Petroleum Science最新文献

{"title":"An intelligent drilling guide algorithm design framework based on highly interactive learning mechanism","authors":"Yi Zhao ,&nbsp;Dan-Dan Zhu ,&nbsp;Fei Wang ,&nbsp;Xin-Ping Dai ,&nbsp;Hui-Shen Jiao ,&nbsp;Zi-Jie Zhou","doi":"10.1016/j.petsci.2025.05.019","DOIUrl":"10.1016/j.petsci.2025.05.019","url":null,"abstract":"<div><div>Measurement-while-drilling (MWD) and guidance technologies have been extensively deployed in the exploitation of oil, natural gas, and other energy resources. Conventional control approaches are plagued by challenges, including limited anti-interference capabilities and the insufficient generalization of decision-making experience. To address the intricate problem of directional well trajectory control, an intelligent algorithm design framework grounded in the high-level interaction mechanism between geology and engineering is put forward. This framework aims to facilitate the rapid batch migration and update of drilling strategies. The proposed directional well trajectory control method comprehensively considers the multi-source heterogeneous attributes of drilling experience data, leverages the generative simulation of the geological drilling environment, and promptly constructs a directional well trajectory control model with self-adaptive capabilities to environmental variations. This construction is carried out based on three hierarchical levels: “offline pre-drilling learning, online during-drilling interaction, and post-drilling model transfer”. Simulation results indicate that the guidance model derived from this method demonstrates remarkable generalization performance and accuracy. It can significantly boost the adaptability of the control algorithm to diverse environments and enhance the penetration rate of the target reservoir during drilling operations.</div></div>","PeriodicalId":19938,"journal":{"name":"Petroleum Science","volume":"22 8","pages":"Pages 3333-3343"},"PeriodicalIF":6.1,"publicationDate":"2025-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145048254","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The genesis and accumulation mechanism of CBM in the typical mid- to low-rank coal-bearing basins","authors":"Bin Zhang ,&nbsp;Shu Tao ,&nbsp;Fan Yang ,&nbsp;Yi Cui ,&nbsp;Qing-He Jing ,&nbsp;Jie Guo ,&nbsp;Shi-Da Chen ,&nbsp;Yi-Jie Wen ,&nbsp;Xin-Yang Men","doi":"10.1016/j.petsci.2025.04.017","DOIUrl":"10.1016/j.petsci.2025.04.017","url":null,"abstract":"<div><div>The composition and isotopic characteristics of coalbed methane (CBM), as well as the genesis of CH₄ and CO₂, associated geological process and migration-accumulation model of CBM in typical mid- to low-rank coal-bearing basins were studied. The genesis of CBM is jointly influenced by the degree of coalification and biochemical processes, which in turn determine the composition and isotopic characteristics of CBM. Biogenic gas is extensively developed in mid- to low-rank coal-bearing basins, but its genesis varies. In the Baode area, China, and the San Juan Basin, USA, CBM is mainly secondary biogenic gas and thermogenic gas. In the Miquan area, China, CBM is characterized by primary biogenic gas. However, CBM in the Jiergalangtu area, China, Surat Basin, Australia, and Power River Basin, USA, are characterized by secondary biogenic gas. Microbial CO₂ reduction occurs in these coal-bearing basins, but with significant gas generation by acetate fermentation in some areas of these basins. Moreover, CO₂ in the Power River Basin, Surat Basin, and Jiergalangtu area mainly originates from microbial degradation of organic matter. However, in other basins studied, CO₂ initially derives from coal pyrolysis and is subsequently supplemented by CO₂ from microbial methanogenesis. The generation and isotope fractionation of CBM are affected and controlled by associated geological processes. Additionally, under the control of tectonic morphology and hydrogeological conditions, the genesis and migration-accumulation models of CBM in mid- to low-rank coal-bearing basins can be summarized into two models—the hydrodynamic active monoclinic model and the hydrodynamic differential syncline model—or a combination of the two.