Contributions of pore-throat size distribution to reservoir quality and fluid distribution from NMR and MIP in tight san
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ORIGINAL PAPER
Contributions of pore-throat size distribution to reservoir quality and fluid distribution from NMR and MIP in tight sandy conglomerate reservoirs Meng Chen 1
&
Jiacai Dai 1 & Xiangjun Liu 1 & Yan Kuang 1 & Minjun Qin 2 & Zhongtao Wang 2
Received: 14 June 2018 / Accepted: 7 December 2018 / Published online: 28 December 2018 # Saudi Society for Geosciences 2018
Abstract Overall pore-throat size distribution is a critical foundation for evaluating tight sandy conglomerate reservoirs. However, the pore-throat size cannot be easily obtained from a single technic due to the complex microstructure. In this paper, a new method was introduced to characterize the microstructure by combining thin sections, scanning electron microscopy (SEM), pressurecontrolled injected mercury (PMI), rate-controlled injected mercury (RMI), and nuclear magnetic resonance (NMR). Twentyfour tight sandy conglomerate cores from the Baikouquan Formation of the Mabei oil field, northwest China, were selected to conduct the series of experiments. Overall pore-throat size distribution (TRD) was reconstructed by combining mercury injection porosimetry (MIP) with NMR with pores that were equivalent to triangular cross-section; the radii of the inscribed spheres were obtained to weaken the influence of irregular shapes by RMI. Irreducible water saturation of the cores was achieved by nitrogen displacement, which decreases with increasing of micropore proportion. An ideal relationship between permeability, movable water saturation, and micropore percentages was constructed which indicates the effect of microstructure on reservoir quality and fluid distribution in tight sandy conglomerate reservoirs. Keywords Tight sandy conglomerate reservoirs . Mercury injection porosimetry . Nuclear magnetic resonance . Overall pore-throat size . Permeability . Fluid distribution
Introduction With the expanding demands of energy throughout the world and progressively exhausted conventional oil reservoirs, the assessment of alternative supplementary energy sources such as tight oil has become increasingly important (Ghanizadeh et al. 2015; Chen et al. 2018a). Due to the complex microstructure and a significant portion of nanopores and throats of tight oil reservoirs, the natural productivity of a single well is usually lower than expected (Leng et al. 2015; Zhao et al. 2015). So, understanding the microstructure and its effect on petro-physical properties and the fluid distribution is essential
* Meng Chen [email protected] 1
School of Geoscience and Technology, Southwest Petroleum University, Chengdu 610500, China
2
Production Logging Center, China Petroleum Logging Co. Ltd., Xi’an 710200, China
for evaluation and efficient exploitation in tight sandy conglomerate reservoirs (Clarkson et al. 2011). Existing common techniques for microstructure analysis include scanning electron microscopy (SEM), thin-section analysis, X-ray computed tomography (CT), mercury injection porosimetry (MIP, including pressure-controlled mercury injection (PMI) and
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