Jin-Zhou Zhao

The Influence of Clay Minerals Types on the Oxidation Thermokinetics of Crude Oil

Abstract The effect of different clays, including kaolinite, smectite, illite, and chlorite, on the oxidation kinetics of Keke Ya crude oil (Tarim basin, China) was reported. Three distinct reaction regions were identified in all tests, known as low-temperature oxidation (LTO), fuel deposition, and high-temperature oxidation (HTO), respectively. Arrhenius method was used to analyze the TG/DTG data for obtaining activation energy. Results show that LTO and HTO activation energy of Keke Ya crude oil are 26.68 and 153.05 KJ.mol−1, while varied from 16.62 to 40.60, and from 22.18 to 96.15 KJ.mol−1 for LTO and HTO regions, respectively, by the addition of clays and reservoir cutting. Clays and reservoir cutting play an important role for decreasing the activation energy of crude oil oxidation due to the catalytic and surface area effect. It revealed that smectite is ranked first, illite is ranked second followed by chlorite and kaolinite in the aspect of catalytic ability for crude oil oxidation. This study can provide a valuable laboratory theoretical foundation for the guideline to achieve high-performance thermal enhanced oil recovery projects for different lithology reservoirs.%

Numerical Analysis on the Influence of Thermal Effects on Oil Flow Characteristic in High-Pressure Air Injection (HPAI) Process

In previous laboratory study, we have shown the thermal behavior of Keke Ya light crude oil (Tarim oilfield, branch of CNPC) for high-pressure air injection (HPAI) application potential study. To clarify the influences of thermal effects on oil production, in this paper, we derived a mathematical model for calculating oil flow rate, which is based on the heat conduction property in porous media from the combustion tube experiment. Based on remarkably limited knowledge consisting of very global balance arguments and disregarding all the details of the mechanisms in the reaction zone, the local governing equations are formulated in a dimensionless form. We use finite difference method to solve this model and address the study by way of qualitative analysis. The time-space dimensionless oil flow rate (qD) profiles are established for comprehensive studies on the oil flow rate characteristic affected by thermal effects. It also discusses how these findings will impact HPAI project performances, and several guidelines are suggested.

CH4 nanobubbles on the hydrophobic solid-water interface serving as the nucleation sites of methane hydrate

The surface hydrophobicity of solid particles plays a critical role in the nucleation of gas hydrate formation, and it was found that the hydrophobic surface will promote this nucleation process, but the underlying mechanism is still unveiled. Herein, we proposed for the first time our new theory that the formation of methane nanoscale gas bubbles on the hydrophobic surface provides the nuclei sites for further formation of methane hydrate. First, we studied the effect of hydrophobicity of particles on the nucleation of hydrate. It was found that the hydrophobic graphite and silica particles would promote the nucleation of hydrate, but the hydrophilic silica particles did not promote the methane hydrate nucleation. Then, we designed the atomic force microscopy experiment to explain this mechanism from a nanometer scale. The results showed that the methane nanobubbles were formed on the hydrophobic highly ordered pyrolytic graphite surface, but they were hard to form on the hydrophilic mica surface. These results indicated that the methane nanobubbles on the hydrophobic surface could provide the gas hydrate nucleation sites and may induce a rapid nucleation of methane hydrate.

Variation of reservoir fluid property during the high pressure air injection process

ABSTRACT This research aimed at determining the variation of reservoir fluid property during the high-pressure air injection process. For this purpose, the forward multiple contact experiment was employed by pressure–volume–temperature (PVT) system to investigate the physical property variation of the crude oil and the complex oxidation reactions. The results show: under the relative low temperature and pressure condition, instead of carbon dioxide, carbon monoxide dominates the products in the air phase. The gas/oil ratio and volume ratio increased due to the generated gas while the viscosity and density achieved a descending trend. The colloid and bitumen in the oil phase reduced by half but the amount of wax achieved a small increase. The low-temperature oxidation and pyrolysis reactions caused the fluctuated change of the different compounds. The amount of light compounds decreased at the beginning and then increased while that of heavy compounds showed the opposite trend. But at last, due to the H/C ratio, the light compounds increased to more than their initial value.