Permeability Oil Research Articles

A desert beetle-like mesh membrane by decorating superhydrophilic Fe-doped Cu-MOFs onto superhydrophobic CuC2O4 bowknot-like arrays for boosting water-in-oil emulsion separation

Inspired by the water-collecting mechanism of the back structure of the Stenocara beetle, a novel hierarchical structured mesh membrane was rationally constructed by decorating superhydrophilic Fe-doped Cu-MOFs (HKUST-1) onto superhydrophobic CuC2O4 bowknot-like arrays for enhanced separation of oil-in-water emulsions. The Fe-doped HKUST-1 particles, which accumulated in the mesh pores of the superhydrophobic membrane, served as “water-adsorption” centers to facilitate the capture, aggregation, and adsorption of tiny emulsified water droplets. Moreover, the tight packing of Fe-doped HKUST-1 particles within mesh pores not only significantly reduced the pore size, but also extended the effective range of HKUST-1 particles, thereby enhance the “capture-aggregation” process for emulsified water droplets in oil phases. This rationally-designed mesh membrane was demonstrated to efficiently separate water-in-oil emulsions prepared with different oil types, achieving the highest oil permeation flux of approximately 1200 L·m−2·h−1 and maintaining a water content in the oil phase below 57.0 mg·L−1. This study not only presents a simple and scalable strategy for developing a biomimetic anisotropic superwetting mesh membrane, but also underscores its potential industrial applications in oily wastewater treatment.

Microscopic Remaining Oil Classification Method and Utilization Based on Kinetic Mechanism

In reality, the remaining oil in the ultra-high water cut period is highly dispersed, so a thorough investigation is required to understand the microscopic remaining oil. This will directly influence the technological direction and allow for countermeasures such as enhanced oil recovery (EOR). Therefore, this study aims to investigate the state, classification method and utilization mechanism of the microscopic remaining oil in the late period of the ultra-high water cut. To achieve this, the classification of microscopic remaining oil based on mechanical mechanism was developed using displacement CT scan and micro-scale flow simulation methods. Three carefully selected mechanical characterization parameters were used: oil–water connectivity, oil–mass specific surface and oil–water area ratio. These give five types of microscopic remaining oil, which are as follows: A (capillary and viscous oil cluster type), B (capillary and viscous oil drop type), C (viscous oil film type), D (capillary force control throat type), and E (viscous control blind end type). The state of the microscopic remaining oil in classified oil reservoirs was defined after high-expansion water erosion. Based on micro-flow simulation and analysis of different forces during the displacement process, the main microscopic remaining oil recognized is in class-I, class-II and class-III reservoirs. Within the Eastern sandstone oilfields in China, the ultra-high water-cut stage is a good indicator that the class-I oil layer is dominated by capillary and viscous oil drop types distributed in large connected holes. The class-II oil layer has capillary and viscous force-controlled clusters distributed in small and medium pores with high connectivity. In the case of the class-III oil layer, it enjoys the support of capillary force control throats that are mainly distributed in small holes with high connectivity. Integrating mechanisms of different types of micro-remaining oil indicates that, enhancing utilization conditions requires increasing pressure gradient and shear force while reducing capillary resistance. An effective way to improve the remaining oil utilization is to increase the pressure gradient and change the flow direction during the water-drive development process. Hence, this forms a theoretical basis and a guide for the potential exploitation of remaining oil. Likewise, it provides a strategy for optimizing enhanced oil recovery in the ultra-high water-cut stage of mid-high permeability oil reservoirs worldwide.

Study on characteristics, efficiency, and variations of water flooding in different stages for low permeability oil sandstone

Study on characteristics, efficiency, and variations of water flooding in different stages for low permeability oil sandstone

Mechanism recognition and application effect analysis of air injection development in ultra-low permeability oil reservoirs

Abstract There are few application examples of air drive development technology in ultra-low permeability oil reservoirs in China. The article relies on the air drive development block of H oilfield, and based on the results of core start-up pressure gradient experiment, relative permeability experiment, gas composition experiment, and gas swelling experiment, conducts research and analysis on the seepage mechanism and low-temperature oxidation mechanism of air drive development, demonstrating the advantages of air drive development in oil displacement mechanism of ultra-low permeability oilfield. Based on the basic parameters of oil fields developed by air flooding both domestically and internationally, the specific blocks suitable for air flooding development in H oilfield are selected. The feasibility of conducting air flooding development in low permeability oil fields is demonstrated from three aspects: indoor real core experimental data, safety, and the maturity of existing equipment and technology. At the same time, an analysis is conducted on the development status of the air drive block in H oilfield. By comparing the development effects with adjacent water injection blocks, it is demonstrated that the air drive development effect in ultra-low permeability oilfield is superior to water injection development.