</div></div>","PeriodicalId":19938,"journal":{"name":"Petroleum Science","volume":"22 8","pages":"Pages 3069-3085"},"PeriodicalIF":6.1,"publicationDate":"2025-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145048702","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Analysis of seismic dispersion and attenuation for gas-hydrate formations in the South China Sea","authors":"Zuo-Xiu He ,&nbsp;Feng Zhang ,&nbsp;Pin-Bo Ding ,&nbsp;Xiang-Yang Li ,&nbsp;Hai-Feng Chen","doi":"10.1016/j.petsci.2025.05.008","DOIUrl":"10.1016/j.petsci.2025.05.008","url":null,"abstract":"<div><div>Existing studies indicate that gas hydrate-bearing formations exhibit notable seismic velocity dispersion and attenuation. The Shenhu area of the South China Sea hold significant gas hydrate resource potential; however, the relationship between seismic velocity dispersion, attenuation properties, and gas-hydrate saturation remains insufficiently understood. Furthermore, a significant mismatch exists between the real seismic angle gather near a well and the synthetic angle gather generated using the convolution method, and this discrepancy may arise from the seismic velocity dispersion and attenuation characteristics of the gas hydrate-bearing formations. In this paper, we develop a rock physics model that integrates White's and Dvorkin's models, accounting for varied types of gas-hydrate occurrence states, specifically tailored to the gas hydrate-bearing formations in the Shenhu area. This model is calibrated with well log data and employed to investigate how gas-hydrate saturation influences seismic velocity dispersion and attenuation. Numerical analysis reveals the coexistence of two types of gas-hydrate occurrence states in the region: high gas-hydrate saturation formations are dominated by load-bearing-type gas hydrate, and formations containing both gas hydrate and free gas may exhibit either load-bearing or pore-filling types. The seismic velocity dispersion and attenuation properties vary significantly depending on the gas-hydrate occurrence state. We further apply the proposed model to generate seismic velocity and attenuation logs at various frequencies. These logs are used in seismic forward modeling employing both the convolution method and the propagator matrix method. Well tie analysis indicates that the synthetic angle gather incorporating attenuation via the propagator matrix method aligns more closely with the real seismic angle gather than the convolution method. This study provides valuable insights into frequency-dependent amplitude versus offset (AVO) analysis and the seismic interpretation of gas hydrate-bearing formations in the South China Sea.</div></div>","PeriodicalId":19938,"journal":{"name":"Petroleum Science","volume":"22 8","pages":"Pages 3279-3292"},"PeriodicalIF":6.1,"publicationDate":"2025-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145048186","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A large-scale, high-quality dataset for lithology identification: Construction and applications","authors":"Jia-Yu Li ,&nbsp;Ji-Zhou Tang ,&nbsp;Xian-Zheng Zhao ,&nbsp;Bo Fan ,&nbsp;Wen-Ya Jiang ,&nbsp;Shun-Yao Song ,&nbsp;Jian-Bing Li ,&nbsp;Kai-Da Chen ,&nbsp;Zheng-Guang Zhao","doi":"10.1016/j.petsci.2025.04.013","DOIUrl":"10.1016/j.petsci.2025.04.013","url":null,"abstract":"<div><div>Lithology identification is a critical aspect of geoenergy exploration, including geothermal energy development, gas hydrate extraction, and gas storage. In recent years, artificial intelligence techniques based on drill core images have made significant strides in lithology identification, achieving high accuracy. However, the current demand for advanced lithology identification models remains unmet due to the lack of high-quality drill core image datasets. This study successfully constructs and publicly releases the first open-source Drill Core Image Dataset (DCID), addressing the need for large-scale, high-quality datasets in lithology characterization tasks within geological engineering and establishing a standard dataset for model evaluation. DCID consists of 35 lithology categories and a total of 98,000 high-resolution images (512 × 512 pixels), making it the most comprehensive drill core image dataset in terms of lithology categories, image quantity, and resolution. This study also provides lithology identification accuracy benchmarks for popular convolutional neural networks (CNNs) such as VGG, ResNet, DenseNet, MobileNet, as well as for the Vision Transformer (ViT) and MLP-Mixer, based on DCID. Additionally, the sensitivity of model performance to various parameters and image resolution is evaluated. In response to real-world challenges, we propose a real-world data augmentation (RWDA) method, leveraging slightly defective images from DCID to enhance model robustness. The study also explores the impact of real-world lighting conditions on the performance of lithology identification models. Finally, we demonstrate how to rapidly evaluate model performance across multiple dimensions using low-resolution datasets, advancing the application and development of new lithology identification models for geoenergy exploration.