Light Oil Research Articles

Enrichment factors of movable hydrocarbons in lacustrine shale oil and exploration potential of shale oil in Gulong Sag, Songliao Basin, NE China

The geological characteristics and production practices of the major middle- and high-maturity shale oil exploration areas in China are analyzed. Combined with laboratory results, it is clear that three essential conditions, i.e. economic initial production, commercial cumulative oil production of single well, and large-scale recoverable reserves confirmed by the testing production, determine whether the continental shale oil can be put into large-scale commercial development. The quantity and quality of movable hydrocarbons are confirmed to be crucial to economic development of shale oil, and focuses in evaluation of shale oil enrichment area/interval. The evaluation indexes of movable hydrocarbon enrichment include: (1) the material basis for forming retained hydrocarbon, including TOC>2% (preferentially 3%–4%), and type I–II1 kerogens; (2) the mobility of retained hydrocarbon, which is closely related to the hydrocarbon composition and flow behaviors of light/heavy components, and can be evaluated from the perspectives of thermal maturity (Ro), gas-oil ratio (GOR), crude oil density, quality of hydrocarbon components, preservation conditions; and (3) the reservoir characteristics associated with the engineering reconstruction, including the main pore throat distribution zone, reservoir physical properties (including fractures), lamellation feature and diagenetic stage, etc. Accordingly, 13 evaluation indexes in three categories and their reference values are established. The evaluation indicates that the light shale oil zones in the Gulong Sag of Songliao Basin have the most favorable enrichment conditions of movable hydrocarbons, followed by light oil and black oil zones, containing 20.8×108 t light oil resources in reservoirs with Ro>1.2%, pressure coefficient greater than 1.4, effective porosity greater than 6%, crude oil density less than 0.82 g/cm3, and GOR>100 m3/m3. The shale oil in the Gulong Sag can be explored and developed separately by the categories (resource sweet spot, engineering sweet spot, and tight oil sweet spot) depending on shale oil flowability. The Gulong Sag is the most promising area to achieve large-scale breakthrough and production of continental shale oil in China.

Numerical and artificial neural network analysis of an axisymmetric co-flow-focusing microfluidic droplet generator using active and passive control

Droplet generation in microscale has gained enormous attention in recent years especially in the pharmaceutical industry due to their application in targeted drug delivery into droplets. In most of these applications, monodispersity and uniformity of droplets are essential. Microfluidic devices can generate droplets at high throughput, enabling thousands of droplet compound encapsulation per second. The monodispersity of the droplets is ensured hydrodynamically through the dripping regime and their uniformity is controlled by active and passive microflow control methods. Here, we study numerically a microfluidic chip that uses a non-embedded co-flow-focusing geometry, so that the droplet generation throughput can take advantage of the flow-focusing devices while the non-embedded co-flow geometry forecloses the surfactant addition necessity. The continuous and dispersed phases were light mineral oil and water, respectively. We investigated the formation of droplets and studied how changing the external diameter of the chip affects the transition between the dripping regime (which corresponds to monodispersity) and the jetting regime. The number of parameters to be taken into account for the optimization of the device is enormous; therefore, in order to account for the effect of many geometrical and hydrodynamical parameters, we trained an artificial neural network based on our simulation data. Using this neural network, we evaluated droplet formation in 3240 different cases. This approach resulted in a remarkable reduction of computation time, from months to seconds. Examining numerous cases in such a short period lets us choose the optimum geometry and flow rate based on the application. The optimization was able to find the best geometry to extend the region of dripping regime in the flow rate map. Finally, to harness the droplet generation frequency, we also simulated a periodically switched laser and we were able to predict the generation of droplets with the same frequency as the switching frequency. Therefore, altering and controlling the frequency and dimensions of the droplets for a given flow rate ratio could be achieved with this technique, even without satellite droplets.

