Linhares, Vanessa do Nascimentode Araujo, Leandro GoulartVicente, RobertoMarumo, Julio Takehiro...
10页
查看更多>>摘要：Surfactant-based technologies have been studied for the treatment of radioactive waste containing isotopes of radium. Nevertheless, the use of combined processes to remove radium from radioactive oil sludge is scarce in the literature. The objective of this work was to investigate the potential of a non-ionic surfactant to remove radium from raw oil sludge (ROS) and pre-treated, microwave-irradiated oil sludge (POS). Characterization of ROS and POS was made using the following methods: Thermal Gravimetric Analysis, X-ray diffraction, Scanning Electron Microscopy coupled with Energy-Dispersive X-ray Spectroscopy, and gamma spectrometry. The effects of surfactant concentration (0.5-7.5%), temperature (25-60 degrees C), and contact time (30 and 60 min) were investigated. For ROS, little or no influence on the decontamination process was found for variations in the selected process parameters. For POS, the lowest surfactant concentration (2.5%) was the most efficient, removing about 94% of 226Ra and 228Ra. Neither contact time nor temperature affected removal. For ROS, removal percentages were 50-60% for 226Ra and 35-45% for 228Ra. The results indicated that the surfactant acted more efficiently in the decontamination of POS.
Sadeghtabaghi, ZahraRabbani, Ahmad RezaHemmati-Sarapardeh, Abdolhossein
11页
查看更多>>摘要：The level of crude oil thermal maturity has so far been done using biomarker ratios. Despite valuable geochemical information provided by biomarker ratios, they usually face problems in thermal maturity assess-ment. This paper aims to introduce new indexes for thermal maturity assessment. For this purpose, three crude oil samples were heated at 100 degrees C for a while and then sampled. The asphaltene fractions of heated samples were analyzed by XRD and FTIR methods after precipitation. The variations of derived indexes from diffractograms and spectra indicate that aromaticity, the average diameter of aromatic sheets, and branched index increase during the heating process. In contrast, the average height perpendicular to the aromatic sheets and subsequently the average number of aromatic sheets decrease. Since these variations are concerning time and temperature, they can be considered as thermal maturity indicators. These alterations are also consistent with previous re-searches. In this paper, the thermal maturity of eight Iranian crude oil samples, which biomarker ratios were unable to determine their thermal maturity level, has been assessed using these novel indicators for the first time. These crude oil samples belong to three distinct genetic groups, and thermal maturity has been evaluated in all families. In the first genetic group, the Fahliyan reservoir has more mature crude oil samples than the crude oil sample of the Kazhdumi reservoir. In the second group, the Buwaib sample possesses more maturity level than Khatiah crude oil. Eventually, the Sarvak reservoir contains more mature crude oil than two other Kazhdumi samples. The final results are compatible with the other data, such as reservoir depth and API.
查看更多>>摘要：Stimulated reservoir volume (SRV) is the most critical index to represent the hydraulically fractured volume after stimulation. The existing models using microseismic events usually lack a sufficient unified basis on the geo-metric definition, leading to significant differences in SRV calculation and interpretation. This paper has generally conducted the classification and the evaluation for the existing models and the newly proposed model. According to three typical grid structures, we firstly divided SRV models into three categories: boundary-based, voxel-based, and density-based. Three typical SRV calculation methods are also proposed based on the alpha shape method, the voxel discretization, and the octree decomposition. Then, we have developed an integrated workflow based on synthetic events to evaluate their performance quantitatively under different fracture configurations and noise ratios. Through a large number of simulated calculations, it is indicated that the density-based method outperforms the other two methods in accuracy, adaptability, and anti-noise ability for complex fracture networks with different configurations. Besides, the engineering application has also its practicability and superiority in generating more refined grid structures. This paper attempts to summarize and evaluate the existing methods and proposes new methods based on the classification. It would provide helpful guidance for developing more superior SRV calculation methods.
查看更多>>摘要：Salt rock is a potential medium for the underground storage of hydrocarbons and nuclear waste. In China, salt deposits are typically composed of layered rocks, usually sandwiched by insoluble interlayers. These salt rock -gypsum interlayers significantly affect the integrity of bedded salt caverns. Therefore, it is important to assess how the permeability and porosity of salt interlayers in an excavation damage zone (EDZ) evolve at high temperatures and triaxial stress/seepage pressures. To address this, in this study, we have developed a triaxial testing system that uses thermo-hydro-mechanical-chemical (THMC) coupling. Then, the permeability and porosity of salt rock-gypsum interlayers with 0.6-0.9 degrees of damage (i.e.after being subjected to a triaxial stress of 60-90% of the triaxial compressive strength; the confining pressure is 25 MPa and experimental temperature is 20 degrees C) under a coupled THMC environment were measured. The results show that the permeability and porosity of gypsum with the four different damage degrees do not increase monotonically with increasing temperature under the coupled THMC condition. Especially for the 0.6 and 0.8 damaged gypsum specimens, the permeability and porosity tend to decrease in the temperature range of 300-500 degrees C. For the 0.8 and 0.9 damaged gypsum specimens, a vertical and catastrophic increase in permeability and porosity is observed at 550 degrees C and 300 degrees C, respectively. The variation trends of the permeability and porosity of the damaged specimens are closely related to the combined effects of the triaxial stress, seepage pressure, thermal stress, and degree of damage.