</div></div>","PeriodicalId":19938,"journal":{"name":"Petroleum Science","volume":"22 8","pages":"Pages 3207-3228"},"PeriodicalIF":6.1,"publicationDate":"2025-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145048189","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Study on S-wave velocity prediction in shale reservoirs based on explainable 2D-CNN under physical constraints","authors":"Zhi-Jun Li ,&nbsp;Shao-Gui Deng ,&nbsp;Yu-Zhen Hong ,&nbsp;Zhou-Tuo Wei ,&nbsp;Lian-Yun Cai","doi":"10.1016/j.petsci.2025.04.027","DOIUrl":"10.1016/j.petsci.2025.04.027","url":null,"abstract":"<div><div>The shear wave (S-wave) velocity is a critical rock elastic parameter in shale reservoirs, especially for evaluating shale fracability. To effectively supplement S-wave velocity under the condition of no actual measurement data, this paper proposes a physically-data driven method for the S-wave velocity prediction in shale reservoirs based on the class activation mapping (CAM) technique combined with a physically constrained two-dimensional Convolutional Neural Network (2D-CNN). High-sensitivity log curves related to S-wave velocity are selected as the basis from the data sensitivity analysis. Then, we establish a petrophysical model of complex multi-mineral components based on the petrophysical properties of porous medium and the Biot-Gassmann equation. This model can help reduce the dispersion effect and constrain the 2D-CNN. In deep learning, the 2D-CNN model is optimized using the Adam, and the class activation maps (CAMs) are obtained by replacing the fully connected layer with the global average pooling (GAP) layer, resulting in explainable results. The model is then applied to wells A, B1, and B2 in the southern Songliao Basin, China and compared with the unconstrained model and the petrophysical model. The results show higher prediction accuracy and generalization ability, as evidenced by correlation coefficients and relative errors of 0.98 and 2.14%, 0.97 and 2.35%, 0.96 and 2.89% in the three test wells, respectively. Finally, we present the defined <em>C</em>-factor as a means of evaluating the extent of concern regarding CAMs in regression problems. When the results of the petrophysical model are added to the 2D feature maps, the <em>C</em>-factor values are significantly increased, indicating that the focus of 2D-CNN can be significantly enhanced by incorporating the petrophysical model, thereby imposing physical constraints on the 2D-CNN. In addition, we establish the SHAP model, and the results of the petrophysical model have the highest average SHAP values across the three test wells. This helps to assist in proving the importance of constraints.</div></div>","PeriodicalId":19938,"journal":{"name":"Petroleum Science","volume":"22 8","pages":"Pages 3247-3265"},"PeriodicalIF":6.1,"publicationDate":"2025-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145048187","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Pressure transient behavior of fractured wells in multilayered tight gas reservoirs with heterogeneous properties and limited fracture height","authors":"Jing-Jing Guo,&nbsp;Chao-Zhi Jiang,&nbsp;Hai-Tao Wang,&nbsp;Lie-Hui Zhang","doi":"10.1016/j.petsci.2025.05.002","DOIUrl":"10.1016/j.petsci.2025.05.002","url":null,"abstract":"<div><div>Hydraulic fracturing and commingle production of multiple layers are extensively adopted in unconventional tight gas reservoirs. Accurate determination of parameters of individual layers in multilayered tight gas reservoirs is essential for well performance evaluation and development strategy optimization. However, most analytical models for fractured vertical wells in stratified gas reservoirs focus on fully penetrated hydraulic fractures, neglecting the influence of partial penetration of hydraulic fractures. This paper presents a semi-analytical model to investigate the transient pressure behavior of vertically fractured wells in dual porosity multi-layered tight gas reservoirs. The partial penetration of hydraulic fracture, the vertical heterogeneities of layer properties, the differences between hydraulic fracture lengths in each layer and the stress sensitivity are all incorporated in the proposed model. The point-source solution, Laplace transformation, Fourier transformation, Pedrosa's transformation, perturbation technique, and the superposition principle are applied to obtain the analytical solution of transient pressure responses. The proposed model is validated against a commercial software, and the transient pressure behavior of vertically fractured wells in multi-layered tight gas reservoirs are analyzed. Based on the characteristics of the type curves, seven flow regimes can be identified, including wellbore storage, transitional flow period, reservoir linear flow period, vertical pseudo-radial flow in fracture system, inter-porosity flow period, late-time pseudo-radial flow period, and the boundary-dominated flow period. Sensitivity analyses reveal that the penetration ratio of hydraulic fracture has primary influence on early-time transient pressure behavior and production contribution, while the stress sensitivity mainly affects the late-time transient pressure behavior. Gas production at the initial stage is mainly contributed by the high-pressure/high-permeability layer, and gas backflow will occur during initial production stage for obviously unequal initial formation pressures. Finally, two field cases are conducted to illustrate the applicability of the proposed model. The model and corresponding conclusions can provide technical support for performance analysis of tight gas reservoirs.