Shale oil enrichment evaluation and production law in Gulong Sag, Songliao Basin, NE China

Based on the results of drilling, tests and simulation experiments, the shales of the Cretaceous Qingshankou Formation in the Gulong Sag of the Songliao Basin are discussed with respect to hydrocarbon generation evolution, shale oil occurrence, and pore/fracture evolution mechanism. In conjunction with a substantial amount of oil testing and production data, the Gulong shale oil enrichment layers are evaluated and the production behaviors and decline law are analyzed. The results are drawn in four aspects. First, the Gulong shales are in the stage of extensive hydrocarbon expulsion when Ro is 1.0%–1.2%, with the peak hydrocarbon expulsion efficiency of 49.5% approximately. In the low–medium maturity stage, shale oil migrates from kerogen to rocks and organic pores/fractures. In the medium–high maturity stage, shale oil transforms from adsorbed state to free state. Second, the clay mineral intergranular pores/fractures, dissolution pores, and organic pores make up the majority of the pore structure. During the transformation, clay minerals undergo significant intergranular pore/fracture development between the minerals such as illite and illite/smectite mixed layer. A network of pores/fractures is formed by organic matter cracking. Third, free hydrocarbon content, effective porosity, total porosity, and brittle mineral content are the core indicators for the evaluation of shale oil enrichment layers. Class-I layers are defined as free hydrocarbon content equal or greater than 6.0 mg/g, effective porosity equal or greater than 3.5%, total porosity equal or greater than 8.0%, and brittle mineral content equal or greater than 50%. It is believed that the favourable oil layers are Q2–Q3 and Q8–Q9. Fourth, the horizontal wells in the core area of the light oil zone exhibit a high cumulative production in the first year, and present a hyperbolic production decline pattern, with the decline index of 0.85–0.95, the first-year decline rate of 14.5%–26.5%, and the single-well estimated ultimate recovery (EUR) greater than 2.0×104 t. In practical exploration and production, more efforts will be devoted to the clarification of hydrocarbon generation and expulsion mechanisms, accurate testing of porosity and hydrocarbon content/phase of shale under formation conditions, precise delineation of the boundary of enrichment area, relationship between mechanical properties and stimulated reservoir volume, and enhanced oil recovery, in order to improve the EUR and achieve a large-scale, efficient development of shale oil.

NMR-Based Analysis of Fluid Occurrence Space and Imbibition Oil Recovery in Gulong Shale

The Gulong shale oil reservoir is situated in freshwater to slightly saline lacustrine basins mainly consisting of a pure shale geological structure, which is quite different from other shale reservoirs around the world. Currently, the development of Gulong shale oil mainly relies on hydraulic fracturing, while the subsequent shut-in period for imbibition has been proven to be an effective method for enhancing shale oil recovery. To clarify the characteristics of the fluid occurrence space and the variation in the fluid occurrence during saltwater imbibition in Gulong shale, this paper carried out porosity and permeability tests on Gulong shale cores and analyzed the fluid occurrence space characteristics and imbibition oil recovery based on nuclear magnetic resonance (NMR). In the porosity and permeability tests, T2 distributions were used to correct the porosity measured by the saturation method to obtain the NMR porosity. Combined with the identification of fractures in shale cores using micro-CT and the analysis of porosity and permeability parameters, it was found that the permeability of the shale cores was related to the development of fractures in the shale cores. Through the testing and analysis of T1-T2 maps of the shale cores before and after saturation with oil, it was found that the shale mainly contained heavy oil, light oil, and clay-bound water, and they were distributed in different regions in the T1-T2 maps. Finally, the T1-T2 maps of the shale cores at different imbibition stages were analyzed, and it was found that saltwater mainly entered the minuscule inorganic pores of clay minerals during the imbibition process and squeezed the larger-sized inorganic pores containing light oil through the hydration expansion effect, thus expelling the light oil from the shale core and achieving the purpose of enhanced oil recovery.

Trimethylolpropane based biolubricant synthesis from sweet almond (Prunusamygdalus dulcis) seed oil for use in automotive applications.