Analytical prediction model for edge water invasion flow rate in SAGD heavy oil reservoirs

SAGD (Steam Assisted Gravity Drainage) technology is a highly developed method for the extracting heavy oil. In the Liaohe Oilfield in China, there are 72 SAGD well groups within a massive heavy oil reservoir containing edge water and the risk associated with edge water invasion is substantial. Currently, the injected steam is less than 50 m away from the edge water, which increases the urgency to address the potential invasion of edge water. If the edge water flows into the reservoir, it will impact nearly 8.0 × 105 tons of crude oil production. Recognizing the importance of mitigating the edge water invasion, this paper proposes a prediction model for the edge water invasion flow rate in SAGD reservoirs. The model integrates mass and heat transfer dynamics between the steam chamber and edge water, the relative permeabilities of oil and water phases, and the viscosity-temperature relationship of water. The model is validated through numerical simulations and field data. The findings indicate that for SAGD reservoirs with a permeability greater than 1 D, maintaining a minimum distance of 25 m between the edge water and the steam chamber is advisable, especially when the pressure differential is 0.5 MPa. Furthermore, the prediction model is used to forecast the edge water breakthrough time and evaluate water invasion risk. A prediction chart for the edge water invasion flow rate is developed, providing a practical tool for estimating invasion flow rate curves. Also, a method of edge water invasion warning is established, with a corresponding chart that offers a quick assessment of water invasion risks in heavy oil reservoirs. Overall, this research lays a foundational framework for understanding and managing the edge water invasion in SAGD operations, offering critical insights for the future study aimed at addressing the challenge posed by edge water in heavy oil reservoirs.

The application of PVC hollow fiber ultrafiltration membrane in ultra-low permeability oilfield

Abstract Oil containing wastewater produced from ultra-low permeability oil fields generally needs to be treated to meet the 5-1-1 standard before it can be reinjected. In order to meet the standards for treating oily wastewater in ultra-low permeability oil fields, PVC hollow fiber ultrafiltration membranes and pre-treatment processes for removing oil, suspended solids, sulfides, etc. before the membrane were selected. The application shows that the aeration air flotation flow sand filtration PVC hollow fiber ultrafiltration membrane process can treat oily wastewater, and the treated water can reach the “5-1-1” standard. In the pre-treatment process of PVC hollow fiber ultrafiltration membrane, the silicone rubber membrane aeration device has good oxidation effect, high efficiency in micro nano air flotation for oil removal and suspended solids, and easy management of sand flow filters. This process has economic feasibility and provides technical support for the treatment of oily wastewater in ultra-low permeability oil fields, with great promotional value.

Experimental Study on the Treatment of Produced Water from Carbon Dioxide Drive by Aeration Method

Abstract To further explore the effective development of produced water treatment technologies suitable for low to ultra-low permeability oil fields, and to clarify the water quality characteristics of produced water from CO2 flooding. A study was conducted on the basic water quality characteristics of produced water from low to ultra-low permeability oil fields. Indoor CO2 gas removal experiments were conducted using the aeration method under 40°C atmospheric pressure conditions. The research results indicate that the CO2 content in the extracted water is one of the important influencing factors for the changes in characteristic parameters such as water pH, mineralization, and corrosion rate; Under the condition of 40°C atmospheric pressure test, the aeration method has a significant treatment effect on the produced water from CO2 flooding, which can effectively remove 70% of the CO2 in the water, thereby improving the pH of the water to 8, and effectively inhibiting the corrosion rate of the produced water below 0.076mm/a.

