Xu, F.; Jiang, H.; Liu, M.; Jiang, S.; Wang, Y.; Li, J. NMR-Based Analysis of Fluid Occurrence Space and Imbibition Oil Recovery in Gulong Shale. Processes2023, 11, 1678.
Xu, F.; Jiang, H.; Liu, M.; Jiang, S.; Wang, Y.; Li, J. NMR-Based Analysis of Fluid Occurrence Space and Imbibition Oil Recovery in Gulong Shale. Processes 2023, 11, 1678.
Xu, F.; Jiang, H.; Liu, M.; Jiang, S.; Wang, Y.; Li, J. NMR-Based Analysis of Fluid Occurrence Space and Imbibition Oil Recovery in Gulong Shale. Processes2023, 11, 1678.
Xu, F.; Jiang, H.; Liu, M.; Jiang, S.; Wang, Y.; Li, J. NMR-Based Analysis of Fluid Occurrence Space and Imbibition Oil Recovery in Gulong Shale. Processes 2023, 11, 1678.
Abstract
The Gulong shale oil reservoir is formed in freshwater to slightly saline lacustrine basins, mainly consisting of pure shale geological structure, which is quite different from other shale reservoirs around the world. Currently, the development of Gulong shale oil mainly relies on hydraulic fracturing, while the subsequent shut-in period for imbibition has been proven to be an effective method for enhancing shale oil recovery. To clarify the characteristics of fluid occurrence space and the variation of fluid occurrence during saltwater imbibition in Gulong shale, this paper carried out porosity and permeability tests on Gulong shale cores, and analyzed the fluid occurrence space characteristics and imbibition oil recovery based on nuclear magnetic resonance (NMR). In the porosity and permeability tests, the porosity measured by saturation method was calibrated using NMR T2 spectra. Combined with the identification of fractures in shale cores using micro-CT and the analysis of porosity and permeability parameters, it was found that the permeability of shale cores was related to the development of fractures in shale cores. Through the testing and analysis of NMR T1-T2 two-dimensional spectra of the shale cores before and after saturation with oil, it was found that the shale mainly contains heavy oil, light oil, and clay-bound water, and they were distributed in different positions in the T1-T2 spectrum. Finally, the T1-T2 two-dimensional spectra of the shale core at different imbibition stages were analyzed, and it was found that the saltwater mainly entered the minuscule inorganic pores of clay minerals during the imbibition process, and squeezed the larger-sized inorganic pores containing light oil through the hydration expansion effect, thus expelling the light oil from the shale core and achieving the purpose of enhanced oil recovery.
Keywords
nuclear magnetic resonance; shale oil; occurrence space characteristics; imbibition
Subject
Engineering, Energy and Fuel Technology
Copyright:
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