This paper presents a synthesis of a sweet almond oil-based trimethylolpropane biolubricant and the evaluation of its temperature-dependent viscosity properties. The oil was converted into biodiesel by the transesterification process after extraction, refining, and acid-alkaline transesterification. After that, biolubricant was produced by further transesterifying biodiesel with trimethylolpropane at 105 oC at a ratio of 3.9:1 for a 60-minute reaction time with a potassium hydroxide catalyst concentration of 1 wt. %. According to the American Standard Test Methods (ASTM), the biolubricant's pour point and index of viscosity were determined to be 267.50 and -4 oC, respectively. The measured viscosities were 42.80, 30.18, 21.39, 12.25, and 8.90 cSt. cSt at 30, 40, 60, 80, and 100 °C, demonstrating an inverse relationship between temperature and lubricant viscosity. The difference between the FTIR spectra of the biodiesel and the biolubricant—1755.74 cm-1 versus 1743.96 cm-1—verifies the ester group. Sweet almond oil has a higher iodine content than unsaturated glycerides (9.52 g of iodine per 100 g of oil sample) and includes 53.478 % more unsaturated fatty acids than saturated fatty acids, and 71.725 % unsaturated fatty acids for biolubricant according to gas chromatographic data. Linoleic acid made up the majority of the fatty acids in the oil and synthetic biolubricant, with percentages of 31.44 and 45.93 %, respectively. Sweet almond biolubricant and oil contained palmitic, linoleic, and oleic acids. The biolubricant has the potential to function as light gear oil for automobiles because its characterization results correlate favorably with the ISO VG-32 criteria

Accelerated optimization of CO2-miscible water-alternating-gas injection in carbonate reservoirs using production data-based parameterization

Enhancing oil recovery in reservoirs with light oil and high gas content relies on optimizing the miscible water alternating gas (WAG) injection profile. However, this can be costly and time-consuming due to computationally demanding compositional simulation models and numerous other well control variables. This study introduces WAGeq, a novel approach that expedites the convergence of the optimization algorithm for miscible water alternating gas (WAG) injection in carbonate reservoirs. The WAGeq leverages production data to create flexible solutions that maximize the net present value (NPV) of the field, while providing practical implementation of individual WAG profiles for each injector. The WAGeq utilizes an injection priority index to rank the wells and determine which should inject water or gas at each time interval. The index is built using a parametric equation that considers factors such as producer and injector relationship, water cut (WCUT), gas–oil ratio (GOR), and wells cumulative gas production, to induce desirable effects on production and WAG profile. To evaluate WAGeq’s effectiveness, two other approaches were compared: a benchmark solution named WAGbm, in which the injected fluid is optimized for each well over time, and a traditional baseline strategy with fixed 6-month WAG cycles. The procedures were applied to a synthetic simulation case (SEC1_2022) with characteristics of a Brazilian pre-salt carbonate field with karstic formations and high CO2 content. The WAGeq outperformed the baseline procedure, improving the NPV by 6.7% or 511 USD million. Moreover, WAGeq required fewer simulations (less than 350) than WAGbm (up to 2000), while delivering a slightly higher NPV. The terms of the equation were also found to be essential for producing a WAG profile with regular patterns on each injector, resulting in a more practical solution. In conclusion, WAGeq significantly reduces computational requirements while creating consistent patterns across injectors, which are crucial factors to consider when planning a practical WAG strategy.

Recent Advances in the Study of In Situ Combustion for Enhanced Oil Recovery

Global estimates for our remaining capacity to exploit developed oil fields indicate that the currently recoverable oil (light oil) will last for approximately 50 years. This necessitates the development of viscous and superviscous oil fields, which will further compensate for the loss of easily produced oil. In situ combustion is the most promising production method, which allows for increased oil recovery from a reservoir. This being the case, this study provides an overview of global trends regarding the research and implementation of the method under consideration, in order to promote understanding of its applicability and effectiveness. The background to the development of the method is discussed in detail, illustrating the growing interest of researchers in its study. Cases of both successful as well as inefficient implementations of this method in real oil fields are considered. The main focus of the article is to investigate the influence of the parent rock and catalysts on the combustion process, as this is a new and actively developing area in the study of enhanced oil recovery using in situ combustion. Geological surveys, in addition to experimental and numerical studies, are considered to be the main methods that are used to investigate processes during in situ combustion. The analysis that we carried out led us to understand that the processes which occur during the combustion of heavy oil are practically unpredictable and, therefore, poorly understood. The specificity of the oil composition under consideration depends on the field, which can lead to a change in the required temperature regimes for its production. This indicates that there exists multiple specific applications for the method under consideration, each requiring additional full studies into both the fractional composition of oil and its reservoirs. The article also considers various technologies for implementing the in situ combustion method, such as ND-ISC, THAITM, COSH, CAGD, and SAGD. However, the literature review has shown that none of the technologies presented is widely used, due to the lack of an evidence base for their successful application in the field. Moreover, it should be noted that this method has no limits associated with the oil occurrence depth. This technology can be implemented in thin reservoirs, as well as in flooded, clayey, sandy, and carbonate reservoirs. The review we have presented can be considered as a guide for further research into the development of global solutions for using the proposed method.