Bioinspired surface silicification of cellulose-mediated PVDF membranes for significantly enhancing superhydrophilicity and anti-oil adhesion toward ultrafast oil/water emulsion separation

Cellulose is a widely used hydrophilic material due to its rich hydrophilic hydroxyl groups. However, the presence of its lipophilic segment will affect the antifouling performance. Finding strategies to improve this problem has attracted considerable attention. In this work, a layer of silica was applied to a cellulose-deposited polyvinylidene fluoride membrane through a straightforward in-situ bionic silicification process of tetraethyl orthosilicate. The contact angle and oil droplet contact test proved that the high-hydrophilicity and underwater superoleophobicity of the silicified membranes were significantly enhanced. The surface structure and composition were analyzed by scanning electron microscopy, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The results of show that this improvement was mainly attributed to the presence of silicon hydroxyl groups, buried cellulose chains, and micro-nanostructures composed of cellulose and silica. The stable silica coating also provided protection for the polymeric membrane against degradation after water washing for 24 h, ultrasonic treatment (40 KHZ) for 10 min or exposure to different pH levels (pH=1, 4, 9 and 12) and saturated sodium chloride solution for 24 h. Furthermore, the silicified membrane showed outstanding oil adhesion resistance and permeation flux, enabling effective purification of different oil-in-water emulsions that were stabilized by emulsifiers. Notably, the membrane achieved a high oil removal rate (> 99.4 %) of various emulsions (toluene-in-water, cyclohexane-in-water, tetrachloroethane-in-water, soybean oil-in-water, toluene-in-salt solution, toluene-in-acid solution and toluene-in-alkaline solution emulsions). In particular, for toluene-in-water emulsions (oil droplets in the emulsion ranged from 58.77 nm to 615.1 nm), a significantly enhanced permeation flux (4777 L·m−2·h−1·bar−1) was obtained at 0.8 bar pressure. Even after multiple cycles of separation, the flux was higher than that of the unsilicified membrane. Overall, this approach is mild, simple, efficient, and easily scalable, making it an ideal method for producing superhydrophilic coatings with substantial application potential.

Predicting and optimizing CO2 foam performance for enhanced oil recovery: A machine learning approach to foam formulation focusing on apparent viscosity and interfacial tension

Carbon dioxide foam injection stands as a promising method for enhanced oil recovery (EOR) and carbon sequestration. However, accurately predicting its efficiency amidst varying operational conditions and reservoir parameters remains a significant challenge for conventional modeling techniques. This study explores the application of machine learning (ML) methodologies to develop a robust model for matching experimental values in CO2 foam flooding scenarios. Leveraging a comprehensive dataset encompassing diverse surfactants and rock types, with varied porosity and permeability, our model demonstrates accurate predictions across a wide spectrum of conditions. By focusing on key parameters such as foam apparent viscosity, interfacial tension (IFT), injected foam volume, initial oil saturation, porosity, and permeability, we unveil the pivotal role of these factors in determining CO2 foam EOR performance. Through rigorous analysis, we identify the relative importance of each input parameter, with injected foam volume, apparent viscosity, and IFT emerging as dominant factors. The most accurate model was deep neural network (DNN) (R2 value of 0.99). Higher foam viscosity and lower IFT were found to significantly enhance oil recovery rates, though their effects plateau beyond certain thresholds (apparent viscosities above 1200 cP and IFT values below 0.2 mN/m). The findings underscore the potential of ML-driven approaches in enhancing CO2 foam EOR predictions, offering insights crucial for optimizing foam flooding performance across diverse reservoir settings.

Unveiling the potential of confocal raman spectroscopy in the analysis of oil permeation in human hair fibers

Unveiling the potential of confocal raman spectroscopy in the analysis of oil permeation in human hair fibers

The Time-Varying Characteristics of Relative Permeability in Oil Reservoirs with Gas Injection

