Pyrolysis and Oxidation of Asphaltene-Born Coke-like Residue Formed onto in Situ Prepared NiO Nanoparticles toward Advanced in Situ Combustion Enhanced Oil Recovery Processes

Abstract

Pyrolysis and oxidation of asphaltene-born coke-like residue formed onto ex situ and in situ prepared NiO nanoparticles as initial steps toward developing advanced in situ combustion enhanced oil recovery (EOR) processes were studied. The in situ synthesized NiO nanoparticles in heavy oil matrix, containing coke-like residue, were characterized by X-ray diffraction, Brunauer−Emmett−Teller, field-emission scanning electron microscopy, and energy-dispersive X-ray mapping techniques. The pyrolysis and postpyrolysis oxidation of the coke residue were investigated by temperature-programmed pyrolysis (TPP) and temperature-programmed oxidation (TPO) methods, respectively. Oxidation kinetics of the coke residue was described by the Kissinger−Akahira−Sunose isoconversional method. The results showed a higher percentage of coke residue on the in situ prepared nanoparticles than the ex situ employed ones. Eventually, during the TPP of the coke residue, the amount of carbon oxides released per total amount of the coke is 18.6% higher for the in situ NiO as compared to the ex situ NiO nanoparticles. This may be attributed to the uniform dispersion of the in situ NiO in the coke residue. Furthermore, compared to the ex situ NiO, the in situ NiO nanoparticles shift the oxidation temperature of the coke residue by about 100 °C to lower temperature. Multistep kinetics was predicted with a significant drop of the activation energy of the oxidation of the coke residue in the presence of in situ and ex situ NiO nanoparticles, confirming their catalytic effect. However, the preexponential factor, as a representation of the collision efficiency, is significantly higher over the in situ NiO compared to the ex situ NiO, leading to the enhanced oxidation of the coke residue. This may be attributed to the loss of surface area due to particle aggregation for the case of ex situ preparation, as well as the orientation of asphaltene molecules during the adsorption onto the surface. The asphaltenes could be aligned mostly vertically over the in situ NiO surface; thus the vertical alignment provides good channels for diffusion of gas-phase oxygen onto the surface leading to high collision efficiency and catalytic activity.

Nanotechnology Applied to Thermal Enhanced Oil Recovery Processes: A Review

“…The results have shown that nanocatalysts can considerably reduce the decomposition temperature of the asphaltenes as well as the effective activation energy, confirming their catalytic activity toward decomposition of long-chain hydrocarbons towards lighter fractions with smaller molecular weight, which implies viscosity reduction and mobility improvement of the producing heavy crude oils [31,32]. The partial upgrading of heavy crude oil is related to many types of catalytic processes such as thermal cracking [33,34], aquathermolysis [24,35], hydrocracking [36], oxidation [37][38][39][40][41][42], pyrolysis [38,[42][43][44], and steam gasification [30,[45][46][47][48][49].…”

“…After the asphaltene molecules are subjected to thermal processes involving oxidation, pyrolysis, gasification reactions, and coke formation can be generated. In both pyrolysis and gasification, coke yield of 61.2% [33] and 63.3% [38] can be generated, respectively, while oxidation completely inhibits the formation of this residue. To understand this phenomenon in greater detail, Figure 5 shows a basic scheme of the reaction associated with the oxidation temperature of asphaltenes and describes the decomposition of these molecules into lighter fractions by means of two main ways: oxygen and free radicals [89].…”

“…Information about the efficiency of the process through the use of nanotechnology is obtained through different tests. Thus, the type of tests can be classified into two main groups, static tests and dynamic tests [29,30,32,33,38,41,45,82,152,153]. In the reservoir characterization and engineering stages, it is of primary importance to analyze the characteristics and dynamics of production of the field in order to determine the viability of the steam injection technology through the use of nanofluids.…”

“…Relationship between activation energy (Eα) with (a) conversion degree (α) and (b) temperature for thermo-oxidative decomposition of post-temperature-programmed pyrolysis (TPP) samples in the presence and absence of NiO nanoparticles in-situ and ex-situ. Reprinted with permission[38]; Copyright 2018, ACS Publications.…”

A Critical Review of Reservoir Simulation Applications in Key Thermal Recovery Processes: Lessons, Opportunities, and Challenges

“…It was found that the coke deposition in pores turned large pores into micropores which deteriorated permeability. A series of experiments were conducted to understand coke formation under different reaction conditions , and the presence of montmorillonites and nanoparticles . Yu et al in 2017 concluded that clay could accelerate reaction rates and improve an ignition process .…”