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14 pages, 3919 KiB

Open AccessFeature PaperArticle

Water Saturation Prediction in the Middle Bakken Formation Using Machine Learning

by Ilyas Mellal, Abdeljalil Latrach, Vamegh Rasouli, Omar Bakelli, Abdesselem Dehdouh and Habib Ouadi

Eng 2023, 4(3), 1951-1964; https://doi.org/10.3390/eng4030110 - 11 Jul 2023

Cited by 2 | Viewed by 957

Abstract

Tight reservoirs around the world contain a significant volume of hydrocarbons; however, the heterogeneity of these reservoirs limits the recovery of the original oil in place to less than 20%. Accurate characterization is therefore needed to understand variations in reservoir properties and their [...] Read more.

Tight reservoirs around the world contain a significant volume of hydrocarbons; however, the heterogeneity of these reservoirs limits the recovery of the original oil in place to less than 20%. Accurate characterization is therefore needed to understand variations in reservoir properties and their effects on production. Water saturation (Sw) has always been challenging to estimate in ultra-tight reservoirs such as the Bakken Formation due to the inaccuracy of resistivity-based methods. While machine learning (ML) has proven to be a powerful tool for predicting rock properties in many tight formations, few studies have been conducted in reservoirs of similar complexity to the Bakken Formation, which is an ultra-tight, multimineral, low-resistivity reservoir. This study presents a workflow for Sw prediction using well logs, core data, and ML algorithms. Logs and core data were gathered from 29 wells drilled in the Bakken Formation. Due to the inaccuracy and lack of robustness of the tried and tested regression models (e.g., linear regression, random forest regression) in predicting Sw as a continuous variable, the problem was reformulated as a classification task. Instead of exact values, the Sw predictions were made in intervals of 10% increments representing 10 classes from 0% to 100%. Gradient boosting and random forest classifiers scored the best classification accuracy, and these two models were used to construct a voting classifier that achieved the best accuracy of 85.53%. The ML model achieved much better accuracy than conventional resistivity-based methods. By conducting this study, we aim to develop a new workflow to improve the prediction of Sw in reservoirs where conventional methods have poor performance. Full article

(This article belongs to the Special Issue GeoEnergy Science and Engineering)

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28 pages, 6761 KiB

Open AccessArticle

Prediction of Key Parameters in the Design of CO₂ Miscible Injection via the Application of Machine Learning Algorithms

by Mohamed Hamadi, Tayeb El Mehadji, Aimen Laalam, Noureddine Zeraibi, Olusegun Stanley Tomomewo, Habib Ouadi and Abdesselem Dehdouh

Eng 2023, 4(3), 1905-1932; https://doi.org/10.3390/eng4030108 - 07 Jul 2023

Cited by 4 | Viewed by 1891

Abstract

The accurate determination of key parameters, including the CO₂-hydrocarbon solubility ratio (Rs), interfacial tension (IFT), and minimum miscibility pressure (MMP), is vital for the success of CO₂-enhanced oil recovery (CO₂-EOR) projects. This study presents a robust machine [...] Read more.

The accurate determination of key parameters, including the CO₂-hydrocarbon solubility ratio (Rs), interfacial tension (IFT), and minimum miscibility pressure (MMP), is vital for the success of CO₂-enhanced oil recovery (CO₂-EOR) projects. This study presents a robust machine learning framework that leverages deep neural networks (MLP-Adam), support vector regression (SVR-RBF) and extreme gradient boosting (XGBoost) algorithms to obtained accurate predictions of these critical parameters. The models are developed and validated using a comprehensive database compiled from previously published studies. Additionally, an in-depth analysis of various factors influencing the Rs, IFT, and MMP is conducted to enhance our understanding of their impacts. Compared to existing correlations and alternative machine learning models, our proposed framework not only exhibits lower calculation errors but also provides enhanced insights into the relationships among the influencing factors. The performance evaluation of the models using statistical indicators revealed impressive coefficients of determination of unseen data (0.9807 for dead oil solubility, 0.9835 for live oil solubility, 0.9931 for CO₂-n-Alkane interfacial tension, and 0.9648 for minimum miscibility pressure). One notable advantage of our models is their ability to predict values while accommodating a wide range of inputs swiftly and accurately beyond the limitations of common correlations. The dataset employed in our study encompasses diverse data, spanning from heptane (C₇) to eicosane (C₂₀) in the IFT dataset, and MMP values ranging from 870 psi to 5500 psi, covering the entire application range of CO₂-EOR. This innovative and robust approach presents a powerful tool for predicting crucial parameters in CO₂-EOR projects, delivering superior accuracy, speed, and data diversity compared to those of the existing methods. Full article

