A Literature Review of CO2, Natural Gas, and Water-Based Fluids for Enhanced Oil Recovery in Unconventional Reservoirs
TL;DR: In this paper, the development of an economically viable enhanced oil recovery (EOR) techni cation is discussed, which is typically less than 10% of the primary primary oil recovery from fractured unconventional formations, such as shale or tight sands.
Abstract: Primary oil recovery from fractured unconventional formations, such as shale or tight sands, is typically less than 10%. The development of an economically viable enhanced oil recovery (EOR) techni...
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TL;DR: In this article, the profound impact of crucial parameters such as temperature, pressure, carbon dioxide soaking time, and core stimulation on the oil recovery enhancement were investigated, and the considerable influence of pressure and temperature on the carbon dioxide adsorption capacity storage were performed and analyzed.
116 citations
TL;DR: The use of polymers and nanoparticles with CO2 flooding is relatively new as mentioned in this paper and is mostly investigated experimentally, at the laboratory level, and they still need further development prior to field implementation.
38 citations
TL;DR: In this article , the advantages and disadvantages of the techniques used for injecting CO2 into subsurface reservoirs and the methods adopted in attempts to control CO2 mobility are reviewed and the potential to improve CO2 flooding techniques and the challenges and uncertainties associated with achieving that objective are addressed.
Abstract: Carbon dioxide (CO2) in enhanced oil recovery (EOR) has received significant attention due to its potential to increase ultimate recovery from mature conventional oil reserves. CO2-enhanced oil recovery (CO2-EOR) helps to reduce global greenhouse gas emissions by sequestering CO2 in subterranean geological formations. CO2-EOR has been exploited commercially over recent decades to improve recovery from light and medium gravity oil reservoirs in their later stages of development. CO2 tends to be used in either continuous flooding or alternated flooding with water injection. Problems can arise in CO2-flooded heterogeneous reservoirs, due to differential mobility of the fluid phases, causing viscous fingering and early CO2 penetration to develop. This study reviews the advantages and disadvantages of the techniques used for injecting CO2 into subsurface reservoirs and the methods adopted in attempts to control CO2 mobility. Recently developed methods are leading to improvements in CO2-EOR results. In particular, the involvement of nanoparticles combined with surfactants can act to stabilize CO2 foam, making it more effective in the reservoir from an EOR perspective. The potential to improve CO2 flooding techniques and the challenges and uncertainties associated with achieving that objective are addressed.
33 citations
TL;DR: In this paper, the behavioral mechanism of gas injection for the development of deep oil reservoirs was investigated through molecular dynamic simulation, with the response to environment taken as the critical influencing factor in EOR.
31 citations
TL;DR: In this article, the authors proposed to use ethanol as a co-solvent to promote the solubilities of four different surfactants (NP-9, 2EH-PO5-EO9, AOT, and TXIB) in CO2.
27 citations
References
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TL;DR: In this paper, a pore classification consisting of three major matrix-related pore types is presented that can be used to quantify matrix related pore and relate them to pore networks.
Abstract: Matrix-related pore networks in mudrocks are composed of nanometer- to micrometer-size pores. In shale-gas systems, these pores, along with natural fractures, form the flow-path (permeability) network that allows flow of gas from the mudrock to induced fractures during production. A pore classification consisting of three major matrix-related pore types is presented that can be used to quantify matrix-related pores and relate them to pore networks. Two pore types are associated with the mineral matrix; the third pore type is associated with organic matter (OM). Fracture pores are not controlled by individual matrix particles and are not part of this classification. Pores associated with mineral particles can be subdivided into interparticle (interP) pores that are found between particles and crystals and intraparticle (intraP) pores that are located within particles. Organic-matter pores are intraP pores located within OM. Interparticle mineral pores have a higher probability of being part of an effective pore network than intraP mineral pores because they are more likely to be interconnected. Although they are intraP, OM pores are also likely to be part of an interconnected network because of the interconnectivity of OM particles. In unlithifed near-surface muds, pores consist of interP and intraP pores, and as the muds are buried, they compact and lithify. During the compaction process, a large number of interP and intraP pores are destroyed, especially in ductile grain-rich muds. Compaction can decrease the pore volume up to 88% by several kilometers of burial. At the onset of hydrocarbon thermal maturation, OM pores are created in kerogen. At depth, dissolution of chemically unstable particles can create additional moldic intraP pores.
1,895 citations
TL;DR: Pore-throat sizes in siliciclastic rocks form a continuum from the submillimeter to the nanometer scale as mentioned in this paper, which provides a useful perspective for considering the emplacement of petroleum in consolidated siliclastics and fluid flow through fine-grained source rocks now being exploited as reservoirs.
Abstract: Pore-throat sizes in siliciclastic rocks form a continuum from the submillimeter to the nanometer scale. That continuum is documented in this article using previously published data on the pore and pore-throat sizes of conventional reservoir rocks, tight-gas sandstones, and shales. For measures of central tendency(mean,mode,median),pore-throatsizes(diameters) are generally greater than2 mm in conventionalreservoir rocks, range from about 2 to 0.03 mm in tight-gas sandstones, and rangefrom0.1to0.005 mminshales.Hydrocarbonmolecules, asphaltenes, ring structures, paraffins, and methane, form another continuum, ranging from 100 A ˚ (0.01 mm) for asphaltenes to 3.8 A ˚ (0.00038 mm) for methane. The pore-throat size continuum provides a useful perspective for considering (1) the emplacement of petroleum in consolidated siliciclastics and (2) fluid flow through fine-grained source rocks now being exploited as reservoirs.
1,083 citations
TL;DR: In this paper, a single reservoir sandstone core was tested with repeated waterfloods and it was shown that potentially mobile fine particles play a key role in the sensitivity of oil recovery to salinity.
966 citations
TL;DR: Video microscopy is used to demonstrate both the two-dimensional crystal-like ordering of charged nanometre-sized polystyrene spheres in water, and the enhanced spreading dynamics of a micellar fluid, at the three-phase contact region, which suggest a new mechanism for oily soil removal—detergency.
Abstract: Suspensions of nanometre-sized particles (nanofluids) are used in a variety of technological contexts. For example, their spreading and adhesion behaviour on solid surfaces can yield materials with desirable structural and optical properties1. Similarly, the spreading behaviour of nanofluids containing surfactant micelles has implications for soil remediation, oily soil removal, lubrication and enhanced oil recovery. But the well-established concepts of spreading and adhesion of simple liquids do not apply to nanofluids2,3,4,5,6,7. Theoretical investigations have suggested that a solid-like ordering of suspended spheres will occur in the confined three-phase contact region at the edge of the spreading fluid, becoming more disordered and fluid-like towards the bulk phase8,9. Calculations have also suggested that the pressure arising from such colloidal ordering in the confined region will enhance the spreading behaviour of nanofluids10,11. Here we use video microscopy to demonstrate both the two-dimensional crystal-like ordering of charged nanometre-sized polystyrene spheres in water, and the enhanced spreading dynamics of a micellar fluid, at the three-phase contact region. Our findings suggest a new mechanism for oily soil removal—detergency.
785 citations