Search Results (27)

Heavy and highly viscous oils account for a significant proportion of the world’s hydrocarbon reserves. The development of these reserves in harsh climates is associated with technological risks due to paraffin deposits and equipment corrosion. Ensuring reliable transportation requires operational monitoring of the physical and chemical properties of fluids directly at the wellhead. Traditional laboratory methods such as SARA fractionation and gas chromatography (GC) are time-consuming and can yield to distortions in the sample composition during transportation. Field optical methods, such as an infrared (IR) spectroscopy are complicated by the optical heterogeneity of crude oils due to emulsified water, supramolecular associations of resins, asphaltenes, and paraffins. In this paper, ultrasonic (US) sample preparation for high-viscosity oils is justified as a method for increasing the reliability and information content of field IR spectroscopic analysis by unmasking the diagnostic extrema of absorption bands that are initially distorted by emulsified water, baseline scattering, and radiation scattering from large resin–asphaltene–paraffin aggregates. The technique is based on cavitation-induced destruction of emulsion shells and disaggregation of the structural framework without volume thermal heating. Experimental data obtained from watered high-viscosity oil has shown that 9 min of the US exposure reduces the light scattering index $I_{\mathrm{t}\mathrm{r}\mathrm{s}}$ by 92.83%, bringing the system into a less heterogeneous state. Statistical correlation analysis confirmed that emulsions and aggregates are the main scattering centers, and their destruction correlates directly with the transparency of the medium. Stability of spectral indices $I_{{\mathrm{C}\mathrm{H}}_3/{\mathrm{C}\mathrm{H}}_2}$, $I_{\mathrm{f}\mathrm{o}\mathrm{c}}$ and $I_{\mathrm{C}=\mathrm{O}}$ indicates the absence of chemical degradation or oxidation at the US exposure intensity of 0.12 W/mL, confirming the physical nature of the effect. The proposed method makes it possible to implement automated monitoring of the properties of high-viscosity oil directly at the wellhead, minimizing logistic costs and risks of the sample degradation. The practical significance of the proposed method is to improve the reliability and information content of wellhead monitoring by reducing optical heterogeneity and making diagnostic significant IR absorption extremes more distinguishable for further interpretation. Full article

High-viscosity reservoirs are widely distributed across various countries with abundant reserves. However, their high resin and asphaltene content leads to elevated oil viscosity and low recovery rates. Conventional chemical flooding techniques are unsuitable for the development of such high-viscosity oilfields. Chemical viscosity reduction technologies face challenges such as low viscosity reduction efficiency, poor economic feasibility, and unclear mechanisms. Microbial-assisted chemical viscosity reduction represents a relatively novel approach. This study systematically investigated the enhanced oil recovery performance of a microbial-assisted chemical viscosity reducer. The results demonstrated that this microbial-assisted chemical viscosity reducer achieved a viscosity reduction rate exceeding 85% for five different crude oil samples. It effectively altered the wettability of oil-wet surfaces, improved the oil film stripping rate by 50–65% compared to pure chemical flooding agents, and achieved ultra-low oil–water interfacial tension on the order of 10⁻³ mN/m with crude oil, leading to an enhanced oil recovery (EOR) enhancement of 22–26%. The underlying mechanism is that viscosity-reducing bacteria degrade asphaltene in heavy oil, thereby weakening intermolecular forces. Their metabolites enhance the emulsion stability of the chemical viscosity reduction process. Chemical viscosity reducers enhance the physiological cycle and metabolic activity of microorganisms while also emulsifying and dispersing heavy oil and improving emulsion stability. Therefore, this novel microbial-assisted chemical viscosity reduction technology offers a new and effective EOR method for high-viscosity reservoirs. Full article