(This article belongs to the Special Issue GeoEnergy Science and Engineering)

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14 pages, 6576 KiB

Open AccessArticle

The Development and Validation of Correlation Charts to Predict the Undisturbed Ground Temperature of Pakistan: A Step towards Potential Geothermal Energy Exploration

by Tabish Ali, Waseem Haider, Muhammad Haziq, Muhammad Omar Khan and Arif Hussain

Eng 2023, 4(3), 1837-1850; https://doi.org/10.3390/eng4030104 - 30 Jun 2023

Cited by 1 | Viewed by 1055

Abstract

As a country, Pakistan is mostly dependent on fossil fuels for fulfilling its energy demand, which is expensive, as well as being environmentally unfriendly. It is high time that the country decides to shift from fossil fuels to renewable energy resources like geothermal, [...] Read more.

As a country, Pakistan is mostly dependent on fossil fuels for fulfilling its energy demand, which is expensive, as well as being environmentally unfriendly. It is high time that the country decides to shift from fossil fuels to renewable energy resources like geothermal, wind, solar, etc., to cater for global warming issues. Pakistan has a lot of potential geothermal sites, as the location of Pakistan lies on several fault lines and hot springs, thus making it very easy to extract the temperature from deep inside the earth and harness it for Geothermal Energy. Also, a sound knowledge of ground temperature is essential to use geothermal energy, which is obtained by drilling boreholes and putting in sensors. However it becomes a very expensive and labor intensive procedure. Therefore, to avoid the huge cost for drilling boreholes, particularly for ground temperature analysis, a numerical approach has been considered for determining ground temperature. Furthermore, correlation charts between air and ground temperatures have been developed, as there were no proper studies on the ground temperature of Pakistan. Then, with the help of a boreholes drilled in the National University of Sciences and Technology, Islamabad, Pakistan, the actual ground and numerically calculated temperatures have been compared. The results show a temperature error margin in the range between 0.27% for higher depths of about 5.6 m and 7.3% near the surface of about 2.7 m. Thus, it is shown that the proposed method is easy to implement and better than large scale testing methods for the depths at which geothermal energy is extracted. Full article

(This article belongs to the Special Issue GeoEnergy Science and Engineering)

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16 pages, 4568 KiB

Open AccessArticle

Offset Well Design Optimization Using a Surrogate Model and Metaheuristic Algorithms: A Bakken Case Study

by Ahmed Merzoug and Vamegh Rasouli

Eng 2023, 4(2), 1290-1305; https://doi.org/10.3390/eng4020075 - 23 Apr 2023

Cited by 3 | Viewed by 1796

Abstract

Fracture-driven interaction FDI (colloquially called “Frac-hit”) is the interference of fractures between two or more wells. This interference can have a significant impact on well production, depending on the unconventional play of interest (which can be positive or negative). In this work, the [...] Read more.

