In order to explore the impact of various flood schemes and pore throat heterogeneity on oil recovery efficiency in porous media, core-flood experiments nuclear magnetic resonance (NMR) tests are conducted quantitatively determine initial distribution residual medium-to-high-permeability cores subjected these schemes. Multiple experimental runs with four field core samples cover schemes: secondary water flood, CO2-foam water-alternating-CO2 (WAG). Experimental results show that, relatively...

Reservoir pressure is a key factor affecting the degree of spontaneous imbibition. In this work, oil distribution characteristics in core samples were simulated before and after imbibition using nuclear magnetic resonance (NMR) technology. Specifically, four selected subjected to experiments at 0.1, 5, 10, 15 MPa, respectively. Furthermore, efficiency rate different pressures can be quantitatively calculated NMR T2 spectrum. The results indicate that smaller larger pores has no obvious trend...

The fracturing fluid residing in a reservoir undergoes spontaneous imbibition. Here, to explore the mechanism of imbibition and oil displacement, experiments on under different influencing factors were conducted core sample from Ordos Basin Chang 8 formation. Combined with nuclear magnetic resonance technology, we quantitatively evaluated degree production pores during displacement process. Experimental results show that salinity, interfacial tension, crude viscosity are negatively...

With nuclear magnetic resonance (NMR), a novel experimental study is conducted to reveal the pore-scale formation damage mechanism of tight sandstones caused by asphaltene precipitation during CO₂ flooding.

Water flooding is widely used for recovering crude oil from unconventional reservoirs due to its economic feasibility. At reservoir conditions, the injected water usually imbibed into fractured rocks, so-called spontaneous imbibition, providing a considerable driving force enhancing recovery. In this work, imbibition on rock surface investigated at high-pressure and influence tight recovery revealed pore-scale perspective. Specifically, three typical core samples are selected characterized...

In the CO2 flooding stage of tight sandstone reservoirs, CO2-crude oil-rock interaction causes asphaltene deposition and mineral dissolution effect, which would affect reservoir performance physical property. To reveal variation law percolation capacity in stage, core samples typical reservoirs with different permeability levels were selected. An indoor flow simulation experiment was then performed. The change characteristics quantitatively evaluated, evolution macroscopic seepage ability...

Gas shale has shown considerable force in gas production worldwide, but little attention been paid to its electrical properties, which are essential for reservoir evaluation and differentiating absorbed free gas. In this study, experiments designed research water saturation establishment methods properties of shale. Nuclear magnetic resonance (NMR) with short echo space (TE) is used identify distribution saturated pores contribute the conductivity. The experimental results indicate that NMR...

The microscopic pore structure of tight sandstone reservoir significantly influences the characteris-tics CO2 flooding after water flooding. research was conducted using various techniques such as casting thin sections, high pressure mercury injection, scanning electron microscopy, Nu-clear magnetic resonance (NMR) testing, and a self-designed high-temperatures high-pressures visualization displacement system. Three type cores with different structures were selected for experiments...

Water huff-n-puff is considered to be an available method exploit unconventional oil reservoirs, which can significantly promote the reservoir pressure and facilitate water–oil exchange under imbibition effect. To explore production characteristics well performance during water in Huanjiang field that a tight reservoir, tests were carried out performances investigated. Moreover, simulation works conducted study various factors influence performance. Furthermore, sensitivity analysis for was...

CO2 injection is an effective way to improve oil recovery for tight sandstone reservoirs. In this study, the cores collected from Chang 6 Member of Yanchang Formation in Ordos Basin underwent continuous flooding, and huff puff displacement measurements were under five various pressures, 4, 8, 12, 16, 20 MPa respectively; combined with classification pores cores, differences producing degree varying scale discussed detail. Under reaches up 73.29%, while features a higher degree, it almost...

An experimental technique is developed to investigate the dynamic imbibition displacement mechanism in tight sandstone formations of Yanchang group Ordos basin. By combining core flooding experiments and NMR technique, effects injection volume rate on efficiency are investigated. Moreover, compared with that static imbibition. This study gains insights into micromechanisms formations. It found relative increases increase volume. But increment amplitude decreases With same volume, high...

This study aims to investigate the impact of CO2 huff-n-puff after flooding on recovery efficiency in tight sandstone reservoirs. The experimental methodology involved selection three representative cores with different permeability levels emulate class I, II, and III To examine immiscible, nearly miscible, miscible conditions for reservoir samples, a physical simulation flow system integrated nuclear magnetic resonance technology was employed. performed followed by experiments at five...

The microscopic pore structure of tight sandstone reservoirs significantly impacts CO2 flooding characteristics. In this work, two types realistic visualization models were selected based on petrophysical properties and the feature. experiments under different injection pressures volumes carried out using in-house high-temperature -pressure system. Then, characteristics oil movement residual distribution quantitatively described analyzed for rock types. results show that type I model has...

The recoverable hydrocarbon reserves of conventional oil and gas resources are very limited in China. As important alternative resources, unconventional have become a research hotspot. Though tight reservoirs great potential to alleviate the increasing demand, issues during development process, such as rapid pressure depletion, fast decline production, low productivity, difficulties water injection, usually encountered due poor physical properties like small pore throats strong heterogeneity...

The microscopic pore structure of tight sandstone reservoirs significantly influences the characteristics CO2 flooding after water flooding. This research was conducted using various techniques such as casting thin sections, high-pressure mercury injection, scanning electron microscopy, nuclear magnetic resonance (NMR) testing, and a self-designed high-temperature visualization displacement system. Three types cores with different structures were selected for experiments experiments,...

Summary The color-gradient lattice Boltzmann (LB) method is used to investigate the inertial effect on oil/water countercurrent imbibition characteristics in a matrix-fracture system. interplay between capillarity, fluid inertia, and viscous force during under different viscosity ratios delineated. Pore-scale dynamics, interfacial front morphology, oil recovery influence of inertia are also elucidated. Additionally, we study energy conversion displacement from perspective balance. Finally,...

CO2 flooding is an effective way in the tertiary oil recovery. While asphaltene often precipitates from crude during flooding, and mechanisms of blockage resulting precipitation still unclear different schemes. In this work, pure-CO2 water-alternating-CO2 (WAG), CO2-foam were applied to conduct core-flooding experiments. Then, as for each scheme, we quantitatively investigated degree pores due with nuclear magnetic resonance (NMR) technique. Tests results show that has a relatively higher...