In situ upgrading of heavy oil by catalytic hydrogenation using submicrometer sized dispersed catalysts during thermal recovery is a promising new idea to achieve an environmentally sustainable method for unlocking heavy oil and bitumen resources. This requires placement of the ultradispersed catalyst particles deep into the formation where it can accelerate the high-temperature upgrading reactions. The objective of this work was to investigate the feasibility of transporting such ultradispersed catalyst particles through porous rock formations. This paper presents the results of experiments carried out to systematically examine the propagation of ultradispersed catalyst suspensions in sand packs. These experiments involved the injection of submicrometer-sized catalyst particles suspended in oil into a sand pack and analysis of the produced fluid samples and the sand bed. The results show that it is possible to propagate the ultradispersed catalyst suspension through sand beds. However, a fraction of the catalyst particles are retained by the sand (around 14 to 18%), and much higher retention occurs in the entrance region of the bed. Particles appear to be deposited on sand surfaces by an attachment mechanism deep inside the bed, but larger particles appear to be strained by mechanical trapping near the inlet face. The deposition of particles was found to be almost irreversible in the sense that the deposited particles could not be remobilized by reverse flow of the suspending medium.
The proposed in situ catalytic upgrading of heavy oil to achieve an environmentally sustainable method for heavy oil recovery requires the placement of nanodispersed catalyst particles deep into the formation where it can accelerate the high‐temperature upgrading reactions. In continuation of the previous work [Zamani et al., Energy Fuels 24, 4980‐4988 (2010)], this paper presents results of several new experiments carried out to examine the effects of other parameters, including the connate brine salinity, absolute permeability, sand‐bed temperature and particle concentration on the propagation of nanoparticles in porous media. The results show that lower permeability, increased operating temperature and higher particle concentration did not significantly affect the propagation of nanodispersed catalyst suspension through the sand‐bed. Virtually the same filtration behaviour, displaying a rapid increase of effluent concentration at 1 pore volume injected to a steady concentration close to the inlet concentration was seen in all experiments. A classical phenomenological approach was used to model the macroscopic propagation behaviour of suspended particles in the porous medium. The model was successful in history matching the effluent composition profile observed in the experiments and the deposition profile obtained from post‐test analysis of the sand‐bed. © 2011 Canadian Society for Chemical Engineering
This paper presents results of an experimental study that systematically examined the propagation of nanodispersed catalyst suspension in sandpacks prepared with Athabasca reservoir sand and operated at the reservoir conditions. The concentration and size distribution of the particles at the injection and production end were measured. The pressure drops in different segments along length of the sandpack were monitored continuously. The retention behaviour of particles at the end of each experiment was examined by measuring the catalyst concentration in the bed as a function of the distance from the injection end of the sandpack and also by analysis of extracted samples using scanning electron microscopy.The results show that it is possible to propagate the nanodispersed catalyst suspension through sand beds without causing permeability damage, but a small fraction of the injected particles is retained in the sand. It was found that significantly higher retention occurs in the entrance region of the bed (compared with downstream regions) and that the total particle retention was higher in the Athabasca sand beds than in clean silica sand with the same flow and suspension properties.To the best of our knowledge, this is the first experimental study on transport of nanoparticles dispersed in viscous oil through reservoir sand beds. It provides valuable information on propagation and retention behaviour of nanoparticles. Considering the rapidly rising use of nanoparticles in industry, such transport will be encountered in numerous industrial applications and environmental problems.
This paper presents results of an experimental study that systematically examined the propagation of nanodispersed catalyst suspension in sand packs at Athabasca reservoir conditions. The concentration and size distribution of the particles at the injection and production end were measured. The pressure drops in different segments along length of the sand pack were monitored continuously. The retention behavior of particles at the end of each experiment was examined by measuring the catalyst concentration in the bed as a function of the distance from injection end of the sand pack and also by analysis of extracted samples using scanning electron microscopy. This research is a part of a large multidisciplinary effort aimed at developing a nanoparticles based process for in situ upgrading of heavy oil by catalytic hydrogenation during thermal recovery processes. An essential element of such in situ upgrading is the placement of nanodispersed catalyst particles deep into the formation where it can accelerate the high temperature upgrading reactions. Therefore, an understanding of the propagation behavior of nanoparticles in reservoir sand is essential for developing such technology. The results of this work would also be useful for modeling any other process involving transport of nanoparticles through porous media. The results show that it is possible to propagate the nanodispersed catalyst suspension through sand beds without causing permeability damage but a small fraction of the injected particles are retained in the sand. It was found that much higher retention occurs in the entrance region of the bed and such retention was higher in the Athabasca sand beds than in clean silica sand with the same flow and suspension properties. A modified deep bed filtration model was developed to history match the macroscopic propagation behavior of suspended particles in sand beds. To best of our knowledge, this is the first experimental study on transport of nanoparticles dispersed in viscous oil through sand beds. It provides valuable information on propagation and retention behavior of nanoparticles. Considering the rapidly rising use of nanoparticles in industry, such transport will be encountered in many industrial applications and environmental problems.
One of the major problems faced in steam assisted gravity drainage (SAGD) development is monitoring steam chamber growth and conformance in a cost-effective way. Currently, this is primarily done using 4D seismic. However, each survey costs several million dollars, can generally be taken once a year in winter, and is limited in resolution. This paper investigates the use of pressure transient analysis (PTA) to monitor steam chamber conformance as a low-cost and on-demand alternative. While PTA has been widely and successfully used in the conventional oil and gas industry, there has been little application to SAGD. A range of cases were investigated using reservoir simulation including steam flooding in a vertical well, 2D homogeneous and 3D heterogeneous SAGD cases. The heterogeneous cases included variations in permeability and shale layers along the injector. Pressure responses from different pressure gauge configurations such as a single gauge and multiple gauges along the injector were analyzed. Results indicate that PTA can estimate total chamber pore volume reasonably accurately, despite a number of non-ideal conditions such as heterogeneity in saturations and countercurrent flow. Results also indicate that PTA potentially can be used in a number of ways to monitor steam chamber growth. First, changes in total steam chamber volume potentially can be monitored by observing changes in pseudo-steady state behavior (PSS) over time. More importantly, the character of the derivative plot changes with the maturity/shape of the chamber, indicating that the derivative plot can be used as a qualitative tool for monitoring steam chamber growth. In particular, the derivative behavior at a pressure gauge is governed largely by local steam chamber conditions near the gauge so that multiple gauges down the horizontal section can be used to monitor how different parts of the steam chamber are growing. However, there are limitations on what can be discriminated; differences in chamber shape have to be major for the derivative responses to be significantly different.
Water-saturated lean zones are notoriously challenging for steam-assisted gravity drainage (SAGD) operations since they increase heat loss and impair the SAGD performance. This study proposes mitigating lean zone effects using gas/water displacement to reduce lean zone impacts and improve SAGD performance. At the beginning of this study, we conduct a literature review on lean zones and gas-water displacement. We then develop a three-dimensional homogenous model to simulate SAGD scenarios with and without lean zone mitigation (LZM). Our findings reveal that lean zones have negative effects on SAGD performance, mostly owing to the pressure imbalance between lean and rich zones, which causes steam channelling and energy loss. LZM demonstrates significant advantages of using non-condensable gases (NCG) to displace water and balance pressure between the rich and lean zones, hence minimizing steam channelling and saving energy.
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