Natural gas hydrate (NGH) is widely distributed worldwide with great reserves and is generally accepted as a promising alternative energy source. However, sustainable, efficient, and safe NGH devel...

Sand Production Management during Marine Natural Gas Hydrate Exploitation: Review and an Innovative Solution

Synergy of hydrophilic nanoparticle and nonionic surfactant on stabilization of carbon dioxide-in-brine foams at elevated temperatures and extreme salinities

Microscopic visualization of greenhouse-gases induced foamy emulsions in recovering unconventional petroleum fluids with viscosity additives

A novel strategy to reduce carbon emissions of heavy oil thermal recovery: condensation heat transfer performance of flue gas-assisted steam flooding

A review of the mechanics of heavy-oil recovery by steam injection with chemical additives

In this paper, extraheavy oil recovery assisted by CO2 and an oil-soluble viscosity reducer under deep reservoir conditions was experimentally investigated. Specifically, the viscosity reduction efficiency of the oil-soluble viscosity reducer was measured, and the morphological characteristics of the asphaltenes in the heavy oil were observed by scanning electron microscopy (SEM) and atomic force microscopy (AFM). CO2 huff-n-puff experiments were carried out to determine the oil recovery factor and the oil/gas exchange ratio. The properties of the produced oil were tested, and the oil saturation in cores was scanned through nuclear magnetic resonance (NMR). The experimental results show that the oil-soluble viscosity reducer decreases the viscosity of extraheavy oil by decreasing the asphaltene concentration and the size of the asphaltene aggregations in the extraheavy oil. CO2 huff-n-puff assisted by an oil-soluble viscosity reducer can considerably improve the oil recovery of extraheavy oil. When the concentration of the viscosity reducer increases from 0 to 10 wt%, the oil recovery factor after five cycles increases from 18.74 % to 34.44 %, and the foamy oil effect is stimulated. An economic concentration range of 1–3 wt% is suggested for field CO2 huff-n-puff applications. With increasing CO2 huff-n-puff cycles, the cyclic oil recovery factor and oil/gas exchange ratio sharply decrease. The oil recovery and oil/gas exchange ratio of the first two cycles are considerably higher than those of the last three cycles. The oil saturation tested by NMR shows that the sweep area of CO2 huff-n-puff is limited to the first two-thirds of the core, indicating that the injection volume of CO2 should be increased with each successive cycle, and the well distance should be suitably decreased to improve the oil recovery of the whole reservoir.

New insight into CO2 huff-n-puff process for extraheavy oil recovery via viscosity reducer agents: An experimental study

The invention relates to a method for improving the ordinary heavy oil reservoir recovery ratio by adopting chemical agents to assist CO2 huff and puff. The method is characterized by combining the chemical agents with CO2 huff and puff, firstly injecting a viscosity reducer or foaming agent type chemical agent solution slug into an oil well undergoing multiple rounds of CO2 huff and puff, later injecting a high pressure CO2 slug into the well and carrying out soaking after injection is completed. The method has the advantages that during soaking, the viscosity reducer type chemical agents and the ordinary heavy oil form oil-in-water type emulsion, thus substantially reducing the oil-water interfacial tension and reducing the crude oil flow resistance during exploitation; the CO2 gas phase mobility can be controlled and CO2 can be effectively prevented from gas channeling through addition of the foaming agent type chemical agents, so that CO2 diffuses toward the depth of the stratum and the CO2 wave and volume are increased; and due to synergy of the chemical agents and CO2, the oil well can still maintain higher oil production after multiple rounds of huff and puff.

Method for improving ordinary heavy oil reservoir recovery ratio by adopting chemical agents to assist CO2 huff and puff

Steam injection is an important process for the thermal recovery of heavy oil reservoirs. As a non-condensable gas (NCG), CO2-assisted steam injection can not only improve the development effect but also reduce carbon emissions. In this study, the simulation method was combined with the experimental method. Based on an experiment using steam condensation with or without CO2, the influence of the condensation mode on steam heat transfer was considered. The effect of changes in the steam flow rate on phase transition and steam quality were analysed. The heat transfer effects of the gas-steam mixture with different contents of CO2 were compared. The results show that the surface condensation mode changes from dropwise condensation to film condensation with the addition of CO2, and the average temperature of the condensation block decreases by 20.05%. With increases in the steam flow rate, the quality of steam increases, and the heat transfer coefficient of steam on the condensation surface increases. With increase in CO2 content, the temperature of the gas-steam mixture decreases, and the inhibition effect on steam heat transfer is more obvious.

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Mingxuan Wu

Papers

Microscopic visualization of greenhouse-gases induced foamy emulsions in recovering unconventional petroleum fluids with viscosity additives

New insight into CO2 huff-n-puff process for extraheavy oil recovery via viscosity reducer agents: An experimental study

Method for improving ordinary heavy oil reservoir recovery ratio by adopting chemical agents to assist CO2 huff and puff

Investigation of the Heat Transfer Mechanism of CO2-Assisted Steam Injection via Experimental and Simulation Evaluation