2-shortening, we performed T1-T2 NMR experiments on different samples of chalk, Berea sandstone, and chloritic greensand, saturated either with water, oil or oil/water at irreducible water saturation. The T1/T2 ratio obtained from T1-T2 maps reflects the T2-shortening. We compare the T1/T2 ratio for the same type of rock, saturated with different fluids. The chalk shows high affinity for water, Berea sandstone has no clear preference for oil and water whereas chloritic greensand shows different behavior for small and large pores
Original languageEnglish
Publication date2016
Number of pages5
Publication statusPublished - 2016
Event78th EAGE Conference & Exhibition 2016 - Reed Messe Wien, Vienna, Austria
Duration: 30 May 20162 Jun 2016
Conference number: 78

Conference

Conference78th EAGE Conference & Exhibition 2016
Number78
LocationReed Messe Wien
CountryAustria
CityVienna
Period30/05/201602/06/2016

Cite this

Katika, K., Saidian, M., & Fabricius, I. L. (2016). Wettability of Chalk and Argillaceous Sandstones Assessed from T1/T2 Ratio. Paper presented at 78th EAGE Conference & Exhibition 2016, Vienna, Austria.