Fracture-driven interaction FDI (colloquially called “Frac-hit”) is the interference of fractures between two or more wells. This interference can have a significant impact on well production, depending on the unconventional play of interest (which can be positive or negative). In this work, the surrogate model was used along with metaheuristic optimization algorithms to optimize the completion design for a case study in the Bakken. A numerical model was built in a physics-based simulator that combines hydraulic fracturing, geomechanics, and reservoir numerical modeling as a continuous simulation. The stress was estimated using the anisotropic extended Eaton method. The fractures were calibrated using Microseismic Depletion Delineation (MDD) and microseismic events. The reservoir model was calibrated to 10 years of production data and bottom hole pressure by adjusting relative permeability curves. The stress changes due to depletion were calibrated using recorded pressure data from MDD and FDI. Once the model was calibrated, sensitivity analysis was run on the injected volumes, the number of clusters, the spacing between clusters, and the spacing between wells using Sobol and Latin Hypercube sampling. The results were used to build a surrogate model using an artificial neural network. The coefficient of correlation was in the order of 0.96 for both training and testing. The surrogate model was used to construct a net present value model for the whole system, which was then optimized using the Grey Wolf algorithm and the Particle Swarm Optimization algorithm, and the optimum design was reported. The optimum design is a combination of wider well spacing (1320 ft), tighter cluster spacing (22 ft), high injection volume (1950 STB/cluster), and a low cluster number per stage (seven clusters). This study suggests an optimum design for a horizontal well in the Bakken drilled next to a well that has been producing for ten years. The design can be deployed in new wells that are drilled next to depleted wells to optimize the system’s oil production. Full article

(This article belongs to the Special Issue GeoEnergy Science and Engineering)

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13 pages, 4845 KiB

Open AccessFeature PaperArticle

Aperture Design Optimization of Wire-Wrapped Screens for SAGD Production Wells

by Jesus David Montero Pallares, Chenxi Wang, Mohammad Haftani and Alireza Nouri

Eng 2023, 4(2), 1058-1070; https://doi.org/10.3390/eng4020062 - 06 Apr 2023

Viewed by 1612

Abstract

Wire-wrapped screens have been established as one of the primary sand control devices in Steam-Assisted Gravity Drainage (SAGD) wells due to the high open-to-flow area and superior plugging attributes. However, their design is still a point of interest for thermal operations. Generally, existing [...] Read more.

Wire-wrapped screens have been established as one of the primary sand control devices in Steam-Assisted Gravity Drainage (SAGD) wells due to the high open-to-flow area and superior plugging attributes. However, their design is still a point of interest for thermal operations. Generally, existing approaches rely on one or more particular points of reservoir sands’ particle size distribution (PSD) and rules of thumb inferred from other devices like the slotted liners. This study used Sand Retention Testing (SRT) to analyze the performance of WWS under various testing conditions, which were neglected in the current design criteria. The experimental investigation leads to a set of graphical design criteria that provide an optimum aperture size window. The results show that the sand retention performance of WWS is highly dependent on the flow velocities of the wetting phase. Moreover, the testing showed satisfactory plugging performance of WWS even with narrow aperture sizes, proving a superior performance for low-quality oil sands. Full article

(This article belongs to the Special Issue GeoEnergy Science and Engineering)

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16 pages, 6212 KiB

Open AccessFeature PaperArticle

Reservoir Adaptability Evaluation and Application Technology of Carbon Quantum Dot Fluorescent Tracer

by Jinjian Chen, Jianxin Liu, Jijian Dai, Bo Lin, Chunyu Gao and Ci Wang

Eng 2023, 4(1), 703-718; https://doi.org/10.3390/eng4010042 - 22 Feb 2023

Viewed by 1668

Abstract

This study investigates the application of carbon quantum dots as tracers in inter-well connectivity monitoring. A new laboratory-made water-soluble carbon quantum dot fluorescent tracer (CQD-W) was studied using 3D fluorescence characterization, structural characterization, reservoir suitability evaluation, and core flow experiments. The experimental results [...] Read more.

This study investigates the application of carbon quantum dots as tracers in inter-well connectivity monitoring. A new laboratory-made water-soluble carbon quantum dot fluorescent tracer (CQD-W) was studied using 3D fluorescence characterization, structural characterization, reservoir suitability evaluation, and core flow experiments. The experimental results showed that CQD-W has a size of about 2 nm, a minimum detection limit of 10⁻² mg·L⁻¹. It has good stability when the salinity is 200,000 mg·L⁻¹, the concentration of Ca²⁺ is 1000 mg·L⁻¹, the pH value is 1–9, and the temperature is 80 °C. Because CQD-W contains many functional groups, such as carboxyl and hydroxyl, it shows good water solubility and has a negative surface charge. In the process of formation flow, CQD-W has a small adsorption amount, high tracer resolution, and excellent injectivity and mobility, meaning it is less likely to cause reservoir damage. Through the study of this method, the application field of carbon quantum dots is broadened, and it is proved that the CQD-W fluorescent tracer has a high potential for application in the oil industry, laying the foundation for the popularization of this technology. Full article

