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A New Method for Petrophysical Parameter Estimation in Tight Sandstone Based on NMR Echo DataNormal access

Authors: G. Jin, R. Xie, J. Guo, L. Gao, M. Gu and B. Wu
Event name: 81st EAGE Conference and Exhibition 2019
Session: Poster: Core Analysis & Rock Physics
Publication date: 03 June 2019
DOI: 10.3997/2214-4609.201901432
Organisations: EAGE
Language: English
Info: Extended abstract, PDF ( 479.28Kb )
Price: € 20

Bound water saturation (Swb) and permeability are two important petrophysical parameters. However, it is challengeable to estimate Swb and permeability in tight sandstone by conventional methods based on nuclear magnetic resonance (NMR) transverse relaxation time (T2) distributions. A new method is presented to estimate Swb and permeability using integral transforms of the NMR echo data in tight sandstone. First, the tapered cut-off function was established using the sinc function based on the film model; the Swb was directly estimated by the sinc transform of the NMR echo data without an inversion of the T2 distribution. Then the tapered cut-off function representing the proportion coefficients of the free fluids in the pore space was added to the arithmetic mean of the T2 (T2am) as a weight to construct the weighted T2am (T2wam). The T2wam was highly suitable for reflecting the seepage ability of the pores and was directly calculated from the NMR echo data using an integral transform without an inversion. A new permeability estimation model was developed based on the T2wam. The core experimental results verified the effectiveness of the new method.

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