Special Issue "Enhanced Oil Recovery 2020"

A special issue of Energies (ISSN 1996-1073). This special issue belongs to the section "Geo-Energy".

Deadline for manuscript submissions: 31 May 2020.

Special Issue Editor

Prof. Dr. Dandina N. Rao
E-Mail Website
Guest Editor
Craft & Hawkins Department of Petroleum Engineering, Louisiana State University, Baton Rouge, LA 70803, USA
Interests: enhanced oil recovery; gas-assisted gravity drainage; wettability; miscibility

Special Issue Information

Dear Colleagues,

In addition to being a source of energy, crude oil is the basic raw material for innumerable products that we use every day. Even when the alternate sources of energy, such as solar and wind power, become competitive, they will never be able to serve as raw material for these petrochemical products, which range from perfumes to insecticides and fertilizers, and eyeglasses to heart valves. Hence, the world will continue to depend on crude oil for the foreseeable future. However, where will this crude oil come from to meet this ever-increasing demand? Enhanced oil recovery (EOR) is the answer. Therefore, this Special Issue is dedicated to the topic of EOR.

The target for EOR is over 407 billion barrels in onshore US reservoirs and over 2 trillion barrels around the world. It is known that an increase in the capillary number by four orders of magnitude or more is required of any EOR process to reduce the residual oil saturation significantly below that of a waterflood.

The literature has established ways to accomplish such a large change in capillary number in the producing reservoirs by means of reducing the interfacial tension and by altering wettability. Both these aspects have been explored through several research studies using surfactants and recently through low-salinity waterflooding.

Thermal EOR has to overcome the economic challenges of producing relatively lower-priced heavy oil using an expensive injectant (such as steam). Novel techniques of downhole steam generation and comingling steam with additives are being attempted to bring down the costs.

Shale oil is the new big story of this decade. Although they have played a significant role in setting the new energy scene in the world, shale oil resources direly require EOR technologies, since their primary production rates drop rapidly in the first few years, with reported recoveries only in the range of 3–7% OOIP.

This Special Issue on EOR-2020 aims to address all the above resources by bringing together the knowledge and experience of experts in various disciplines in this one volume.

Prof. Dr. Dandina N. Rao
Guest Editor

Manuscript Submission Information

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Keywords

  • enhanced oil recovery
  • crude oil
  • waterflood
  • surfactants
  • thermal EOR

Published Papers (5 papers)