查看更多>>摘要：Research on the migration and accumulation of hydrocarbons in shale oil reservoirs composed solely of organicrich mudstones has not received adequate attention. The Qianjiang Formation provides an opportunity for research on the hydrocarbon accumulation mechanism due to the presence of hydrocarbon migration characteristics in its inter-salt organic-rich fine-grained rocks. In this study, the inter-salt stratum of the tenth rhythmite can be classified into three sections: lower, middle, and upper. The middle section is mostly composed of laminated marlstones and laminated calcite-bearing argillaceous dolomicrites, whereas, the lower and upper sections mostly contain bedded muddy dolomicrites and glauberite. Geochemical analysis was conducted to study the organic matter enrichment mechanism and shale oil accumulation characteristics. The results indicate that the middle section has the highest organic matter abundance, with poor organic matter abundance displayed by the other sections. The C27/C29 sterane and extended tricyclic terpane ratios suggest that the organic matter types in different sections of the inter-salt stratum differ, and the middle section has more aquatic organic matter than other sections. The sedimentary structures and salinity-related parameters indicate that the middle section was developed in a deep stratified saline lake and that the other sections were formed in a shallow hypersaline lake. This study shows that high biological productivity and stratified lake water facilitated the enrichment of organic matter, resulting in high organic matter content in the middle section. The oil saturation index and hydrocarbon composition suggest that hydrocarbons were differentially accumulated in the inter-salt stratum of the tenth rhythmite. The maturity-related biomarkers further revealed the possible migration paths of hydrocarbons in the inter-salt stratum. Based on the aforementioned analyses, this study established an inter-salt shale oil accumulation model. This study suggests that hydrocarbons were released from the mature source rocks in the deep depression with differential migration laterally and vertically within the inter-salt stratum. The study of the Qianjiang Depression shows that organic-rich fine-grained rocks cannot only form in situ sweet spots but may also possess migrated hydrocarbons inside them, which are characterized by high organic matter abundance and oil saturation. This research provides a new case for further understanding hydrocarbon accumulation inside source rocks.
查看更多>>摘要：We study the applicability of Generative Adversarial Networks (GANs) for generating the synthetic data related to well construction and geological characterisation of the near-wellbore area. We focus on 1D mud logs (time series) and 2D core images. GANs are known to have difficulties with their quality assessment in general. Moreover, generic GAN's performance assessment methods cannot be suitable for the petroleum domain. A petroleum engineer expects the GANs to generate data with specific physical and geological properties, not just a colourful picture. We have trained over 40 GAN models and generated synthetic data with them. Then, we have involved several experts to analyse the generated data in order to address the question of whether it is possible to substitute human analysis with a mathematical metric. We found that some quantitative mathematical metrics can represent our experts' perceptions. In particular, we show that for 2D core images, Mode Score metric with standard inception v3 model is the best proxy for all considered qualitative metrics of expert's perception according to the Kendall correlation (for two qualitative metrics the correlation is strong, the absolute value is above 0.7, and for other two it is moderate, the absolute value is between 0.5 and 0.7); for mud logs time-series, Mode Score and Frechet Inception Distance with the InceptionTime model provide the strong (above 0.7) correlation with objects reconstruction quality, whereas Inception Score has almost strong correlation (with Kendalls'-tau coefficient 0.69) with experts' perception of objects generation quality. With these results, experts manual annotation of generated objects during GAN model selection process can be reduced to calculating the corresponding quantitative metrics.
查看更多>>摘要：Multi-lateral well construction is in high demand in both petroleum industrial and commercial sectors. Compared with the traditional gel-breaking fluids used in multi-lateral well completion, autonomously self-gel-breaking completion fluids in a certain downhole environment have specific challenges in development and performance. In this work, focus was on self-gel-breaking capacity demonstrating controllably heat-triggered self degradation of rheological modifier involved in the newly constructed completion fluid. The self-degradation strategy was first analyzed for the fundamental polymeric additives, and then xanthan gum with a high pyruvate content, as the most crucial rheological additive, was provided of special conformational transition from helix to lattice structure due to sidechain mutual repulsion effect, in combination to tests of advanced technologies such as molecular weight, infrared spectroscopy, dynamic viscosity, elastic modulus, and micromorphology. This facile strategy can be applicable for the control of xanthan thermal degradability that directly responses to self-gel-breaking capability of completion fluid. Finally, several key performance such as reservoir protection and self-gel-breaking capability for the newly developed completion fluid were evaluated to validate its promising gel-free application in the construction of multi-lateral wells.