Shale oil is abundant in geological reserves, but its recovery rate is low due to its unique characteristics of ultra-low porosity, ultra-low permeability, and high clay content. This study investigated the effect of mixed-charge surfactants (PSG) on enhanced oil recovery (EOR) in high-temperature shale reservoirs, building on our previous research. The results indicate that PSG not only has outstanding interfacial activity, anti-adsorption, and high-temperature resistance but can also alter the wettability of shale. After aging at 150 °C for one month, a 0.2% PSG solution exhibited minimal influence on the viscosity reduction and oil-washing properties but significantly altered the oil/water interfacial tension (IFT). Compared to field water, the 0.2% PSG solution enhances the static oil-washing efficiency by over 25.85% at 80 °C. Moreover, its imbibition recovery rate stands at 29.03%, in contrast to the mere 9.84% of field water. Because of the small adhesion work factor of the PSG solution system, it has a strong ability to improve shale wettability and reduce oil/water IFT, thereby improving shale oil recovery. This study provides the results of a laboratory experiment evaluation for enhancing shale oil recovery with surfactants. Furthermore, it holds significant potential for application in the single-well surfactant huff-n-puff process within shale reservoirs. Full article

The development of nanofluid-assisted heavy oil extraction can address critical challenges in global energy sustainability, particularly for ultra-heavy oil reserves characterized by high viscosity and low permeability. This study investigates the dual role of hydrophobic nanofluids in enhancing reservoir permeability and heat transfer efficiency. Through advanced triaxial shear seepage experiments and heat transfer experiments, the permeability and thermal conductivity of oil sands cores treated with hydrophobic silica-based nanofluids (0–0.15 wt%) were quantitatively analyzed. The results showed that the permeability increased by up to 536.59% (from 33.18 mD to 211.22 mD) after nanofluid treatment, which was attributed to nanoparticle-induced pore throat modification and reduced interfacial tension. At the same time, the thermal conductivity has increased by up to 132% (from 0.25 W/m·K to 0.58 W/m·K), significantly improving the heat transfer efficiency. There is a linear relationship between the concentration of nanofluids and the thermal conductivity, and the relationship between the thermal conductivity, and the strain of oil sands is established. This work provides a scientifically grounded framework for scaling nanofluid applications in field trials, offering a transformative pathway to reduce energy intensity and improve recovery rates in ultra-heavy oil exploitation. Full article

The escalating energy demand has prompted nations to prioritize the development of high-viscosity and challenging-to-extract heavy and extra-heavy oil reserves. Consequently, the technique of in-situ combustion in oil reservoirs by injecting air to ignite heavy oil resources, leveraging the generated heat to enhance recovery rates, is a particularly critical extraction method. However, simulation studies of in-situ combustion techniques are still primarily conducted at a macroscopic level. Therefore, conducting more detailed numerical simulation studies holds significant importance. This paper establishes a mathematical model for heat transfer within reservoirs during in-situ combustion, thoroughly investigating the effects of inlet temperature, injection pressure, injection duration, and porosity on the heat transfer processes inside the reservoir. The research demonstrates that the reservoir’s internal temperature gradually rises as the injection duration increases. Additionally, porosity (an increase from 0.1 to 0.3 enhances the heat propagation rate by 15%) and injection pressure (an increase from 5 MPa to 8 MPa boosts the heat propagation rate by 25%) significantly affect the heat transfer rate. Full article

The depletion of petroleum reserves and increasing environmental concerns have driven the development of eco-friendly asphalt binders. This research investigates the performance of natural asphalt (NA) modified with waste engine oil (WEO) as a sustainable alternative to conventional petroleum asphalt (PA). The study examines NA modified with 10%, 20%, and 30% WEO by the weight of asphalt to identify an optimal blend ratio that enhances the binder’s flexibility and workability while maintaining high-temperature stability. Comprehensive testing was conducted, including penetration, softening point, viscosity, ductility, multiple stress creep recovery (MSCR), linear amplitude sweep (LAS), energy-dispersive X-ray spectroscopy (EDX), Fourier transform infrared (FTIR) spectroscopy, and scanning electron microscopy (SEM). The results reveal that WEO effectively softens NA, improves ductility, and enhances workability, with the 20% WEO blend achieving the best balance of physical and rheological properties. Chemical analysis indicates that WEO increases carbon content and reduces sulfur and impurities, aligning NA’s composition closer to PA. However, excessive WEO (30%) compromises thermal stability and deformation resistance. The findings underscore the potential of WEO-modified NA for sustainable pavement applications, with 20% WEO identified as the optimal content to achieve performance comparable to conventional petroleum asphalt while promoting environmental sustainability. Full article