(This article belongs to the Special Issue GeoEnergy Science and Engineering)

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16 pages, 4230 KiB

Open AccessArticle

Exploring Neogene Marine Diatomites in Western Crete: A New Source-Rock Candidate with Hydrocarbon Generation Potential?

by Dimosthenis Telemenis, Vagia-Ioanna Makri, Emmanouil Manoutsoglou and Spyridon Bellas

Eng 2023, 4(1), 285-300; https://doi.org/10.3390/eng4010017 - 18 Jan 2023

Cited by 1 | Viewed by 1773

Abstract

Diatomites are sedimentary rocks rich in siliceous algae, mainly diatoms, and are evident in Greece mainly in Neogene successions. Despite their significance and worldwide potential as source rocks for hydrocarbons, little is known about them in the wider area of Greece, limited in [...] Read more.

Diatomites are sedimentary rocks rich in siliceous algae, mainly diatoms, and are evident in Greece mainly in Neogene successions. Despite their significance and worldwide potential as source rocks for hydrocarbons, little is known about them in the wider area of Greece, limited in their biostratigraphic characteristics and industrial use. This study assesses for the first time the Neogene diatomites in Western Crete and focuses on their source rock quality and hydrocarbon generation potential on top of their stratigraphic characteristics. The studied synthetic outcrop is of the Miocene age and is located in the Apokoronas sedimentary basin, in the Chania province. It is subdivided into four subsections reaching heights of 13 m. It has a total documented, visible extend of 90–100 m and presents adequate thickness in relation to other reported diatomitic occurrences in Crete. A SEM study and bulk sampling of 28 samples has been carried out on this outcrop and geochemical analysis has been conducted by means of a Rock-Eval 6 pyrolysis to facilitate the understanding of hydrocarbon potential. Stratigraphic analysis supports the establishment of system tracts (ST), with transgressive ones (TST) illustrated by fining-upward sequences including highstands (HST). At the top, a final coarsening-upwards sequence suggests a regressive sequence (RST) most probably related to the Messinian Salinity Crisis (MSC) event. Total organic carbon (TOC, %wt.) values are found to reach 3.4% in the diatomites, while siltstone/mudstone interlayers encounter lower TOC (%wt.), yet with exceptions reaching TOC levels as high as the diatomaceous facies. Overall, Rock-Eval pyrolysis shows that organic matter from the studied cross sections is immature with the hydrocarbon generation potential ranging from poor to excellent. The kerogen type is proved to be type III with poor to almost good quality. This suggests the presence of a prolific diatomaceous source rock in Western Crete demonstrating a high significance for the offshore hydrocarbon exploration in the Eastern Mediterranean that could potentially be related to the offshore Western and Southern Crete E&P-awarded blocks. Full article

(This article belongs to the Special Issue GeoEnergy Science and Engineering)

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23 pages, 7939 KiB

Open AccessFeature PaperArticle

Geomechanical Feasibility Analysis of Salt Cavern Gas Storage Construction in Sanshui Basin, Guangdong Province

by Haitao Li, Qiqi Wanyan, Guosheng Ding, Kang Li, Yanxia Kou, Song Bai, Lina Ran, Jianan Wu and Jingen Deng

Eng 2022, 3(4), 709-731; https://doi.org/10.3390/eng3040048 - 16 Dec 2022

Cited by 2 | Viewed by 2204

Abstract

Salt cavern gas storage has become the key project of current and future underground gas storage (UGS) facilities construction due to their efficient peak-shaving and supply assurance capacities. The Sanshui Basin in Guangdong Province, China, is rich in salt resources and has high-purity [...] Read more.