查看更多>>摘要：Appraisal well testing plays a key role in optimizing a complex field's exploitation strategy - and increasing complexity often calls for more elaborate reservoir models for the proper interpretation of each test's results. The classical analytical methods usually require restrictive simplifying assumptions, which limit their usefulness when dealing with reservoir heterogeneity. We seek to solve this issue by applying the hybrid analytical-numerical Generalized Integral Transform Technique (GITT) to the pressure diffusivity equation - and specifically, to the point-source problem extended to a reservoir with arbitrary permeability variation irregularly distributed throughout the 3D domain. The technique is first demonstrated to produce an exact alternative form of the well-known solution to the classical point-source in a homogeneous reservoir. This equivalence is then used to derive a computationally efficient working expression for the generalized point source in a heterogeneous reservoir. Finally, this building block is applied to construct a uniform flow solution for a limited entry vertical well through spatial superposition - thus demonstrating the usage of the GITT for other wellbore geometries. Synthetic examples are used to show that the obtained expressions are in good agreement with results from a commercial reservoir simulator. In all cases presented, the eigenfunction expansions for both the drawdown pressure and its logarithmic derivative converge to at least four and two significant digits, respectively, within the adopted practical ranges of the series' truncation orders. It is clear that the pressure expansions have better convergence characteristics, which are also influenced by the time value and by the distance from the position under consideration to the point-source. The resulting novel solution to the point-source provided in the present work is the most general and least restrictive expression presented so far to this single problem in a heterogeneous domain, and it is suitable for pressure transient analysis.
查看更多>>摘要：Bleaching of red beds, a type of hydrocarbon-induced alteration, is generally attributed to redox reactions between ferric iron minerals and hydrocarbon-bearing solutions. Herein, we report sandstone bleaching occurs interbedded with the coal- and dark mudstone-bearing strata at shallow depths below two unconformity surfaces separating sandstone formations of Triassic-Jurassic age in the Ordos Basin, China. Field observations, petrography, and geochemistry suggest that uplift events controlled the formation of red beds via supergene alteration and bleaching via hydrocarbon circulation. The color of sandstones below the unconformities grade from red, yellow, and white colors at shallow depths (few meters to tens of meters) to dark yellow, gray-green and gray colors at deeper depths. Organic matter (carbonaceous plant debris) and pyrite in the unaltered sandstone gave rise to the gray color. The red/yellow sandstones are characterized by the presence of extensive iron oxide/ hydroxide grain coatings, exhibit intense dissolution and extensive kaolinization of detrital feldspar and biotite and lithics and are mainly composed of detrital quartz. The white, bleached sandstone presents similar petrographic characteristics as the unbleached sandstone except for a lack of iron oxide/hydroxide cements. 818OVSMOW (9.8%, to 15.8%,) and 8DVSMOW (- 103%, to -119%,) values of kaolinite, and chemical indices of alteration of sandstones indicate a weathering origin for the kaolinite and the dissolution of labile minerals in the red and yellow sandstones. The original color of the bleached sandstone was gray during very early diagenesis and shifted to red/yellow due to the oxidation of pyrite and ferromagnesian silicate minerals (e.g., biotite) into hematite or goethite cements by the meteoric water circulation during regional uplift following the deposition of each formation. Supergene alteration associated with unconformities also created significant secondary porosity, and allowed later hydrocarbons to flow along the unconformities. The lithological properties of the weathered rocks below unconformities are highly heterogeneous both vertically and laterally and have a significant influence on fluid flow. This study provides direct evidence for hydrocarbon migration along unconformities and improves understanding of fluid-rock interaction in subsurface reservoirs.
Jo, SuryeomAhn, SeonginPark, ChanghyupKim, Jaejun...
20页
查看更多>>摘要：This paper presents a new deep-learning-based generative method applicable to history matching without an inverse scheme. Multiple-point geostatistics is used to construct a prior population stochastically. A convolutional variational autoencoder (VAE) with probabilistic latent space is trained as the generative method, and kmeans clustering, nondominated sorting, and multilevel geomodel generations are performed based on flow responses. The applicability of the developed workflow was confirmed using a waterflooding problem with multiple wells in fluvial channel reservoirs. The VAE generates new geomodels based on the latent features and builds equiprobable models neighboring the representative models that reflect the observed production performance. The geomodels match the oil production profiles reliably as the steps progress and accurately forecast the water breakthrough time and liquid production trajectories. The density map of plausible geomodels explains reasonably the uncertainty of channel connectivity. The structural similarity index confirms that the generated geomodels become similar to the target reservoir and thus that the developed VAE-based framework creates geomodels that preserve geological realism. This proposed method involves relatively less time-consuming simulations without any inverse or optimization processes; nonetheless, it generates plausible geomodels in dimensionality-reduced latent space. The study methods and findings are thus applicable to scale-variant data integration and uncertainty assessment.
NSTL
Elsevier