Oil Occurrence States in Shale Mixed Inorganic Matter Nanopores

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.

Molecular dynamics simulation on the displacement behaviour of crude oil by CO2/CH4 mixtures on a silica surface

“…We suppose that the first three peaks correspond to clearly discernible adsorption layer, while the last peak represents free shale oil, as evidenced by its density close to that of decane in its natural state, that is approximately 0.72 g cm −3 . 39,40 Upon gas injection, in the case of pure CO 2 , the peak of the oil layer density curve shifts to the free state region, indicating that the majority of adsorbed oil has converted to the free oil. 41 In the presence of CH 4 in the gas phase, the highest density peak of the oil layer remains in the adsorbed state region.…”

Hydrocarbon Transportation in Heterogeneous Shale Pores by Molecular Dynamic Simulation

“…Among the clay minerals, illite, MMT, and interstratified illite/MMT are the predominant constituents, with a small proportion of interstratified chlorite/MMT. According to the previous study of the research group [69], the whole rock analysis and clay mineral analysis were performed on rock samples of Member Qing 1 in the Songliao Basin using XRD. The results indicated that the primary components of inorganic matter were quartz and clay minerals.…”

A Comprehensive Review of the Oil Flow Mechanism and Numerical Simulations in Shale Oil Reservoirs

“…Organic matter in shale can be divided into free state, adsorbed state, and dissolved state [50,51]. Generally speaking, free oil is mainly composed of light hydrocarbon components with good fluidity, mainly in the pore joints, microfractures, layer interstices, and matrix pores with a relatively large pore throat diameter [52].…”