Salt cavern gas storage has become the key project of current and future underground gas storage (UGS) facilities construction due to their efficient peak-shaving and supply assurance capacities. The Sanshui Basin in Guangdong Province, China, is rich in salt resources and has high-purity salt rock, which is a potential area for the construction of salt cavern underground gas storage. To speed up the large-scale construction of underground gas storage in China and promote the sustainable development of the natural gas market, it is very necessary to analyze the geomechanics of the target salt layer and study the feasibility of gas storage construction. Based on comprehensive experiments of rock mechanics and thermodynamics, the strength, creep and temperature-sensitive mechanical properties of the target rock in Sanshui Basin were studied. Then, according to the geological conditions of Sanshui salt formation, a three-dimensional geological model was established to analyze the stability of salt cavern gas storage under the injection-production operation. The results show that the average tensile strength and uniaxial compressive strength of salt rock are 1.51 MPa and 26.04 MPa, respectively, showing lower strength. However, under triaxial compression, the compressive strength of salt rock increases significantly, and there is no obvious shear failure phenomenon observed. Moreover, after the peak strength, the salt rock still has a large bearing capacity. In addition, under the confining pressure of 30 MPa, the strength of salt rock decreases by 8.3% at a temperature of 60 °C compared with that at room temperature, indicating that the temperature has a low, modest effect on the mechanical properties of salt rock. The stability analysis shows that, under an injection-production operating pressure of 10–23 MPa, the displacement, plastic zone range and volume convergence rate of single cavity and cavity group are small, and the cavity shows good stability. Overall, the target salt formation in Sanshui Basin, Guangdong Province, presents a good geomechanical condition suitable for the construction of underground salt cavern gas storage. This study can provide a reference for the development and design of salt cavern UGS. Full article

(This article belongs to the Special Issue GeoEnergy Science and Engineering)

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Review

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19 pages, 2229 KiB

Open AccessReview

A Review of the Metallogenic Mechanisms of Sandstone-Type Uranium Deposits in Hydrocarbon-Bearing Basins in China

by Guihe Li, Jia Yao, Yiming Song, Jieyun Tang, Hongdou Han and Xiangdong Cui

Eng 2023, 4(2), 1723-1741; https://doi.org/10.3390/eng4020098 - 19 Jun 2023

Cited by 2 | Viewed by 1300

Abstract

As a valuable mineral resource, uranium is extensively utilized in nuclear power generation, radiation therapy, isotope labeling, and tracing. In order to achieve energy structure diversification, reduce dependence on traditional fossil fuels, and promote the sustainable development of energy production and consumption, research [...] Read more.

As a valuable mineral resource, uranium is extensively utilized in nuclear power generation, radiation therapy, isotope labeling, and tracing. In order to achieve energy structure diversification, reduce dependence on traditional fossil fuels, and promote the sustainable development of energy production and consumption, research on the metallogenic mechanisms and related development technologies of uranium resources has been one of the focuses of China’s energy development. Sandstone-type uranium deposits make up approximately 43% of all deposits in China, making them the most prevalent form of uranium deposit there. Sandstone-type uranium deposits and hydrocarbon resources frequently coexist in the same basin in China. Therefore, this study summarizes the spatial and chronological distribution, as well as the geological characteristics, of typical sandstone-type uranium deposits in China’s hydrocarbon-bearing basins. From the perspectives of fluid action, geological structure, and sedimentary environment, the metallogenic mechanisms of sandstone-type uranium deposits in hydrocarbon-bearing basins are explored. According to the research, the rapid reduction effect of oil and gas in the same basin is a major factor in the generation of relatively large uranium deposits. Additionally, ions such as CO₃²⁻ and HCO₃⁻ in hydrothermal fluids of hydrocarbon-bearing basins, which typically originate from dispersed oil and gas, are more conducive to uranium enrichment and sedimentation. This study provides guidance for efficient sandstone-type uranium deposit exploration and production in hydrocarbon-bearing basins and helps to achieve significant improvements in uranium resource exploitation efficiency. Full article

