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In-situ produced nanoparticles for enhanced oil recovery

Periodic Reporting for period 4 - iNanoEOR (In-situ produced nanoparticles for enhanced oil recovery)

Reporting period: 2020-02-01 to 2021-07-31

The global demand of energy is expected to increase as much as 50% in the next 20 years and the demand for oil and gas will also increase. The era of finding “easy oil” is coming to an end, and future supply will become more reliant on fossil fuels produced from non-conventional reservoirs and from enhanced oil recovery (EOR) process. Oil and gas are contained in rocks, i.e. porous media connected with different pores linked through pore-throats, and are generally produced in three stages: primary, secondary, and tertiary. For every barrel of oil we used today, there are still two barrels in the existing reservoir trapped in reservoir rocks. The development of new technologies for EOR from a particular well becomes increasingly important.
Nanotechnology may provide an alternative solution, where the fundamental question is about nanoparticles (NPs): their functionality and mobility control in the complex reservoir condition. Comparing the exiting EOR technologies, injecting NPs together with flooding fluids could have many advantages, and can be used as ‘contrast’ to provide better reservoir characterisation, for controlled delivery of chemicals, and for conformance control to increase the oil recovery rate. This project proposed and validated a revolutionary idea: in-situ production of NPs inside the reservoir for enhanced oil recovery, termed as iNanoEOR. Rather than pre-manufacturing and stabilizing NPs in advance, which had serious problems of flowing through the reservoir, NPs are proposed to be produced inside the reservoir by controlled reactions. It was shown that NPs can be used as sensors to improve reservoir characterization, or controlled delivery agency to improve oil recovery. Comparing with the current concept, iNanoEOR showed many distinctive advantages, and could bring significant impact to the science, technology and the society.
The aim of this project is to develop and validate an innovative concept by in-situ producing nanomaterials under reservoir-like conditions, and examining the effect of nanomaterials on oil recovery by both numerical and experimental means. Four working packages are arranged to achieve this goal, including WP1 – nanoparticle fabrication and characterisation, WP2- exploring oil removal mechanisms by nanoparticles, WP3-nanoparticle mobility study and WP4-synergies and planning for field study.

The work has been going very well according to the plan. Briefly, different nanomaterials production methods have been studied, and a range of nanomaterials were produced and characterised; rheological, interfacial and morphology properties were obtained, and three flooding systems were established including pore scale, mesoscale and core scale setup. Suitable nanoparticles were identified that could be used for future field test. The major results can be summarized as: 1) The in-situ production and stabilization concept was validated in laboratorial conditions at the pore scale and pore scale. The nanomaterials examined included carbon nanoparticles, metal oxide nanoparticles, and microemulsions under reservoir-like conditions. 2) The effect of nanoparticles on the improved oil recovery and the governing mechanisms of oil recovery were identified. The effect of capillary and viscous forces on the oil mobilization were revealed by both pore-scale experiment and numerical simulation. 3) The mobility of nanoparticles through different samples from pore scale to core scale were examined and the controlling factors on the nanoparticle mobility were revealed. 4) Aiming for future field test, a number of nanoparticles were examined and the right candidate were identified. 5) In addition to the concept of using nanoaprticles directly for enhanced oil recovery, we validated two related novel concepts in core samples, i.e. in-situ production of nanoparticles as potential reservoir sensors, and ii) controlled delivery of chemicals to reduce chemical usage, which represent as two promising results for future take-up. 6) With a similar concept, we extended the application of nanoparticles for soil remediation.

In short summary, all the planned WPs were implemented and the project has been completely satisfactory. These work has resulted in 42 journal papers published over the project period, as detailed in the Publication section. In addition, we presented the work results in 22 conferences, including 3 as the keynote/plenary speaker.
The project is highly innovative with many aspects that go beyond the state-of-art, and the major ones include:
1) Comparing all prior work of using pre-fabricated nanoparticles for enhanced oil, nanoparitcles are produced inside the reservoir by controlled reactions. We have proved that certain nanoparticles can be produced in reservoir-like conditions, and used as sensors to detect oil saturation, or as for stabilizing emulsions. This represent a major advancement of state-of-art
2) We proposed and validated the possibilities of using nanoparticles or nanodroplets as carriers for surfactants that used in tertiary recovery. We proved in the laboratory that using nanodroplets as carriers, the surfactant usage can be largely reduced but with improved oil recovery. This represents another big advancement. More challenging than nanomedicine application, where the pressure and temperature are low during the applications, the controlled delivery for enhanced oil recovery is more demanding considering the porous nature of the rock, the high pressure, high temperature and high salinity harsh environment in the reservoir.
3) We also showed that the concepts of i) in-situ production of nanoparticles for enhancing oil recovery, and ii) controlled delivery of chemicals (surfactant, polymers etc) by using nanoparticles (or in-situ produced nanoparticles) for enhanced oil recovery can be achieved under reservoir-like conditions.
4) Furthermore, we advanced mechanistic understanding of the effects of nanoparticles on interfacial / wettablibity / mobility control, from both microscopic study (molecular simulations) to pore/core scale experimental work.
Innovative concept of in-situ production for upstream oil/gas exploration