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Papers by Zohreh Movahed
International Journal of Applied Sciences & Development, Nov 27, 2023
International Journal of Chemical Engineering and Materials, Nov 26, 2023
EARTH SCIENCES AND HUMAN CONSTRUCTIONS, Dec 13, 2023
In this work, the process that the bedding dip and strike can be calculated using image logs will... more In this work, the process that the bedding dip and strike can be calculated using image logs will be explained by using a unique case study and a number of valuable image log interpretation examples. This job will be done in Gachsaran field, one of the most important Iranian fields, and the main reservoir that will be studied is Asmari reservoir, one of the most important Iranian oil and gas reservoirs.
By interpreting image logs, both the directions of drilling induced fractures parallel to the max... more By interpreting image logs, both the directions of drilling induced fractures parallel to the maximum horizontal in-situ stress direction and borehole breakouts parallel to the minimum horizontal in-situ stress direction can be calculated. In this work, 10 wells located in Gachsaran field were selected then the direction of drilling induced fractures and borehole breakouts in these wells was examined by using image logs and other geological log interpretation. This work was done in order to have a better understanding of structural geology in this field and also explain the methodology by showing the selected log interpretation examples from this field.
International Journal of Applied Sci, 2023
The Khalij limestone member, well-known for its abundant benthic facies, is situated in the middl... more The Khalij limestone member, well-known for its abundant benthic facies, is situated in the middle segment of the Gadvan shaly formation, boasting an average thickness of approximately 14 meters. This specific member is exclusively found below the surface, devoid of any exposed outcrops, and is characterized by the presence of easily identifiable orbitolinid limestone. Well logging techniques, such as Gamma Ray and Density measurements, prove particularly effective in identifying this distinct layer. The primary objective of this study was to conduct a comprehensive analysis of the lithostratigraphy and microstratigraphy within the Gadvan formation, with a specific emphasis on the Khalij limestone member. A regional stratigraphic assessment covered an extensive area of about 100,000 square kilometers in the Fars and Dezful regions within the Zagros region. To achieve this, data from 38 exploration and development wells were utilized, and approximately 1,400 microscopic thin sections from the Gadvan formation were meticulously examined. The paramount contribution of this research lies in the establishment of a representative type section for the Khalij limestone member, characterized by a thickness of 13 meters. Detailed microscopic analysis has revealed that this member predominantly comprises wackestone carbonate, featuring microfossils, particularly foraminifera from the orbitolindae family. Based on the observed species index, it has been determined to be of Barremian age and linked to a lagoon-like depositional environment.
https://www.akademiabaru.com/doc/ARAMV3\_N1\_P1\_8.pdf, 2014
https://www.akademiabaru.com/doc/ARAMV3\_N1\_P1\_8.pdf Image log technology is an advanced technolo... more https://www.akademiabaru.com/doc/ARAMV3_N1_P1_8.pdf
Image log technology is an advanced technology that helps us in finding the location, dip, azimuth, strike and type of faults in any science related to geology. Finding out this information from image logs is not so easy, and many geologists are looking for an industrial source with real examples of log interpretation to have a better understanding of this technology. Therefore, in this study, a unique case study and a number of valuable log interpretation examples were used, and the process was explained completely. This job was done in Gachsaran field, one of the most important Iranian fields, and the main reservoir is Asmari reservoir, one of the most important Iranian oil and gas reservoirs. A unique educational paper is produced from this study, which can be useful for other geologists who are interested in fault interpretation and image log technology.
