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Download fileCharacterization of the Pore Structure and Fluid Movability of Coal-Measure Sedimentary Rocks by Nuclear Magnetic Resonance (NMR)
journal contribution
posted on 2021-08-26, 18:05 authored by Na Zhang, Shuaidong Wang, Fangfang Zhao, Xiaoming Sun, Manchao HeAnalyzing and mastering
the pore structure and fluid movability
characteristics of coal-measure sedimentary rocks is significant for
the safe and effective development of unconventional resources. In
this work, nuclear magnetic resonance (NMR) experiments were carried
out on three common fine sedimentary rocks (i.e., shale, mudstone,
and sandstone) from a coal-measure stratum in northern China. NMR
transverse (T2) of the water-saturated
and centrifuged rock samples are compared and analyzed. Moreover,
the pore size distribution (PSD) and the free-fluid volume index (FFI)
of the investigated samples are discussed. Results have shown that
the shale and mudstone samples are mainly dominated by adsorption
pores with a diameter of 0.01–1 μm, while the sandstone
samples are dominated by seepage pores with a diameter of 1–100
μm. The FFI results calculated by the cutoff and the area methods
are 11.15–77.62 and 7.56–75.96%, respectively. There
are good correlations between FFI and porosity, permeability, and
reservoir quality index (RQI). Also, the effects on FFI are different
on various kinds of clay minerals. The contents of illite and chlorite
are negatively correlated with FFI, while kaolinite is positively
correlated with FFI.
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Keywords
seepage poresPore Structurefluid movability characteristicsadsorption poresRQICoal-Measure Sedimentary Rocksclay mineralsT 2rock samplesPSDreservoir quality indexfree-fluid volume indexsandstone samplespore structureFluid Movabilitypore size distributionNMRarea methodscoal-measure stratumFFI resultsmudstone samples