Relative permeability is a critical parameter in reservoir numerical simulation and production prediction, intimately associated with reservoir architecture and fluid property. During gas injection development, substantial alterations in reservoir properties and fluid phase behavior induce dynamic changes in relative permeability. Clearly characterizing the time-varying features of relative permeability is very useful for an understanding of how gas injection influences fluid mobility within the reservoir and enhances recovery rates. In this paper, core displacement experiments are firstly conducted to obtain the characteristics of the relative permeability of oil and gas under various development stages and displacement conditions, further delineating the comprehensive shifts in reservoir properties at different gas injection stages. Subsequently, a novel reservoir numerical simulation method is proposed that considers the spatial and temporal segmentation of relative permeability curves in the reservoir simulation. Finally, a practical application is presented to clarify the effects of injection and production parameters on the development performance of gas flooding oil reservoirs. The results show the following: (i) Significant time-varying characteristics of relative permeability occur throughout gas injection development, in the early stages of gas injection, where most of the reservoir is at the gas injection front, and a rightward shift in relative oil and gas permeability indicates that gas injection promotes oil mobility. Conversely, in the later stages of gas injection, as the reservoir reaches the trailing edge of gas injection, the change trend in relative oil and gas permeability reverses, shifting leftward, thereby exacerbating the gas breakout phenomena. (ii) Increasing the rate of gas injection causes relative oil and gas permeability to move leftward, effectively enhancing the gas volume sweep coefficient and microscopic oil displacement efficiency at lower injection speeds while reducing development performance at higher injection speeds. (iii) An increase in gas injection pressure causes relative oil and gas permeability to shift rightward, and although it reduces residual oil saturation and enhances microscopic oil displacement efficiency, it also intensifies gas breakout phenomena and lowers the gas volume sweep coefficient. This paper provides theoretical guidance and technical support for the design of gas injection strategies, optimization of injection and production parameters, and production forecasting.

Shock wave generated by composite energetic material driven by electrical non-penetrating wire explosion plasma.

Underwater shock wave technology can realize dynamic rock fracture, which is helpful to increase oil and gas reservoir permeability. It can realize the efficient exploitation of medium and low maturity oil and gas resources. In practical application, the shock wave parameters require not only high intensity but also safety and controllability. To meet these requirements, insensitive composite energetic materials driven by electrical wire explosion plasma were proposed, which is one of the most promising methods. However, when in use, the load assembly process containing wires and energetic materials is complex. In this paper, a new type of energetic material load is proposed, using non-penetrating wire to drive composite energetic material. It can simplify the production process of the energetic load and produce acceptable shock wave parameters. The test results show that both the energy deposition of the wire and the shock wave intensity decrease under a non-penetrating wire structure. However, the shock wave intensity is still higher than that of the underwater electrical wire explosion. Based on schlieren diagnosis, it is found that the composite energetic material is gradually driven, and the energy release is not concentrated. In addition, the "non-wire" structure driving condition was discussed in contrast. Under this condition, the process of ionization channel establishment in composite energetic materials is random. The shock wave intensity is weak because the composite energetic material is in the process of slow detonation.

Investigation on the oil permeation–adsorption–diffusion combined action mechanism of the adsorbed layer for flexible oil storage in waters

A novel method entitled flexible oil storage in waters is proposed, aiming to address the limitations of current oil storage systems and enhance the country's oil storage capacity. However, oil contamination severely restricts its applicability. To ensure the environmental sustainability of the method, the adsorbed layer is added outside the oil bladder, and the study investigates the material and the action mechanism of the adsorbed layer for flexible oil storage in waters. The results show that, with long breakthrough time and low oil concentration as criteria, the reed straw biochar is more suitable as the adsorbed layer filling material compared to the coconut shell and the apricot shell biochar and the fluorinated ethylene propylene copolymer is more suitable as the adsorbed layer membrane material compared to polyvinyl chloride. The adsorbed layer action mechanism involves multiple interactions, including permeation, adsorption, accumulation, and diffusion. They are coupled and together influence the adsorption effect. The empirical formula for the adsorbed layer's lifespan is derived, which helps in designing the adsorbed layer to satisfy specific lifespan requirements. This study provides theoretical and engineering guidance for the application of flexible oil storage in waters, contributing to the development of oil storage techniques.