FORMATION OF BUSHINESS OF SPRING TRITICALE VARIETIES DEPENDING ON THE PREDECESSOR AND FERTILIZER

The article highlights the influence of precursors and levels of mineral fertilization on the formation of productive bushiness of spring triticale of different varieties. Depending on the influence of meteorological factors and weather, the influence of the studied elements of winter triticale cultivation technology, the indicators of the level of bushiness changed. The highest productive bushiness was formed by plants in the variants in which the best conditions were created for this. Triticale is an artificially bred crop that has not been studied enough in the global economy and requires research, but in Ukraine it is a well-known crop that takes its share in the overall crop structure. For example, the use of different norms of nitrogen fertilizers on the background of P60К60 contributed to an increase in the number of productive stems per unit area, and, accordingly, in the productive bushiness in general. When applying phosphorus and potassium fertilizers (P60К60), the number of productive stems did not exceed 585-591 pcs./m2, and the productive bushiness was 1.58-1.59, respectively. Triticale consumes a lot of nutrients from the soil to form a crop, which requires additional fertilization. It is not customary to apply organic fertilizers to this crop. only under its predecessors. Depending on the soil fertility, 60 to 90 kg of nitrogen, phosphorus and potassium are applied. Phosphorus and potash fertilizers are scattered under the main cultivation. And nitrogen fertilizers are divided into three fertilizing sessions during the phases of active plant growth. Experts also advise to apply superphosphate 10-15 kilograms per hectare during sowing with seeds. Triticale is very sensitive to sowing dates, which roughly coincide with the middle of the optimal sowing period for winter wheat. For sowing, it is necessary to select seeds with a germination rate of at least 92% and a purity of at least 98%. Treatment with compositions designed for winter wheat has a good effect on the yield. In most farms, the crop is sown using intensive technology in a row with the skipping of technological paths. Some farms use a cross-row or narrow-row sowing method. The seeding rate is usually between 1.5 and 5.5 million germinating grains per hectare. The recommended sowing depth is 4-6 cm, reduced on heavy soils and increased by 1-2 cm on light soils. By selecting the best predecessors, namely soybeans, sunflower and corn, we created optimal conditions for the productivity of this crop. In addition, mineral fertilizers had a positive effect on the formation of bushiness of spring triticale.

Application of artificial neural network for prediction of 10 crude oil properties

AbstractThis study aims to develop an industrially reliable and accurate method to estimate crude oil properties from their Fourier transform infrared spectroscopy (FTIR) spectra. We used the complete FTIR spectral data of selected crude oil samples from seven different Canadian oil fields to predict 10 important crude oil properties using artificial neural networks (ANNs). The predicted properties include specific gravity, kinematic viscosity, total acid number, micro carbon content, and production of light and heavy naphtha, Kero, and distillate in oil refineries. The 107 different (65 light oil and 42 heavy/medium oil samples) crude oil samples used in this study came from seven oil fields and reservoirs across Canada. In line with standard practice, we used 80% of the dataset for training the ANN models and used the remaining 20% of the crude oil samples to test the models. In the ANN analysis, the mean squared error (MSE) was used as the loss function in models, and the mean absolute prediction error (MAPE) was used as a reference to compare the performance of different neural networks constructed with different numbers of layers. This work demonstrates that FTIR spectroscopy is a promising technique that provides rapid and accurate estimates for the oil properties of interest to the industry. A comparison of the values predicted by the validated ANN models and their corresponding measured (actual) values showed excellent prediction with the acceptable range of error (below 15%) aimed for by our industry partner for all properties except viscosity, for which building models based on the natural logarithmic values of measured viscosities significantly improved the results.

