Oil Occurrence States in Shale Mixed Inorganic Matter Nanopores

Shuang Liang,Bo Liu,Fei-Yu Tao,Shuo Sun,An-Qi Shen,Jia-Ming Wang,Yi-Kun Liu

doi:10.3389/feart.2021.833302

Shuang Liang, Bo Liu + Show 5 more

Open Access

https://doi.org/10.3389/feart.2021.833302

Copy DOI

Abstract

In present paper, the mineral and fluid compositions of shale oil from the Songliao Basin are analyzed systematically using core samples, X-ray diffractometer (XRD), and gas chromatography (GC). The effects of shale mineral composition, pore size, temperature, and pressure on the mass density of the adsorbed layers are then studied utilizing molecular dynamics simulation. The results show that illite and quartz are predominant in the micro petrological components of the shale, and nC19 is the main carbon peak. The fluid consists primarily of n-alkane molecules, and nC19 is found to be representative of the shale oil composition. Moreover, the adsorbing effect of quartz-illite mixed wall is between that of a pure mineral wall (illite and quartz), indicating that the selection of a mixed wall is similar to the actual shale composition. If the pores are inorganic, the minimum pore size of only adsorption oil is smaller than the organic pores. The critical adsorption point of shale oil in inorganic pores is less than 3.2 nm. Furthermore, compared to pressure, the temperature has a more significant effect on fluid adsorption due to the correlation with the kinetic energy of alkane molecules. This research shows the oil occurrence status in inorganic matter nanopore with a mixed solid wall, and provides theoretical support for shale oil exploration.

Highlights

A continuous decline in conventional oil reserves has led to increasing attention to unconventional oil resources (Awan et al, 2021), especially shale oil, due to its vast number of resources and considerable production rate after fracturing (Zhou et al, 2020a; Zhou et al, 2020b)
The adsorption effect of the quartz-illite mixed wall is between that of the pure mineral walls, indicating that the selection of a mixed wall is closer to actual shale samples
Effect of Pore Size on n-Alkanes Adsorption In Figure 6A, we presented the continuous mass density profiles of nC19 in mixed nanopores at pore sizes of 2, 3.2, 5, and 7.2 nm

Summary

INTRODUCTION

A continuous decline in conventional oil reserves has led to increasing attention to unconventional oil resources (Awan et al, 2021), especially shale oil, due to its vast number of resources and considerable production rate after fracturing (Zhou et al, 2020a; Zhou et al, 2020b). Occurrence in Mixed Inorganic Nanopores uneven fluid distribution, and transport, the resource estimation, total volume flux, and economic evaluation are affected They are affected by other various factors, such as temperature, pressure, and pore size. Previous numerical simulation studies provided essential insights into the occurrence state and liquid flow mechanisms in shale nanopores, most focused on the single composition pore wall. No documented study has been found that investigated the effect of temperature, pressure, and pore size on the occurrence states of liquid alkane under the condition of a mixed shale wall. In present study, we focus on the experiment result of XRD and GC on the Songliao Basin shale, using equilibrium molecular dynamics simulation to investigate the adsorption characteristics of oil in the inorganic matter mixed solid wall and single mineral solid wall of shale. The simulation snapshots were created by OVITO 3.0.0 (Stukowski, 2010)

RESULTS AND DISCUSSION

CONCLUSION

DATA AVAILABILITY STATEMENT