Heavy crude oil (HCO) and extra-heavy crude oil (EHCO) with high viscosity and density pose enormous challenges to the exploitation of oil reserves. While bacteria are increasingly used in biocatalytic upgrading of HCO and EHCO, less attention has been paid to the potential of fungi. The aim of this study was to ascertain the role of fungal extracellular enzymes from Aspergillus spp. In the biodegradation of EHCO and their application potential for enhanced oil recovery. A. terreus HJ2 and A. nidulans HJ4 with the ability to biodegrade HCO were previously isolated from bitumen enrichment cultures. Both strains grew well on EHCO agar plates supplemented with a small amount of soluble starch (0.2%) and yeast extract (0.3%). Extracellular enzymes from each strain separately, as well as mixtures of the enzymes, exhibited EHCO degradation activity, leading to redistribution of hydrocarbons with substantial formation of biogases and organic acids in a 7-day period. Enzymatic degradation resulted in decreased contents of resins and asphaltenes, accompanied by increased contents of saturates and aromatics. Gas chromatography–mass spectrometry revealed distinct redistribution patterns of n-alkane in the biotreated oil. Enzymatic degradation additionally caused considerable reduction in oil viscosity (by 12.7%) and heavy metal concentrations (Ni, by 44.1%; Fe, by 54.0%; V, by 31.6%). The results provide empirical evidence for the application potential of fungal extracellular enzymes from Aspergillus spp. in EHCO recovery and biocatalytic upgrading of EHCO. Full article

China boasts significant reserves of low-permeability oil reservoirs, and the economic and efficient development of these reservoirs plays a crucial role in enhancing oil and gas production. However, the “difficult injection and difficult recovery” issue in low-permeability oil reservoirs is a major challenge. To address this, research is conducted on the mechanism of pressure drive based on the mathematical model of oil-water seepage in low-permeability reservoirs and the model of fracture permeability. The study finds that pressure drive technology, by directly delivering the pressure drive agent deep into the low-permeability reservoir, effectively prevents viscosity loss and adhesion retention of the agent in the near-wellbore area. This technology expands the swept volume, improves oil washing efficiency, replenishes formation energy, and facilitates the gathering and production of scattered remaining oil. For reservoirs with higher permeability, pressure drive yields quick results, and high-pressure water injection can be directly adopted for pressure drive to reduce costs. On the other hand, reservoirs with lower permeability have difficulty in water absorption, and the use of surfactant-based pressure drive can effectively reduce the seepage resistance of the reservoir, enhancing its water absorption capacity and improving development outcomes. Based on the mechanism of pressure drive development, further research is conducted on the production characteristics of pressure drive mines. Addressing the variability in pressure drive effects, big data analysis tools such as SHAP analysis and correlation analysis are employed to evaluate the main controlling factors of pressure drive in both new and old areas. Additionally, non-time series and time series pressure drive production forecasting models are established based on pressure drive data. Full article

The depletion of conventional light petroleum reserves has intensified the search for alternative sources, notably, low-quality heavy oils and byproducts from heavy crude processing, to meet the global demand for fuels, energy, and petrochemicals. Heavy crude oil (HO) and extra heavy crude oil (EHO) represent nearly 70% of the world’s reserves but require extensive upgrading to satisfy refining and petrochemical specifications. Their high asphaltene content results in elevated viscosity and reduced API gravity, posing significant challenges in extraction, transportation, and refining. Advanced catalytic approaches are crucial for efficient asphaltene removal and the conversion of heavy feedstocks into valuable light fractions. Kaolin, an aluminosilicate mineral, has emerged as a key precursor for zeolite synthesis and a promising catalyst in upgrading processes. This article provides a comprehensive exploration of kaolin’s geological origins, chemical properties, and structural characteristics, as well as the various modification techniques designed to improve its catalytic performance. Special focus is given to its application in the transformation of heavy crudes, particularly in facilitating asphaltene breakdown and enhancing light distillate yields. Finally, future research avenues and potential developments in kaolin-based catalysis are discussed, emphasizing its vital role in addressing the technological challenges linked to the growing reliance on heavier crude resources. Full article