Fundamentals of crystallization at oil-brine interfaces for conformance control and oil spill remediation applications

We have investigated the interfacial properties at a brine-hydrocarbon boundary with the prospect of understanding the crystallization process that takes place when certain electrolytes are present in the brine and when certain surfactants are present in the hydrocarbon phase. Solutions of nine cations and five carboxylic acids were investigated. We found that some combinations of electrolytes and acids than others are solidified at the brine-hydrocarbon interface. These interfacial phenomena were studied with an optical force tensiometer setup with a so-called buoyant droplet configuration. aim to utilize these specific interfacial formed crystals to design a method to form crystal plugs in high-flow sections (e.g., at fractures) of an oil reservoir. Ultimately, our studies target a real reservoir environment and we have included a range of different crudes with varying total acid numbers (TAN) and viscosities to bring the study a little closer to a realistic upstream setting. The electrolyte-surfactant combination that gives rise to the most clear-cut formation of crystals directly at the interface is involving Zn2+ or Cu2+ and dodecanoic acid (C11H23COOH). Several of the systems under study appears to be forming crystals within the hydrocarbon phase; these crystals are more likely a result of the surfactant-associated diffusive transfer of cations into the hydrocarbon phase with subsequent complexation. When it comes to the crudes, the findings are somewhat more complex, the acidity of the oil, not surprisingly, influences the interfacial properties including the crystallization propensity. The relationship between one-dimensional parameters such as TAN and crystallization propensity is not straightforwardly interpreted but it does seem like proper spiking can induce crystallization in most oils and that it is most favorably done in light oils where the diffusivity of the acids is largest. We have made the applicational space wider by also showing that the crystallization/interfacial phenomena can induce confinement of oil on a water surface; an observation that opens applications in oil spill remedies.

Hybrid electrodes effective for both electrowetting‐ and dielectrowetting‐driven digital microfluidics

AbstractElectrowetting on dielectric (EWOD) and dielectrowetting (DEW) are two major principles to drive droplets in digital microfluidics. EWOD is effective to manipulate (create, transport, split, and merge) conductive droplets being currently used for many biological, chemical, and optical applications. DEW can also manipulate droplets but more efficiently with dielectric (nonconductive) fluids. A digital microfluidic platform efficiently operable by both EWOD and DEW would offer higher versatility in handling a wide range of fluids, regardless of their conductivities. In this regard, this article presents a new hybrid electrode design enabling EWOD and DEW to drive various kinds of droplet fluids on a single platform. In addition, a slippery liquid‐infused surface (SLIPS) is integrated with the hybrid electrodes. The SLIPS is well known to resist biofouling and repel sticky fluids, which endows the hybrid electrodes with much wider application spectra. As a result, the present SLIPS‐integrated hybrid electrodes facilitate actuating various kinds of fluids which would not be driven by conventional EWOD and/or DEW electrodes. This paper presents the successful transportation of not only conductive fluids including water, protein solution, glycerol, and honey but also nonconductive fluids including dodecane, silicone oil, and light and heavy crude oil, all driven by the SLIPS‐integrated hybrid electrodes. The performance comparisons among solid, interdigitating, and hybrid electrodes are made by testing both conductive and nonconductive droplets.

Dry heating affects the multi-structures, physicochemical properties, and in vitro digestibility of blue highland barley starch.

As a physical method for starch modification, dry heating treatment (DHT) at high temperatures (150 and 180°C, respectively) was applied to blue highland barley (BH) starch with different durations (2 and 4 h). The effects on its multi-structures, physicochemical properties, and in vitro digestibility were investigated. The results showed that DHT had changed the morphology of BH starch, and the diffraction pattern remained an "A"-type crystalline structure. However, with an extension of DHT temperature and time, the amylose content, gelatinization temperature, enthalpy value, swelling power, and pasting viscosity of modified starches decreased, while the light transmittance, solubility, and water and oil absorption capacities increased. Additionally, compared with native starch, the content of rapidly digestible starch in modified samples increased after DHT, whereas those of slowly digestible starch and RS decreased. Based on these results, the conclusion could be drawn that DHT is an effective and green way to transform multi-structures, physicochemical properties, and in vitro digestibility of BH starch. This fundamental information might be meaningful to enrich the theoretical basis of physical modification on BH starch and extend the applications of BH in the food industry.

Plasma Processing of Light- and Heavy-Oil Asphaltenes

The paper presents an analysis of the results of an experimental study of carbon materials obtained in a direct-current arc plasma from asphaltenes isolated from light oil of the Sredneugutskoye field and combined heavy oil from Venezuelan fields, as well as asphaltenes isolated from natural asphaltite. The influence of the composition of initial asphaltenes on the composition and properties of carbon materials obtained as a result of plasma treatment has been studied. The parent asphaltenes and carbon materials synthesized from them have been examined using a set of instrumental methods: X-ray diffraction, thermogravimetric analysis, energy-dispersive X-ray fluorescence analysis, Fourier-transform IR spectroscopy, X-ray photoelectron spectroscopy (XPS), transmission and scanning electron microscopy, and laser diffraction. Changes in the composition and structure of the obtained materials after plasma processing of asphaltenes have been established. It is shown that this method can be considered promising for processing not only petroleum material, but also oil industry waste enriched in resin–asphaltene components.