Analysis of asynchronous/inter-fracture injection-production mechanism under the condition of five-spot vertical and horizontal well combination in low permeability oil reservoirs

At present, low permeability resources are the focus of the development of petroleum industry. In this paper, firstly, the oil displacement mechanism under the condition of vertical and horizontal well combination is clarified. Secondly, the difference of the mechanism of enhancing oil recovery between asynchronous and inter-fracture injection and production is revealed. Thirdly, the difference of energy supplement mechanism between huff and puff and displacement is compared and analyzed. Results show that: (a) with asynchronous injection-production development, the oil saturation drop around the water injection well is greater than that of periodic injection-production and synchronous injection-production. (b) Under the dual effects of water injection pressure difference and capillary force, part of the injected water enters the reservoir with relatively small pore channels, expanding the swept volume. (c) In the soak stage of asynchronous injection-production development, capillary force is the main control factor of oil-water permeability, and its size determines the permeability level. (d) The injected water first flows through the large channel and then flows into small channel to complete the imbibition and replacement. (e) The flow field of asynchronous injection-production has a large sweep range, which is conducive to improving oil recovery.

Prediction of technological indicators of selective water isolation of water-watered wells by nanostructured gel

In this work the composition forming nanostructured gel, which does not change phase permeability of oil, easily penetrating into water-saturated depth of the formation in watered wells, effectively closing the drainage channels, is established, the possibilities of its rapid heating up to formation temperature, gel formation within a certain time in contact with water depending on the concentration of the selected composition and with its use of involvement in the development of residual oil reserves, which are in watered wells, are investigated at injection of this composition into the well. As an optimal variant of well isolation in terrigenous reservoirs of oil fields it is suggested to use nanocomposite on the basis of silicate gel (with the content of liquid glass 4 % (modulus 3.1), 0.6 % of hydrochloric acid and 0.063 % of metal nanoparticles). The mechanism of selective isolation of water flow in production wells is based on the fact that when the composition is injected into the production well, part of its volume gets into the oil-saturated layer, and the rest – into the water-saturated layer. The composition is distributed in proportion to the permeability of the layers. In the process of well development the composition in the oil-saturated layer is removed, and in the water-saturated layer it retains its isolating properties. The greater the volume of injected fluid, the greater the isolation factor and pressure gradient. The isolation factor is directly proportional to the volume injected. Gel formed in the water-saturated layer corresponding to the volume of the injected composition reduces the phase conductivity on water at least 30 times. Practically does not change the phase conductivity by oil. On the basis of the calculation model including physical and chemical characteristics of selective isolation process taking into account real field conditions, the influence of possibility to isolate bottomhole zone of wells by gel on technological indicators of its operation was estimated. Thus, when putting into operation a well after isolation by water, the production of which was flooded with water, in the initial moments there was a sharp increase in oil flow rate (2–3 times), and at the subsequent stage – a slight decrease in the rate, compared to the flow rate before isolation, the effective time of development or flushing was about 150 days.

Polypyrrole-mediated construction of superhydrophobic photo/electro thermal composite fabric for efficient crude oil dehydration and recovery

During crude oil extraction, transportation, and oil spill recovery, rapid and effective removal of water from crude oil is a great challenge. Super-hydrophobic functional membranes with electrothermal/photothermal effects are considered to be an effective method. However, simply polymerizing photothermal/electrothermal nanomaterials on the membrane surface will lead to unstable thermal effects and easy shedding. Therefore, in this study we propose the synthesis of a novel superhydrophobic electrothermal/photothermal Nylon fabric (PSPPNF) by an innovative in situ polymerization method of Pyrrole (Py), to realize efficient viscosity reduction and dehydration of crude oil. In particular, by controlling FeCl3 solution from solid (−18 °C) to liquid state (0 °C), Py was polymerized on the fabric surface by slow oxidative process, which can effectively solve the problem of pore blocks to obtain a stable-conductive layer on the NF surface. The PSPPNF surface temperature can reach 80 °C under 1 kW m−2 sunlight intensity or by inputting 30 V, which brings a separation efficiency of 97 % for high-viscous crude oil/water mixture. We systematically analyzed the effects of PSPPNF with different pore sizes and oils with different viscosities on the separation flux, as well as the effects of the thermal properties of the membranes under different illumination conditions and voltages on crude oil permeation. Additionally, the PSPPNF combined with the roller can realize all-weather available crude oil spill recovery under solar and electrical energy. This work provides new insights into membrane materials that can realize the efficient dehydration and recovery of crude oil for day-night alternation and complex environments.