Journal of Applied Sciences 23(1):34-46, 2023
Characterizing fracture properties in naturally fractured reservoirs poses a significant challeng... more Characterizing fracture properties in naturally fractured reservoirs poses a significant challenge. While well-testing remains valuable, it often fails to provide precise descriptions of these properties. Bridging this gap requires the integration of geological expertise to enhance fracture assessment. This study addresses the limitations of well-test analysis and explores the application of Conventional Image Logs in structural, fracture, and geomechanical analysis. However, effectively combining these applications with well-test analysis on a field scale reveals a substantial knowledge gap. A critical challenge in this context is the absence of a defined procedure for calculating the variable "σ," a crucial parameter for simulating fractured carbonate reservoirs using image log fracture density. Integrating geological knowledge is essential to reduce uncertainties associated with well-test analysis and provide more accurate characterizations of fracture properties. Image log data processing emerges as a valuable avenue for gaining insights into the static attributes of naturally fractured reservoirs. This study focuses on Characterizing fractures using data from ten image logs and Developing a more accurate simulation model through the interpretation of images, with a particular emphasis on OBM imaging. The main goals of this fracture study revolve around establishing correlations between fracture densities well by well within the simulation and enhancing the accuracy of the simulation model by incorporating fracture data from image logs. Borehole imaging tools such as FMI/FMS and OBMI-UBI play a pivotal role in identifying significant structural features, including faults, fractures, and bedding. Fine-tuning fracture parameters during the history matching process, while potentially time-consuming, significantly impacts other historical match parameters. Consequently, the reliability of reservoir simulation results, predictions, and recovery enhancement strategies hinges on the precision of fracture properties and their distribution within the model. Recent advances in interpretation techniques have expanded the horizons of image interpretation, enabling the creation of more accurate simulation models for fractured reservoirs using fracture data obtained from image logs. The overarching goal of this project is to comprehensively evaluate a fractured reservoir field by integrating data from ten individual wells. Keywords: Well-testing, fracture evaluation, Image log data, fracture density, simulation sensitivity analysis.
https://asb.scione.com/cms/abstract.php?id=273 , 2024
https://asb.scione.com/cms/abstract.php?id=273 Background and Objective: The Asmari Formation p... more https://asb.scione.com/cms/abstract.php?id=273
Background and Objective: The Asmari Formation presents substantial challenges in reservoir management due to its structural complexities. Traditional core sampling methods fall short of accurately characterizing the fractured regions, impacting the efficacy of reservoir exploitation. Current study aims to enhance the understanding of the Asmari reservoir's structural and fracture complexities to improve well-test analyses and establish a detailed structural model for fracture characterization. Materials and Methods: The Formation Micro Imager (FMI) and geological logs utilized in well ZE-15, located within the Asmari Formation, for our experimental design. The FMI data, collected between depths of 4374 and 4640 m, was instrumental in assessing structural dips and mapping natural fractures. This approach facilitated a comprehensive analysis of fracture properties and structural orientation, incorporating statistical analyses to interpret the data accurately. Results: The FMI logging revealed a consistent structural dip of 33 degrees towards S62W across the Asmari Formation. Three main fracture zones were identified at depths of 4377-4459 m (Zone 1), 4459-4480 m (Zone 2) and 4480-4574 m (Zone 3), displaying a predominant WNW-ESE strike direction. This orientation correlates with the Zeloi structure's longitudinal alignment and the bedding strike. Further, elliptical borehole shapes observed in FMI images and caliper readings suggested the direction of minimum and maximum horizontal stresses, providing insights into the stress orientations affecting the formation. Conclusion: The current study successfully delineated the structural and fracture complexities within the Asmari reservoir, offering crucial insights into its stress orientations and natural fracture systems. This enhanced understanding is vital for optimizing reservoir exploitation strategies and improving recovery rates from this challenging geological formation.
https://asb.scione.com/cms/abstract.php?id=272, 2024
https://asb.scione.com/cms/abstract.php?id=272 Background and Objective: Accessing the Asmari re... more https://asb.scione.com/cms/abstract.php?id=272