Diffusion coefficient and the volume swelling of CO2/light oil systems: Insights from dynamic volume analysis and molecular dynamics simulation

The oil volume expansion and CO2 diffusion are one of the main mechanism of CO2-enhanced oil recovery (CO2-EOR). This paper established a series of experiments, numerical simulations, and molecular dynamics (MD) simulations to describe mass transfer behaviors between oil–gas phases. Expressly, the CO2 diffusion coefficient and light oil swelling factor are signification parameters to quantify and analyze these behaviors. In detail, the CO2 diffusion coefficient and the oil swelling factor were obtained from the traditional pressure decay method and the advanced MD simulation. Synthetically, the pressure decay method and MD simulation results were mutually verified. The results showed that the equilibrium pressure was proportional to the mole fraction of CO2 and inversely proportional to the mole fraction of light oil. The equilibrium time was proportional to the mole fraction of CO2 and light oil. At the temperature of 333.15 K and the initial pressure of 7.5 MPa, the CO2 diffusion coefficient in light oil was positively correlated with the relative molar proportion of CO2, while the light oil swelling factor was vice versa. In addition, the closer to the CO2-light oil interface, the greater the light oil's potential energy and self-diffusion coefficient, and the stronger the transport ability.

A Systematic Experimental Study to Understand the Performance and Efficiency of Gas Injection in Carbonate Reservoirs

Summary Gas injection is the most widely applied recovery method in light, condensate, and volatile oil carbonate reservoirs. Gas has high displacement efficiency and usually results in a low residual oil saturation in the part of the reservoir that is contacted with gas. The displacement efficiency increases when the injected gas is near-miscible or miscible with the oil. In addition to nitrogen and hydrocarbon gas projects, carbon dioxide (CO2) enhanced oil recovery (EOR) has been the dominant gas EOR process. Gas-based EOR has been implemented in both mature and waterflooded carbonate reservoirs. In this paper, we present the results of a detailed experimental study aimed at understanding the performance and efficiency of gas injection in carbonate reservoirs. A series of immiscible and miscible gas injection coreflood experiments were performed using limestone reservoir cores under different injection strategies. To minimize laboratory artifacts, long cores were used in the experiments, and to observe the effect of gravity, both 2 in. diameter and 4 in. diameter (whole core) were used. The experiments were performed under reservoir conditions using live crude oil. The core wettability was restored by aging the core in crude oil for several weeks under reservoir temperature. Hydrocarbon gas (methane) was used as the immiscible injectant, and both CO2 and a mixture of 50% C1 and 50% CO2 were used as miscible injectant. All gas injection experiments were performed using vertically oriented cores, and the gas was injected from the top unless it is stated otherwise. The main parameters investigated in this study are as follows: The effect of miscibility on oil recovery for both continuous gas injection and water alternating gas (WAG). The effect of gravity on gas sweep efficiency compared to waterflooding. The effect of gas-oil interfacial tension (IFT) on oil recovery when using the same oil. The effect of oil type on oil recovery using the same injected gas at miscible and immiscible conditions. The effect of immiscible gas injection on subsequent miscible gas injection performance. Impact of CO2 cycle length on ultimate oil recovery. The impact of the order of fluid injection where multiple WAG injection cycles were performed in separate experiments after water or gas injection. The main conclusions of this study are as follows: As expected, miscibility has a significant impact on displacement efficiency and oil recovery where miscible gas recovered more than 20% extra oil compared to immiscible gas. A significant variation in oil recovery is observed for miscible gas injection (i.e., more than 10 saturation units difference) depending on the minimum miscibility pressure (MMP) between the injected gas and crude oil, even when both experiments are performed at miscible conditions using the same injected gas. The performance of tertiary CO2 flood was adversely affected by the slug of immiscible gas injected. Therefore, it is not recommended to have immiscible gas injection before miscible gas injection. Regardless of injected gas type, gas injection with similar IFTs achieved similar oil recovery. During WAG experiments, starting the injection cycles with water or gas did not have any impact on the ultimate oil recovery for both miscible and immiscible cases for one of the reservoirs, while WAG_G (WAG starting with gas injection) recovered more oil for another reservoir. Gravity has a significant impact on oil recovery for both miscible and immiscible gas injections. A significant difference is observed in oil recovery when comparing CO2 injection on 2-in.- and 4-in.-diameter core samples or when comparing horizontal vs. vertical immiscible gas injection and WAG experiment. The longer the CO2 slug size, the higher the oil recovery observed in gas injection experiments. The results of this study provide a rich and rarely available set of experimental data that can help improve and optimize gas and WAG injection in oil-wet carbonates.