</div></div>","PeriodicalId":19938,"journal":{"name":"Petroleum Science","volume":"22 8","pages":"Pages 3357-3379"},"PeriodicalIF":6.1,"publicationDate":"2025-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145048249","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A new model for determining the effective permeability of tight reservoirs based on Fractal-Monte Carlo method","authors":"You Zhou ,&nbsp;Song-Tao Wu ,&nbsp;Ru-Kai Zhu ,&nbsp;Xiao-Hua Jiang ,&nbsp;Gan-Lin Hua","doi":"10.1016/j.petsci.2025.04.016","DOIUrl":"10.1016/j.petsci.2025.04.016","url":null,"abstract":"<div><div>In contrast to conventional reservoirs, tight formations have more complex pore structures and significant boundary layer effect, making it difficult to determine the effective permeability. To address this, this paper first proposes a semi-empirical model for calculating boundary layer thickness based on dimensional analysis, using published experimental data on microcapillary flow. Furthermore, considering the non-uniform distribution of fluid viscosity in the flow channels of tight reservoirs, a theoretical model for boundary layer thickness is established based on fractal theory, and permeability predictions are conducted through Monte Carlo simulations. Finally, sensitivity analyses of various influencing parameters are performed. The results show that, compared to other fractal-based analytical models, the proposed permeability probabilistic model integrates parameters affecting fluid flow with random numbers, reflecting both the fractal and randomness characteristics of capillary size distribution. The computational results exhibit the highest consistency with experimental data. Among the factors affecting the boundary layer, in addition to certain conventional physical and mechanical parameters, different microstructure parameters significantly influence the boundary layer as well. A higher tortuosity fractal dimension results in a thicker boundary layer, while increases in pore fractal dimension, porosity, and maximum capillary size help mitigate the boundary layer effect. It is also observed that the permeability of large pores exhibits greater sensitivity to changes in various influencing parameters. Considering micro-scale flow effects, the proposed model enhances the understanding of the physical mechanisms of fluid transport in dense porous media.</div></div>","PeriodicalId":19938,"journal":{"name":"Petroleum Science","volume":"22 8","pages":"Pages 3101-3118"},"PeriodicalIF":6.1,"publicationDate":"2025-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145048699","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Stepwise inversion method using second-order derivatives of elastic impedance for fracture detection in orthorhombic medium","authors":"Wei Xiang ,&nbsp;Xing-Yao Yin ,&nbsp;Kun Li ,&nbsp;Zheng-Qian Ma ,&nbsp;Ya-Ming Yang","doi":"10.1016/j.petsci.2025.04.026","DOIUrl":"10.1016/j.petsci.2025.04.026","url":null,"abstract":"<div><div>Reservoirs with a group of vertical fractures in a vertical transversely isotropic (VTI) background are considered as orthorhombic (ORT) medium. However, fracture detection in ORT medium using seismic inversion methods remains challenging, as it requires the estimation of more than eight parameters. Assuming the reservoir to be a weakly anisotropic ORT medium with small contrasts in the background elastic parameters, a new azimuthal elastic impedance equation was first derived using parameter combinations and mathematical approximations. This equation exhibited almost the same accuracy as the original equation and contained only six model parameters: the compression modulus, anisotropic shear modulus, anisotropic compression modulus, density, normal fracture weakness, and tangential fracture weakness. Subsequently, a stepwise inversion method using second-order derivatives of the elastic impedance was developed to estimate these parameters. Moreover, the Thomsen anisotropy parameter, epsilon, was estimated from the inversion results using the ratio of the anisotropic compression modulus to the compression modulus. Synthetic examples with moderate noise and field data examples confirm the feasibility and effectiveness of the inversion method. The proposed method exhibited accuracy similar to that of previous inversion strategies and could predict richer vertical fracture information. Ultimately, the method was applied to a three-dimensional work area, and the predictions were consistent with logging and geological a priori information, confirming the effectiveness of this method. Summarily, the proposed stepwise inversion method can alleviate the uncertainty of multi-parameter inversion in ORT medium, thereby improving the reliability of fracture detection.