TY - JOUR

T1 - Pore connectivity characterization of shale using integrated wood's metal impregnation, microscopy, tomography, tracer mapping and porosimetry

AU - Zhao, Jianhua

AU - Hu, Qinhong

AU - Liu, Keyu

AU - Jin, Zhijun

AU - Dultz, Stefan

AU - Kaufmann, Josef

AU - Fan, Yuchen

N1 - Funding Information: This research was supported by the National Natural Science Foundation of China (Nos. 41802141 and 41830431 ), Natural Science Foundation of Shandong Province (No. ZR2019QD009 ), the Foundation of State Key Laboratory of Shale Oil and Gas Enrichment Mechanisms and Effective Development (No. 3355007-18-ZC0613-0105 ) at Wuxi Institute of Petroleum Geology, Sinopec Petroleum Exploration & Production Research Institute, and the Fundamental Research Funds for the Central Universities (No. 18CX02006A ). We would like to thank Texas Bureau of Economic Geology and Jianghan Oilfield Company of SINOPEC for providing shale core samples.

PY - 2020/1/1

Y1 - 2020/1/1

N2 - The pore connectivity of tight shale reservoirs plays an essential role in the movement of shale gas and oil, however, the characteristics of connected pores in shale with a multi-scale and coupled pore-fracture system are poorly constrained. Working with typical American (Barnett and Eagle Ford) and Chinese (Longmaxi) shale samples in 2D/3D spaces at nano- to mm-scales, connective pores were intruded with a molten alloy (Wood's metal; WM) under a temperature of ~85 °C and high pressure (60, 300, and 600 MPa) conditions. After solidification of the alloy at room temperature, polished sections were used to map WM components by field emission-scanning electron microscopy (SEM), micro- and nano-X-ray tomography and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). These tests were supplemented with mercury intrusion porosimetry (MIP) for pore-fracture throat size distribution. The shale matrix is generally characterized by low pore connectivity; however, the extent of connectivity within μm-sized and dispersed organic matter (OM) particles is high, with the observed WM-filled pore space ranging from 10% to 70% (averaged at 43%) for the Barnett Shale sample. The grain-edge fractures are important channels to connect multiple OM-hosted pore systems dispersed in shale matrix. Our work illustrates that shales exhibit a dual-connectivity behavior, with the effective porosity decreasing sharply as the distance from the sample boundary increases; the good pore connectivity zone away from the edge of sample is 500 μm under a pressure of 600 MPa for the Barnett Shale sample.

AB - The pore connectivity of tight shale reservoirs plays an essential role in the movement of shale gas and oil, however, the characteristics of connected pores in shale with a multi-scale and coupled pore-fracture system are poorly constrained. Working with typical American (Barnett and Eagle Ford) and Chinese (Longmaxi) shale samples in 2D/3D spaces at nano- to mm-scales, connective pores were intruded with a molten alloy (Wood's metal; WM) under a temperature of ~85 °C and high pressure (60, 300, and 600 MPa) conditions. After solidification of the alloy at room temperature, polished sections were used to map WM components by field emission-scanning electron microscopy (SEM), micro- and nano-X-ray tomography and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). These tests were supplemented with mercury intrusion porosimetry (MIP) for pore-fracture throat size distribution. The shale matrix is generally characterized by low pore connectivity; however, the extent of connectivity within μm-sized and dispersed organic matter (OM) particles is high, with the observed WM-filled pore space ranging from 10% to 70% (averaged at 43%) for the Barnett Shale sample. The grain-edge fractures are important channels to connect multiple OM-hosted pore systems dispersed in shale matrix. Our work illustrates that shales exhibit a dual-connectivity behavior, with the effective porosity decreasing sharply as the distance from the sample boundary increases; the good pore connectivity zone away from the edge of sample is 500 μm under a pressure of 600 MPa for the Barnett Shale sample.

KW - LA-ICP-MS tracer mapping

KW - Mercury intrusion porosimetry

KW - Pore connectivity

KW - SEM microscopy

KW - Wood's metal impregnation

KW - X-ray tomography

UR - http://www.scopus.com/inward/record.url?scp=85072840434&partnerID=8YFLogxK

U2 - 10.1016/j.fuel.2019.116248

DO - 10.1016/j.fuel.2019.116248

M3 - Article

AN - SCOPUS:85072840434

VL - 259

JO - Fuel

JF - Fuel

SN - 0016-2361

M1 - 116248

ER -