Background and Objective: Accessing the Asmari reservoir poses challenges due to its complex structure, affecting well-test analysis accuracy in delineating fracture properties. Traditional core sampling struggles in highly fractured regions, leading to low recovery rates in unfavorable reservoir sections. The main objective of this study is to explore the challenges of accurately characterizing the fracture properties of the Asmari reservoir due to its structural complexities. Specifically, it aims to assess the effectiveness of using advanced borehole imaging tools, namely Oil-Based Mud Imager (OBMI) and Ultrasonic Borehole Imager (UBI), as alternatives to traditional core sampling and well-testing methods. Materials and Methods: Well GS-325 utilized OBMI and UBI tools to explore the Asmari Formation. The study involved a meticulous examination of geological features and structural attributes to understand the factors contributing to the observed thickness. Interpretation included manual dip picking using sinusoid techniques, followed by the classification of dips into bed boundaries and fractures. Results: The investigation revealed geological variations affecting the expected thickness of the Asmari Formation, enhancing comprehension of its complexities. The study identified 517 fractures within the Asmari interval, elucidating structural intricacies within the reservoir. Conclusion: The study demonstrates the successful use of OBMI/UBI imaging tools for identifying fractures and structural details in the Asmari Formation, despite challenges in shifting from oil-based to water-based drilling fluids. KEYWORDS Oil based mud micro-imager tool, ultrasonic borehole imager tool, fracture, structural dip, bedding, structural complexity
https://asb.scione.com/cms/abstract.php?id=271, 2024
https://asb.scione.com/cms/abstract.php?id=271 Background and Objective: Exploration of carbon... more https://asb.scione.com/cms/abstract.php?id=271
Background and Objective: Exploration of carbonate reservoirs in structurally complex areas, particularly those overlain by extensive evaporate formations, poses significant challenges in structural delineation. Lack of adequate structural geology information, especially in naturally fractured reservoirs, hampers drilling operations. In Iran, insufficient data on fractured reservoirs have hindered drilling activities. This study aims to assess the impact of limited structural information on drilling operations in complex naturally fractured reservoirs and underscores the efficacy of borehole imaging tools in addressing these challenges. The primary objective is to establish a precise structural model for the Asmari reservoir in the Gachsaran field. Materials and Methods: Utilizing well site geologist reports and formation cuttings analysis, this research examines drilling challenges encountered in penetrating the lower Asmari reservoir. Oil-Based Mud Micro Imager-Ultrasonic Borehole Imager (OBMI-UBI) tools were deployed in the interval from 2117 to 2772 m to investigate discrepancies in predicted reservoir depths. Results: The analysis revealed a deviation in the well trajectory, with an initial northeast (NE) direction shifting gradually to southwest (SW) until reaching total depth (TD). Caprock and bedding dips plotted alongside the trajectory unveiled parallelism with the middle Asmari layers, indicating the need for a directional change to exit the reservoir successfully. Borehole imaging played a pivotal role in delineating structural complexities, providing crucial insights for the effective positioning of wells. Conclusion: Insufficient structural data in complex carbonate reservoirs pose significant challenges to drilling operations. However, the deployment of borehole imaging tools, as demonstrated in this study, enables precise structural modeling and enhances drilling efficiency in such environments.
International Conference on Mathematical and Computational Methods in Science and Engineering, 2015
Application of artificial neural networks in fracture characterization and modeling technology A... more Application of artificial neural networks in fracture characterization and modeling technology
Alizadeh, Mostafa and Junin, Radzuan and Mohsin, Rahmat and Movahed, Zohreh and Alizadeh, Mehdi and Alizadeh, Mohsen (2015) Application of artificial neural networks in fracture characterization and modeling technology. In: 17th International Conference on Mathematical and Computational Methods in Science and Engineering (MACMESE '15), 23-25 April, 2015, Kuala Lumpur, Malaysia.
Full text not available from this repository.
Official URL: http://www.wseas.us/e-library/conferences/2015/Mal...
Abstract
Fracture characterization and modeling technology can characterize the fractures of naturally fractured reservoirs. In this work, a novel application of Artificial Neural Networks (ANNs) will be introduced which can be used to improve this technology. The new technique by using the feed-forward ANN with backpropagation learning rule can predict the fractures dip inclination degree of the third well using the data from the other two wells nearby. The result obtained showed that the ANNs model can simulate the relationship between fractures dips in these three wells which the multiple R of training and test sets for the ANN model are 0.95099 and 0.912197, respectively.