(This article belongs to the Special Issue GeoEnergy Science and Engineering)

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27 pages, 1441 KiB

Open AccessFeature PaperReview

Carbon Capture Utilisation and Storage in Extractive Industries for Methanol Production

by Antonis Peppas, Sotiris Kottaridis, Chrysa Politi and Panagiotis M. Angelopoulos

Eng 2023, 4(1), 480-506; https://doi.org/10.3390/eng4010029 - 01 Feb 2023

Cited by 1 | Viewed by 5326

Abstract

The elevated increase of CO₂ emissions related to activities of the extractive industry is becoming a challenging issue gradually affecting climate change and global warming. In this frame, the effective utilisation of CO₂ through the techniques of Carbon Capture and Storage [...] Read more.

The elevated increase of CO₂ emissions related to activities of the extractive industry is becoming a challenging issue gradually affecting climate change and global warming. In this frame, the effective utilisation of CO₂ through the techniques of Carbon Capture and Storage (CCS) as well as Carbon Capture and Utilisation (CCU) can alleviate the greenhouse effect. Converting CO₂ into a value-added chemical or liquid fuel (e.g., methanol, hydrocarbons, propylene, dimethyl ether, ethylene, etc.) is a promising approach in this regard. Methanol (MeOH) synthesis offers a key feedstock for industries, being both an industrial commodity for several chemical products and an efficient transportation fuel. This article presents a review of the CCS and CCU technologies for the production of MeOH in extractive industries. The CCS technologies investigated in this framework are the amine-based absorption and the WGS-enhanced CCS. The CCU technologies are CO₂ hydrogenation and enhanced CO₂ transformation by the Fischer-Tropsch reaction. Incorporating these systems for the processing of the flue-gases of the extractive industries significantly reduces the CO₂ emissions, while creating new revenues by the production of valuable MeOH. Full article

(This article belongs to the Special Issue GeoEnergy Science and Engineering)

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32 pages, 7516 KiB

Open AccessFeature PaperReview

DFN: An Emerging Tool for Stochastic Modelling and Geomechanical Design

by Peter Kolapo, Nafiu Olanrewaju Ogunsola, Prosper Munemo, Damilola Alewi, Kayode Komolafe and Ahmid Giwa-Bioku

Eng 2023, 4(1), 174-205; https://doi.org/10.3390/eng4010011 - 05 Jan 2023

Cited by 4 | Viewed by 3208

Abstract

The discrete fracture networks (DFN) have become indispensable tools for geomechanical modelling of jointed rock masses. The technology creates a three-dimensional (3D) representation of fracture geometry used in the construction of surface and subsurface engineering projects in mining, civil engineering, and fracturing of [...] Read more.

The discrete fracture networks (DFN) have become indispensable tools for geomechanical modelling of jointed rock masses. The technology creates a three-dimensional (3D) representation of fracture geometry used in the construction of surface and subsurface engineering projects in mining, civil engineering, and fracturing of the reservoir in the oil and gas industry. The approach depends on the accuracy of the data obtained during site investigation to create models that represent the fracture geometry of the structure. The better the acquired information available, the better the stochastic analysis that determines the engineering applications and designs that can be carried out. Therefore, it is important to use instruments that can capture fracture distribution characteristics such as fracture intensity, fracture orientation, spatial distribution, fracture length, fracture aperture, and size. This study provides a detailed review of the recent advances in the application of a DFN for modelling jointed rock masses in different engineering applications. The paper shows the principles of modelling in a DFN, including various data-capturing methodologies, and the general application of DFN in various fields. Several case studies where the DFN method was applied are presented in the paper. These include evaluation of slope in an open pit mine, modelling of discontinuity in tunneling, stability evaluation of coal seam longwall, the design of high-level radioactive waste, prediction of groundwater flow, fracturing of petroleum reservoirs, and geothermal cracking of shale gas in the coal bed. However, despite the versatility of the DFN technique, there are still some limitations and challenges to the integration of complexities encountered in rock masses within DFN models. Full article

(This article belongs to the Special Issue GeoEnergy Science and Engineering)

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