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Research

Open AccessArticle
A Novel Assisted Gas–Oil Countercurrent EOR Technique for Attic Oil in Fault-Block Reservoirs
Energies 2020, 13(2), 402; https://doi.org/10.3390/en13020402 - 14 Jan 2020
Abstract
As the mature oil fields have stepped into the high water cut stage, the remaining oil is considered as potential reserves, especially the attic oil in the inclined fault-block reservoirs. A novel assisted gas–oil countercurrent technique utilizing gas oil countercurrent (GOC) and water [...] Read more.
As the mature oil fields have stepped into the high water cut stage, the remaining oil is considered as potential reserves, especially the attic oil in the inclined fault-block reservoirs. A novel assisted gas–oil countercurrent technique utilizing gas oil countercurrent (GOC) and water flooding assistance (WFA) is proposed in this study to enhance the remaining oil recovery in sealed fault-block reservoirs. WFA is applied in our model to accelerate the countercurrent process and inhibit the gas channeling during the production process. Four comparative experiments are conducted to illustrate enhanced oil recovery (EOR) mechanisms and compare the production efficiency of assisted GOC under different assistance conditions. The results show that WFA has different functions at different stages of the development process. In the gas injection process, WFA forces the injected gas to migrate upward and shortens the shut-in time by approximately 50% and the production efficiency improves accordingly. Compared with the basic GOC process, the attic oil swept area is extended 60% at the same shut-in time condition and secondary gas cap forms under the influence of WFA. At the production stage, the WFA and secondary gas cap expansion form the bi-directional flooding. The bi-directional flooding also displaces the bypassed oil and replaced attic oil located below the production well, which cannot be swept by the gas cap expansion. WFA inhibits the gas channeling effectively and increases the sweep factor by 26.14% in the production stage. The oil production increases nearly nine times compared with the basic GOC production process. The proposed technique is significant for the development of attic oil in the mature oil field at the high water cut stage. Full article
(This article belongs to the Special Issue Enhanced Oil Recovery 2020)
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Open AccessArticle
Performance Evaluation of an Anti Gas-Channeling System (Asphalt-Rigid Particle-Xanthan Gum) Applied in High-Temperature and High-Salinity Fractured Reservoir
Energies 2019, 12(24), 4766; https://doi.org/10.3390/en12244766 - 13 Dec 2019
Abstract
Asphalt and rigid particles have been chosen as the main blocking agent for solving the anti gas-channeling in high-temperature and high-salinity reservoirs. Particle size range and the concentration of suspending agent were firstly determined, and the influence factors on bonding effect between two [...] Read more.
Asphalt and rigid particles have been chosen as the main blocking agent for solving the anti gas-channeling in high-temperature and high-salinity reservoirs. Particle size range and the concentration of suspending agent were firstly determined, and the influence factors on bonding effect between two materials in the high-temperature environment were then studied. An orthogonal experiment involving three factors (the content of rigid particles and asphalt, and softening point) and four levels was designed to investigate the impact order of the three factors on anti gas-channeling performance, and the optimization scheme has been identified. Results showed that the importance sequence of the factors was C rigid particles > C asphalt > softening point. By verifying the optimization scheme, the plugging ratio of this agent can reach more than 86.24% for 2 mm fractured core in high-temperature and high-salinity environments. The system was evenly distributed in the internal fractures, occupied the fractures completely, and had a certain height of accumulation. The micromorphology observations of the optimal scheme showed that the softened asphalt demonstrated its ‘amoeba’ characteristic and bonded with the surrounding rigid particles. The asphalt filled in the pore which was formed by bridging rigid particles to guarantee the blocking layer did not collapse or was carried by high-pressure N2-flow. This approach can potentially solve gas-channeling problems in reservoirs with serious environments. Full article
(This article belongs to the Special Issue Enhanced Oil Recovery 2020)
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Open AccessArticle
Optimization Design of Injection Strategy for Surfactant-Polymer Flooding Process in Heterogeneous Reservoir under Low Oil Prices
Energies 2019, 12(19), 3789; https://doi.org/10.3390/en12193789 - 07 Oct 2019
Abstract
Surfactant–polymer (SP) flooding has significant potential to enhance oil recovery after water flooding in mature reservoirs. However, the economic benefit of the SP flooding process is unsatisfactory under low oil prices. Thus, it is necessary to reduce the chemical costs and improve SP [...] Read more.
Surfactant–polymer (SP) flooding has significant potential to enhance oil recovery after water flooding in mature reservoirs. However, the economic benefit of the SP flooding process is unsatisfactory under low oil prices. Thus, it is necessary to reduce the chemical costs and improve SP flooding efficiency to make SP flooding more profitable. Our goal was to maximize the incremental oil recovery of the SP flooding process after water flooding by using the equal chemical consumption cost to ensure the economic viability of the SP flooding process. Thus, a systematic study was carried out to investigate the SP flooding process under different injection strategies by conducting parallel sand pack flooding experiments to optimize the SP flooding design. Then, the comparison of the remaining oil distribution after water flooding and SP flooding under different injection strategies was studied. The results demonstrate that the EOR efficiency of the SP flooding process under the alternating injection of polymer and surfactant–polymer (PASP) is higher than that of conventional simultaneous injection of surfactant and polymer. Moreover, as the alternating cycle increases, the incremental oil recovery increases. Based on the analysis of fractional flow, incremental oil recovery, and remaining oil distribution when compared with the conventional simultaneous injection of surfactant and polymer, the alternating injection of polymer and surfactant–polymer (PASP) showed better sweep efficiency improvement and recovered more remaining oil trapped in the low permeability zone. Thus, these findings could provide insights into designing the SP flooding process under low oil prices. Full article
(This article belongs to the Special Issue Enhanced Oil Recovery 2020)
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Open AccessArticle
Polymer Gels Made with Functionalized Organo-Silica Nanomaterials for Conformance Control
Energies 2019, 12(19), 3758; https://doi.org/10.3390/en12193758 - 30 Sep 2019
Abstract
Deep placement of gel in waterflooded hydrocarbon reservoirs may block channels with high water flow and may divert the water into other parts of the reservoir, resulting in higher oil production. In order to get the gel constituents to the right reservoir depths, [...] Read more.
Deep placement of gel in waterflooded hydrocarbon reservoirs may block channels with high water flow and may divert the water into other parts of the reservoir, resulting in higher oil production. In order to get the gel constituents to the right reservoir depths, a delay in the gelling time in the order of weeks at elevated temperatures will be necessary. In this work, a methodology for controlled gelation of partially hydrolyzed polyacrylamide using hybrid nanomaterials with functional groups as cross-linkers was developed. Two delay mechanisms with hybrid materials and polyelectrolyte complexes were designed and tested. Both mechanisms could significantly delay the gelation rate, giving gelling times ranging from several days to several weeks in synthetic sea water at 80 °C. Gelling experiments in sandstone cores showed that gel strength increased with aging time. For long aging times, strong gels were formed which resulted in almost no water permeability. A series of coreflooding experiments with polymer and deactivated nanomaterial were performed. In addition to differential pressures and concentration profiles, the experiments enabled calculation of retention and inaccessible pore volumes. A novel numerical model of 1D two-phase flow has been developed and tested with results from core flooding experiments. The model can track the age distribution and concentrations of the nanomaterial (and therefore water viscosity) throughout the porous medium at every time step. The model generated a good fit of experimental results. Full article
(This article belongs to the Special Issue Enhanced Oil Recovery 2020)
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Open AccessArticle
Morphology and Rheological Properties of Polyacrylamide/Bentonite Organic Crosslinking Composite Gel
Energies 2019, 12(19), 3648; https://doi.org/10.3390/en12193648 - 24 Sep 2019
Abstract
The use of polymer gel for water control and oil addition is a common technical method in oilfield development. The polymer and hydrated bentonite react under the action of an organic crosslinking agent to form a composite gel. The particle-size change and microstructure [...] Read more.
The use of polymer gel for water control and oil addition is a common technical method in oilfield development. The polymer and hydrated bentonite react under the action of an organic crosslinking agent to form a composite gel. The particle-size change and microstructure of the composite gel were analyzed via shear thinning, thixotropic, viscoelastic, and start-up stress rheology experiments. The experimental results show that the polyacrylamide/bentonite organic crosslinked composite gel was a gel system with bentonite as the core aggregate structure, and the large particle-size distribution was mostly increased with increasing crosslinker content. The composite gel presented shear thinning characteristics, the content of bentonite or crosslinking agent was increased, and the shear resistance was stronger at a high shear rate. The composite gel exhibited positive thixotropic properties, and the thixotropy increased with increasing bentonite content. The composite gel had good viscoelastic characteristics, the elastic characteristics of the composite gel showed more significantly with bentonite increases, and the viscosity of the composite gel showed its characteristics more significantly with the crosslinking agent increased. After loading at a rate on the composite gel, the shear stress increased significantly with time and reached its maximum value, and then the shear stress decreased and gradually stabilized. Full article
(This article belongs to the Special Issue Enhanced Oil Recovery 2020)
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