Immense use of fossil fuels leads to various environmental issues, including greenhouse gas emissions, reduced oil reserves, increased energy costs, global climate changes, etc. These challenges can be tackled by using alternative renewable fuels such as biodiesel. Many studies reported that biodiesel production from microalgae biomass is an environment-friendly and energy-efficient approach, with significantly improved fuel quality in terms of density, calorific value and viscosity. Biodiesel is produced using the transesterification process and the most sustainable method is utilizing enzymes for transesterification. Lipase is an enzyme with excellent catalytic activity, specificity, enantio-selectivity, compatibility and stability and hence it is applied in microalgae biodiesel production. But, difficulty in enzymatic recovery, high enzyme cost and minimal reaction rate are some of its drawbacks that have to be addressed. In this aspect, the nanotechnological approach of lipase immobilization in producing microalgae biodiesel is a promising way to increase production yield and it is due to the adsorption efficiency, economic benefit, recyclability, crystallinity, durability, stability, environmental friendliness and catalytic performance of the bio-nanoparticles used. Through increasing post-harvest biomass yield, absorption of CO₂ and photosynthesis in the photobioreactor, the use of nanoparticle immobilized lipase during the generation of biodiesel from microalgae has the potential to also remove feedstock availability constraints. This review article discusses the production of microalgae biodiesel, and effect of nanoparticles and immobilized lipase nanoparticles on biodiesel production. The advantages of using lipase nanoparticles and the challenges in introducing the immobilized lipase on nanoparticles in large-scale microalgae biodiesel production are also discussed. Reducing the water and land use, energy and nutrient footprints of integrated algae-based operations must be the main goal of larger-scale experiments as well as ongoing research and development in order to expedite the adoption of microalgae-based biodiesel production. Also, the cost-effectiveness and large-scale availability of nanoparticles and the impact of lipase nanoparticles on engine performance should be analyzed for commercialization of microalgae biodiesel. Full article

Oil and gas reservoirs in volcanic rocks are a particular type of unconventional reservoir and present unique challenges for exploration and production engineers. To help the oil industry understand volcanic reservoirs and solutions to complex development problems, we reviewed their key engineering technologies as well as their geological characteristics. The distinctive geological characteristics of volcanic hydrocarbon reservoirs are strong heterogeneity, low porosity and permeability, complex fracture systems, etc. The volcanic reservoir rock types in order of hydrocarbon abundance are basalt (38.5%), andesite (15.9%), volcaniclastic (12.1%), and rhyolite (11.5%). The porosity ranges from 0.1 to 70%, and permeability ranges from 0.0007 to 762 md. In some commercially developed volcanic reservoirs of China, the average porosity is 7.7–13%; the average permeability is 0.41–3.4 md. Engineers have applied a variety of adapted technologies to produce volcanic reservoir economically. Horizontal wells can increase production and reserves by 4–6 times those of vertical wells, and longer wells are preferred. Specialized hydraulic fracturing techniques are suggested, including small or mixed proppant size, second HF treatment after proppant slugging, high-viscosity frac fluid with high-temperature resistance, special fluid loss reducer, high pump pressure, Extreme Overbalance Perforating, limited-entry fracturing, matrix acidizing, etc. Water control measures include producing below critical rates, partial perforation or penetration, controlling hydraulic fracture height, using horizontal wells, implementing complete cementing job, etc. Well productivity evaluation should be conducted to understand well performance and appropriately allocate production rates among wells, using the modified AOF method and other productivity prediction models considering breakdown fracture gradient, gas slippage effect, non-Darcy effect, etc. Well sites need to be selected based on recognizing profitable lithologies, lithofacies, high porosity and permeability, relatively developed fracture systems, thick net pay zones, etc. The critical questions for the industry are how to enhance volcanic reservoir recovery with more efficient and economic hydraulic fracturing and water control techniques. This is one of the first papers systematically summarizing the engineering technologies and unique solutions to develop volcanic reservoirs. Further and more complete reviews can be carried out in the future, and more novel and effective techniques can be explored and tested in the field. Full article

