Title: Irreducible water distribution from nuclear magnetic resonance and constant-rate mercury injection methods in tight oil reservoirs

Authors: Meng Chen; Min Li; Jinzhou Zhao; Yan Kuang

Addresses: State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu 610500, China ' State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu 610500, China ' State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu 610500, China ' School of Geoscience and Technology, Southwest Petroleum University, Chengdu 610500, China

Abstract: Fifteen tight cores from Chinese Ordos basin were selected to obtain the irreducible water from fully-saturated by centrifuging with rotational speeds increased from 0 to 10,000 r/min, T2 spectra were measured by a low-field NMR core analysis unit concurrently. The fully-saturated T2 spectra showed a tri-modal pattern and ranged in 0~6, 6~100 and 100~1000 ms, which corresponded to micro-, meso- and macro- pore spaces, respectively. The irreducible water reached at the speed of 10,000 r/min with water saturation varied in 38.695~55.728%. Pore distributions by constant-rate mercury injection were adopted to get the transform coefficients between T2 time and pore-throat radius. SEM and thin sections were also introduced to support an intuitive understanding. It was found that irreducible water mainly remained in pores and throats ranged in 0.01~2 and 10~100 μm. The micro- pore spaces dominated by clay minerals, irregular microstructure and rough particles surface were considered to be dominantly effect factors. [Received: May 10, 2016; Accepted: February 2, 2017]

Keywords: tight oil; irreducible water; nuclear magnetic resonance; constant-rate mercury injection; pore-throat structure.

DOI: 10.1504/IJOGCT.2018.090972

International Journal of Oil, Gas and Coal Technology, 2018 Vol.17 No.4, pp.443 - 457

Received: 05 Oct 2016
Accepted: 02 Feb 2017
Published online: 05 Apr 2018 *

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