EVALUATION OF TOXICITY FOR MYSIDOPSIS JUNIAE SPECIES IN CASES OF OIL SPILL IN THE BRAZILIAN POTIGUAR BASIN

This study aimed to assess the toxicity of the water soluble fraction (WSF) and correlate the effects of three oils and their compositions, through the bioassay with the Mysidopsis juniae, the analysis of n-alkanes and specific gravity. The PET01 and PET02 oils were classified as light oils ºAPI 39.8 and 32.8 and paraphynics with more abundant n-alkane ranges from n-C10 to n-C16, and n-C9 to n-C32. The PET03 oil was classified as heavy (°API 19.7), with more abundant hydrocarbons in the range of n-C29 and n-C33. It was also possible to evaluate the concentrations of metals in petroleum, Ba (3.41-4.45 mg/kg), Fe (5.42-9.01 mg/kg), Zn (0.18-0.53 mg/kg) and Ni (1.77-3.55 mg/kg) were present in the composition and may have harmful effect even at low concentrations. The acute toxicity of WSF from the oils varied by oil type, with LC50 11.4-27.6 of % WSF. Spill simulations indicated that short-term exposures in areas spilled with these oils are less toxic, but with increasing oil and seawater contact time (>1 h), the toxicity and solubility of total BTEX increases. The toxicity of the samples was directly related to the composition of the oils and categorized by the ecotoxicological risk to the environment from PET01 > PET02 > PET03. These results provide reliable data for ecotoxicological risk assessments in cases of oil spillage in marine environments.

Evaluation of compositional models and PVT correlations for Iraqi light crude oils properties

AbstractEvaluation of common compositional models and pressure–volume–temperature (PVT) correlations are carried out against field data for light crude oil from north Iraqi reservoirs. The reported data and the evaluation are significant to the petroleum industry, as various international and local oil companies operate in this region. The comprehensive PVT program Multiflash™ 7.2 is utilized, employing the Peng–Robinson (PR) and Redlich–Kwong–Soave (RKS). The oil formation volume factor, bubble point pressure, solution gas–oil ratio (Rso), and saturated oil viscosity are chosen for this evaluation. The results demonstrate that the PR and RKS compositional models, with some adjustments, exhibit much higher accuracy as compared to PVT correlations. For example, the errors between the model's predictions and the field data for the Rso are 9% for PR ad 17% for the RKS model. In contrast, for the PVT correlations, much higher errors are obtained. The lowest errors (32%) are obtained with the Ikiensikimama and Ajienka, while above 90% errors (the highest) are reported by Petrosky and Farshad. This study will enable the petroleum industry to improve and optimize the production operations in north Iraq–Kurdistan region.

Modified PU sponge for water purification

In this paper, poly-dopamine modified PU sponges were applied for water purification after being modified by different chemicals. Ag NPs were firstly in situ reduced on a polydopamine–modified polyurethane (PU) sponge under mild conditions (PU–PDA–Ag). Ag NPs could be uniformly dispersed and securely immobilized on the skeleton of PU sponge, which efficiently maintained the catalytic activity and stability. The soluble organic pollutants could be catalytically reduced by the PU–PDA–Ag sponge with the appearance of NaBH4. The target organic pollutants, including methylene blue (MB), methyl orange (MO), rhodamine B (RhB), and 4–nitrophenol (4–NP) could be completely reduced. In addition, the PU–PDA–Ag sponge was recycled for five cycles without a notable decrease in catalytic activity for the reduction of MB, exhibiting excellent reusability. To reverse the surface wetting characteristics for oil–water separation, the PU–PDA–Ag sponge was covalently grafted with mercaptan (dodecanethiol) to form a superhydrophobic/superoleophilic sponge (WCA=157.5°, OCA=0 °). The superhydrophobic/superoleophilic sponge (PU–PDA–Ag–SH) presented excellent sorption capacity in the range of 21.6–101.2 g/g for various insoluble oils and organic solvents and also showed superior reusability, which could be reused for 20 cycles without a significant decrease in sorption capacity. The PU–PDA–Ag–SH also provided the capability of continuous oil–water separation for both light oils and heavy oils with separation efficiency as high as 98.35% for diesel and 99.38% for chloroform, respectively.