Super-hydrophobic ceramic membrane with dense and robust silane grafting for efficient water-in-oil emulsion separation

Separate water from water-in-oil (W/O) emulsions is essential in oil resources recycling and wastewater treatment. Hydrophobic ceramic membranes (HCM) have shown great potential in the dehydration of W/O emulsions but developing high-performance HCM is still a challenge due to the difficulty in hydrophobic modification of ceramic membranes. In this study, an HCM with high grafting density and robust structure was prepared by the grafting silane coupling agent onto an attapulgite (ATP) ceramic membrane. The hexadecyltrimethoxysilane (HDTMS) was chosen for membrane surface modification considering its reaction activity and stability based on molecular dynamic simulation. The effect of the HDTMS contents in the grafting solution and reaction time on the membrane properties were examined. The ATP membrane grafted by HDTMS solution with a content of 9600 ppm for 24 h had a water contact angle of 161° and oil permeability larger than 2207.5 L·m−2·h−1·bar−1 (LMHB). When dealing with W/O emulsions with a water content of 10000 ppm, the steady permeability, permeability recovery ratio, and water rejection of ATP-based HCM was 362 LMHB, 97 %, and 99 %, respectively. Ascribe to the –OH-rich nature of ATP, the performance of HCM in this work is superior to most membranes including Al2O3, ZrO2, and SiC. Hydrophobic-modified ATP provides a new idea for the development of high-performance HCM based on natural mineral ceramics.

Tailoring asymmetric wettability of Janus nanofiber membranes for directional oil transport and oil capture from oil/water mixtures and oil-in-water emulsions

The separation of oil from oil-in-water emulsions is crucial for the recycling of valuable resources. Janus membranes, characterized by their asymmetric configuration, have shown promise in capturing oil from these emulsions due to their ability to efficiently catch micro-size oil droplets with competitive flux rates, minimal energy costs, and fouling-free operations. This study explored the impact of asymmetric wettability on the oil capture capabilities of Janus nanofiber membranes (JNMs). The wettability of the JNMs’ skin layer was modified from oleophilic, with an oil contact angle (OCA) of ∼0°, to oleophobic, with an OCA of ∼142.7°. This adjustment significantly influenced the oil capture process. The oleophobic skin layer acted as a barrier, reducing oil permeation flux from the feed side. However, this same repellent effect facilitated the directional transport of oil once it breached the skin layer. Interestingly, this led to divergent outcomes in the JNMs’ ability to capture oil from oil/water mixture versus oil-in-water emulsion, a distinction not reported in previous studies. These findings are expected to contribute to the enhancement of Janus membranes, optimizing them for more efficient oil recovery from both oil/water mixture and oil-in-water emulsion.

Experimental and numerical studies on CO2 injectivity in low permeability oil reservoirs

Experimental and numerical studies on CO2 injectivity in low permeability oil reservoirs

A novel prediction model of oil-water relative permeability based on fractal theory in porous media

It is significant to accurately evaluate the relative permeability of oil–water two phase for multiphase seepage in porous media in low permeability and tight oil reservoir. However, stress sensitivity is an important characteristic for low permeability and tight oil reservoir. It is an effective way for fractal theory to describe the complexity and heterogeneity of the microstructure of porous media. To describe the relative permeability of oil–water two phase in porous media with complex and irregularity pores, a new relative permeability model oil–water two phases is proposed by the fractal theory and the stress sensitivity is taken into the established model in this paper. Meanwhile, the effects of effective stress, elastic modulus, porosity, maximum and minimum flow radius on oil–water relative permeability are analyzed. The new model is verified by comparing with the laboratory data and the results demonstrate that irreducible water and residual oil saturation have a negative correlation with effective stress. The relative permeability of the oil–water two-phase will shrink to the middle as the rise of effective stress, and the region of co-infiltration will decrease. The deformation quantity of porous media, irreducible water and residual oil saturation will increase as the elastic modulus decreases. The larger the maximum flow radius is, the lower the irreducible water saturation and residual oil saturation is. Both the porosity and the minimum flow radius have slight influences on the relative permeability of oil–water two-phase. The proposed relative permeability model can effectively predict the relative permeability of oil and water and help to describe and reveal the multiphase flow in porous media.