The growing energy demand has created a special interest in the unconventional reserves of heavy and extra-heavy oil, despite their difficulty both in extraction and separation due to the high specific gravity, high viscosity, low mobility, and high content in asphaltenes and heteroatoms. The study is a comprehensive review of the implemented technologies and emerging techniques for the dehydration of heavy and extra-heavy oils with an °API gravity from 20 to below of 10 and a viscosity between 100 and 10,000 cP. Special focus is given to the electrostatic treatment, due to its versatility of applications and its potential for the further improvement in dehydration efficiency, thus reducing the demand for energy and chemical demulsifiers. Full article

This article analyzes the dependence of the choice of the method of transportation of high-viscosity oil on the rheological characteristics of the oil in question. An analysis of existing rheological models of high-viscosity oil was carried out, and it was found that a number of models have certain features (model coefficients, their purpose, quantity) that affect the choice of a rheological model of oil. The dependences for determining the coefficient of dynamic viscosity when pumping high-viscosity oil with the addition of pour-point depressants were studied, and the dependence of the hydraulic resistance coefficient when depressants are added to the oil was obtained. A method for choosing a rational oil heating temperature and diluent concentration to achieve the maximum pipeline performance is substantiated. Full article

Currently, most explored oil fields in Russia are at a late stage of development, and in order to maintain high levels of oil production, it is rational to put into operation fields with hard-to-recover reserves. For complicated oil fields, in particular fields with high-viscosity oil, the known traditional methods of development are ineffective. Therefore, the search for new technologies for the development and operation of such fields to significantly increase oil recovery and intensify production is of fundamental importance. One such method of heat treatment of the bottomhole formation zone is the use of heat and gas generating systems on site. In this work, new results were obtained on physical modeling of thermochemical reaction initiation with delayed-action catalyst (2,2-bis(hydroxymethyl)butanoic acid) filtration tests on composite core models of sandstone and carbonate with foam heat generation and initiating additives of binary type. Using hydrodynamic modelling, the results of laboratory studies were reproduced, and the preliminary efficiency of the developed technology for thermochemical treatment of deposits in the Samara region (Russia) was evaluated. Full article

Heavy oil reservoirs are often characterized by high viscosity and poor mobility, which is more complex with the presence of bottom water. The conventional vertical well development method has low oil recovery efficiency and limited controlled reserves of a single well. In addition, water cut can increase dramatically when the edge-bottom water breaks through. Horizontal well and CO₂ huff-n-puff is an effective alternative development model for heavy oil reservoirs. This development method makes efficient use of CO₂ and accords with the “Carbon Capture, Utilization, and Storage (CCUS)”. The horizontal well can increase the drainage area. The dissolution of CO₂ improves the mobility of crude oil and increases formation energy. In this paper, we established numerical simulation models based on the Liuguanzhuang oilfield in Dagang. The characteristics and producing rules of the horizontal well and CO₂ huff-n-puff development in the heavy oil reservoir were studied. The results show that the production characteristics of horizontal well and CO₂ huff-n-puff were similar to Steam-Assisted Gravity Drainage (SAGD). CO₂ forms a viscosity reduction area above the horizontal well and the heavy oil flows into the wellbore due to gravity after viscosity reduction. The CO₂ huff-n-puff can effectively enhance the production area of horizontal wells compared with the depletion development. However, the improvement in the production area gradually decreased as CO₂ huff-n-puff cycles continued. There was a boundary of production area against the horizontal well, with the main production of heavy oil occurring at the upper and either end of the horizontal well. The CO₂ huff-n-puff has a restraining effect on the edge-bottom water, which is confirmed via the proposed theoretical model. Full article