Item Type: Conference or Workshop Item (Paper)
Uncontrolled Keywords: neural networks, technology
Subjects: T Technology > TP Chemical technology
Divisions: Petroleum and Renewable Energy Engineering
ID Code: 60765
Deposited By: Fazli Masari
Deposited On: 28 Feb 2017 01:38
Last Modified: 02 Aug 2017 08:13
Arabian Journal of Geosciences, Mar 1, 2016
Movahed, Z., Junin, R., Amiri Bakhtiary, H., Taghavi Poor, S., Mohamadian, R. (2016). The evaluat... more Movahed, Z., Junin, R., Amiri Bakhtiary, H., Taghavi Poor, S., Mohamadian, R. (2016). The evaluation of borehole imaging result comparing with cores in Sarvak fractured and non- fractured reservoir, Arabian journal of Geosciences. https://link.springer.com/article/10.1007/s12517-015-2091-1
Abstract
Core samples are still today considered as the standard measurement against all other measurements which must be compared. Core analysis usually focuses on the worse portion of the reservoir due to the fact that core recovery has rarely been well in a highly fractured zone; hence, permeability measured from core sample is often not representative. Core analysis is a common method to identify small-scale fractures of the well and permeability and porosity; however, there are some limitations in the core procedure such as it is highly expensive and unidirectional and has a low recovery coefficient in fractured zone. In contrast, there tends to be a mistrust and even a suspicion of those logging instruments that make measurements which threaten to replicate or even replace the “sacred core.” Thus, image logs are more useful to study the subsurface fractures in these such cases and the logs which come closest to achieving this are the high-resolution micro resistivity (OBMI) and acoustic geological imaging (UBI). The core and OBMI-UBI result was matched in order to verify the log measurements. Furthermore, FMI data were integrated with other open-hole logs to derive a permeability curve. As demonstrated in the case studies, it is believed that the permeability in the basement could be reasonably evaluated using this method. As a result, this exercise has proven to be very valuable, not only for demonstrating the value of the log data, but also it has also highlighted some significant limitations of the core in water-based mud and oil-based mud systems.
Journal of African Earth Sciences
Integrating hydraulic flow unit concept and adaptive neuro-fuzzy inference system to accurately e... more Integrating hydraulic flow unit concept and adaptive neuro-fuzzy inference system to accurately estimate permeability in heterogeneous reservoirs: Case study Sif Fatima oilfield, southern Algeria
Author links open overlay panelFaycal Djebbas a, Ouafi Ameur-Zaimeche a, Rabah Kechiched a, Salim Heddam b, David A. Wood c, Zohreh Movahed e
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https://doi.org/10.1016/j.jafrearsci.2023.105027
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Abstract
Formation characteristics are a crucial requirement for reservoir modeling and they need to be constantly updated as new static and/or dynamic reservoir-property details become available. This improves reservoir interpretation while achieving a good history-matching for a better representation of the reservoir. This paper proposes a new method to estimate reservoir permeability in an oil-producing reservoir by applying two distinct cases: partially cored and completely non-cored wellbores. The approach involves the determination of hydraulic-flow units (HFU) using a flow-zone indicator (FZI) distribution to consider the dynamic aspect of the permeability, which strongly influences fluid flow through porous media. The FZI is clustered by normal probability analysis to identify the optimum number of HFU clusters. The estimated reservoir permeability is validated in static and dynamic reservoir models. For an accurate prediction of the FZI over the entire reservoir thickness, an adaptive-neuro-fuzzy-inference system (ANFIS) is developed using conventional well-log variables: (i) gamma-ray (GR), (ii) sonic (DT), (iii) density (RHOB), (iv) deep resistivity (DLL), and (iv) neutron porosity (NPHI) calibrated with the available core data. The static regression parameters root-mean-squared error (RMSE), mean absolute error (MAE), coefficient of determination (R2), and R2adjusted are used to evaluate the performance of the ANFIS model in predicting FZI to determine HFU for estimating reservoir permeability. To validate this approach, a matching quality check of the downhole and reservoir pressure is carried out using a dynamic reservoir simulation model. Historical data collected from wellbore OPW-1 drilled in the Sif Fatima oilfield (Algeria) are used to evaluate the accuracy of the proposed permeability-prediction framework. The ANFIS model can accurately and efficiently predict the FZI exhibiting R2, R2adjusted, RMSE, and MAE of approximately (≈0.981, ≈0.979, ≈0.014, ≈4,600E-08)), (≈0.933, ≈0.891, ≈0.032, ≈1.615E-03), and (≈0.970, ≈0.968, ≈0.018, ≈2.381E-04)) for the training, testing and complete dataset, respectively. When applied to predict reservoir permeability, the Hydraulic Flow Unit concept was able to generate accurate results from the predicted FZI data by applying the modified Kozeny-Carman equation with, R2, RMSE and MAE values of approximately ≈0.9702, ≈0.969, ≈9.604, and ≈4.398, respectively. The calculated permeability was validated successfully at well and field levels. Additionally, it generated more accurate history matches of the well and the reservoir pressure trends than the previous permeability model, and consequently improved the reservoir modelling workflow.