Origin of the Ultra-Deep Hydrocarbons from the Shunbei No. 1 Fracture Zone in the North of Shuntuoguole Low Uplift, Tarim Basin, North-Western China

In order to have a deeper insight into the accumulation mechanism of ultra-deep hydrocarbons, in this paper, the recently discovered ultra-deep Ordovician light oil and gas deposits (>7200 m) in the Shunbei No. 1 fracture zone are studied intensively, including maturity, source kitchens, the extent of secondary alterations, and possible migration directions, based on an analysis of the molecular compositions and stable carbon isotopes of crude oils and natural gases. The average equivalent vitrinite reflectance (Rc) of these oils, estimated from light hydrocarbons (H versus I), MDI, DNR, and MDR, are about 1.50%, 1.58%, 1.48%, and 1.51%, respectively, which suggests that most of the oils are in the late stages of crossing the oil window. The two maturity grades (1.06–1.25% and 1.36–1.67%) of the oil samples calculated from the aromatic compounds indicate the presence of at least two stages of hydrocarbon charge. In addition, the positive correlation plot of DNR and MDR (y = 3.59x − 12.84; R2 = 0.96) indicates that oils in the southwestern region of the F1 (S1-11–S1-16) are slightly more mature than oils in the northeastern region of the F1 and the well at SL1, far from the No. 1 main fault zone. In addition, the study shows that these hydrocarbons belong to the same source kitchen of a reduced marine sedimentary environment with mixed organic matter comprising benthic and planktonic algae, based on biomarker parameters, light hydrocarbons, and carbon isotope compositions. The oil–oil correlation analyses suggest that the studied oil samples are probably derived from the in situ Lower Cambrian Yuertusi formation source rocks. Various geochemical parameters consistently show limited significant hydrocarbon alteration processes, indicating favorable preservation conditions in the study area. The integrated geochemical characteristics of the hydrocarbons allow us to infer that they mainly migrate vertically from the in situ Lower Cambrian Yuertusi formation source rocks toward the Ordovician reservoirs, followed by a certain degree of lateral migration from southwest to northeast.

Physical properties variation of crude oil under natural laboratory and its geological implications: Dongying Sag, eastern China

The Dongying Sag in eastern China is a mature exploration area and contains a wide variety of accumulations ranging from extra heavy oil to light oil. This multi-source lacustrine rift basin provides meaningful insights into the relationships between organofacies, maturity, charging, mixing, and oil properties. The Es3 source rocks are in the immature to mid-mature stage, while the Es4 source rocks are in the immature to late mature stage. Among them, Es4 source rocks were deposited in an anoxic, stratified, brackish water environment. Based on the kinetic model, it appears that the oil generation rate of Es4 source rocks is higher than that of Es3 source rocks, and the oil generation time of Es4 source rocks was earlier than that of Es3 source rocks. Whether in Es4 or Es3 members, source rocks with the kerogen type I have the greatest oil yield compared with other kerogens. The variations in oil physical and geochemical properties can be attributed to differences in organofacies and thermal maturity, which is in agreement with the results of source rock geochemistry and macerals analysis. Because the concentrations of maturity-related biomarkers or non-biomarkers show several orders of magnitude variation across maturity windows, these maturity parameters do not reliably characterize the maturity signals in mixed oil scenarios. Maturity parameters based on biomarker ratios can produce biases that overemphasize the contribution of low maturity oils and thus track the signals of low maturity end-member oils. In contrast, maturity parameters based on aromatic isomers are more sensitive to mixing processes and reflect the mixing degree of the accumulated oils. The same series of maturity parameters can track hydrocarbon migration pathways and relative maturity, while multiple series of maturity parameters can reconstruct hydrocarbon charging and mixing histories.