</div></div>","PeriodicalId":19938,"journal":{"name":"Petroleum Science","volume":"22 8","pages":"Pages 3229-3246"},"PeriodicalIF":6.1,"publicationDate":"2025-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145048188","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Full waveform inversion with fractional anisotropic total p-variation regularization","authors":"Bo Li ,&nbsp;Xiao-Tao Wen ,&nbsp;Yu-Qiang Zhang ,&nbsp;Zi-Yu Qin ,&nbsp;Zhi-Di An","doi":"10.1016/j.petsci.2025.05.004","DOIUrl":"10.1016/j.petsci.2025.05.004","url":null,"abstract":"<div><div>Full waveform inversion is a precise method for parameter inversion, harnessing the complete wavefield information of seismic waves. It holds the potential to intricately characterize the detailed features of the model with high accuracy. However, due to inaccurate initial models, the absence of low-frequency data, and incomplete observational data, full waveform inversion (FWI) exhibits pronounced nonlinear characteristics. When the strata are buried deep, the inversion capability of this method is constrained. To enhance the accuracy and precision of FWI, this paper introduces a novel approach to address the aforementioned challenges—namely, a fractional-order anisotropic total p-variation regularization for full waveform inversion (FATpV-FWI). This method incorporates fractional-order total variation (TV) regularization to construct the inversion objective function, building upon TV regularization, and subsequently employs the alternating direction multiplier method for solving. This approach mitigates the step effect stemming from total variation in seismic inversion, thereby facilitating the reconstruction of sharp interfaces of geophysical parameters while smoothing background variations. Simultaneously, replacing integer-order differences with fractional-order differences bolsters the correlation among seismic data and diminishes the scattering effect caused by integer-order differences in seismic inversion. The outcomes of model tests validate the efficacy of this method, highlighting its ability to enhance the overall accuracy of the inversion process.</div></div>","PeriodicalId":19938,"journal":{"name":"Petroleum Science","volume":"22 8","pages":"Pages 3266-3278"},"PeriodicalIF":6.1,"publicationDate":"2025-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145048255","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Comparison of original and de-asphalted crude oils during formation of HCl-induced emulsion and sludge","authors":"Ahmad Abbasi ,&nbsp;M. Reza Malayeri ,&nbsp;Maysam Mohammadzadeh-Shirazi","doi":"10.1016/j.petsci.2025.05.003","DOIUrl":"10.1016/j.petsci.2025.05.003","url":null,"abstract":"<div><div>Stable HCl-crude oil emulsion and its subsequent sludge formation, with detrimental impacts on oil production, may stem from acid stimulation. One major ambiguity in this process is to discern the most influential component of crude oil on the stability of formed emulsions. This fundamental question has not adequately been addressed in previous studies. In this work, the impact of de-asphalted part of crude oil (maltene) has been investigated on the acid-induced emulsion and sludge separately. Accordingly, the emulsion phase separation and the amount of formed sludge have been compared for four crude oils and their maltene samples for different concentrations of ferric ion and acidic pH values. The results of phase separation, as a criterion for emulsion stability, showed that crude oil samples formed 6 to 25 percent more stable emulsions than maltene samples, when using blank HCl. The emulsions of maltene and spent acid (pH = 2) broke completely during the first 15 min after emulsification. In addition, the maltene components usually had less contribution to sludge formation in the presence of blank HCl. It was concluded that asphaltene is the key component during interaction with HCl. However, the maltene of one crude sample formed higher acid sludge in comparison to its crude oil. For acid solutions containing 3000 ppm of ferric ion, the emulsion stability increased for all crude oil and maltene samples. Moreover, the stability of some maltene emulsions increased to 48% and 100% in the presence of 3000 ppm of ferric ions. The presence of ferric ions caused forming very stable emulsions, while most of the sludge formation took place at higher pH values. Finally, it was also attained that emulsion and sludge formations could happen simultaneously.</div></div>","PeriodicalId":19938,"journal":{"name":"Petroleum Science","volume":"22 8","pages":"Pages 3461-3471"},"PeriodicalIF":6.1,"publicationDate":"2025-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145048701","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}