Current Research in Geoscience, 2022
Analytical Fractured Reservoir Characterization by using Geological and Petrophysical Logs Zohre... more Analytical Fractured Reservoir Characterization by using Geological and Petrophysical Logs
Zohreh Movahed1 and Farzaneh Aghajari2
1 Faculty of Petroleum and Renewable Energy Engineering, Springer, Karun Energy and Teleperformance, University Teknologi Malaysia - UTM, Malaysia
2 Department of Geology, National Industrial Cluster Program, Iran
Abstract
Due to structural complexities in some wells, higher than the expected thickness of the Asmari formation is found. Fracture intensity and deep-rooted fractures broadly increase the risk of unpredictable water production. The well-test analysis is not sufficient in describing fracture properties. Unfortunately, the core condition is poor in the fractured zones and cannot be used to provide reliable information. So, the objectives of this study are developing an accurate structural model for the Asmari reservoir, and fracture characterization in the borehole by interpreting image logs and comparing the log's image results with core data. Dip classification based on a geological log has the value of providing a direct demonstration of structural origin and detecting Asmari fault and fracture systems and their impact on production and answering structural issues. So, in this study, the borehole imaging tools were interpreted to find solutions for fracture systems and fracture attributes. Interpreting accurate structural dip determined the structural problem, thus bringing the precise location of the well within the Asmari reservoir. Fracture properties (open or closed), occurrence, orientation, spacing, and porosity were interpreted using an Image log. The high density of fractures seen on FMS image logs in the study well has been confirmed by inspection of the cores and the distinction between major and minor fracture types from the FMS image logs has been established following core review. As a result, this exercise has been confirmed to be very valuable, not only for indicating the value of the log data, but it has also emphasized some significant limitations of the core data. The amount of information extracted from the FMS image logs goes beyond that achieved from the core. This exercise has validated why image logs are the main source of fracture information in the oil fields of Iran.
Current Research in Geoscience
Volume 12 No. 1, 2022, 11-28
DOI: https://doi.org/10.3844/ajgsp.2022.11.28
Submitted On: 18 July 2022 Published On: 3 December 2022
How to Cite: Movahed, Z. & Aghajari, F. (2022). Analytical Fractured Reservoir Characterization by using Geological and Petrophysical Logs. Current Research in Geoscience, 12(1), 11-28. https://doi.org/10.3844/ajgsp.2022.11.28
Open AccessCopyright: © 2022 Zohreh Movahed and Farzaneh Aghajari. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Background and Objectives: Due to structural complexities in some wells, higher than the expected... more Background and Objectives: Due to structural complexities in some wells, higher than the expected thickness of Asmari formation is found. Fracture intensity and deep-rooted fractures broadly increase the risk of unpredictable water production. The well test analysis is not sufficient in describing fracture properties. Unfortunately, the core condition is poor in the fractured zones and cannot be used to provide reliable information. So, the objectives of this study are developing an accurate structural model for Asmari reservoir,fracture characterization in the borehole by interpreting image logs ,and comparing the log's image results with core data.Materials and Methods: Dip classification based on a geological log has the value of providing a direct demonstration of structural origin and detect Asmari fault and fracture systems and its impact on production and answer structural issue. So, in this study, the borehole imaging tools were interpreted to find solutions for fracture...
Environmental Science: an Indian journal, 2015
Structural analysis is the way to have a better understanding of structural geology in oil and ga... more Structural analysis is the way to have a better understanding of structural geology in oil and gas fields. By using the image log technology, we can do this analysis very well, but this process is complicated and it is still unknown to many researchers. Therefore, we decided to explain this process by using a unique case study and a number of valuableimage log interpretation examples. This jobwill be done in Gachsaran field, one of the most important Iranian fields, and the main reservoir that will be studied is Asmari reservoir, one of the most important Iranian oil and gas reservoirs. We aim to offer a unique educational paper that will be very useful for the other researchers who are interested in structural geology and image log technology. This job showed that the direction of bedding strike is almost NW-SE direction for theAsmari reservoir in the section of Gachsaran field.
Fractures provide the place for oil and gas to be reserved and they also can provide the pathway ... more Fractures provide the place for oil and gas to be reserved and they also can provide the pathway for them to move into the well, so having a proper knowledge of them is essential and every year the companies try to improve the existed softwares in this technology. In this work, the new technique is introduced to be added as a new application to the existed softwares such as Petrel and geoframe softwares. The data used in this work are image logs and the other geological logs data of tree wells located in Gachsaran field, wells number GS-A, GS-B and GS-C. The new technique by using the feed-forward artificial neural networks (ANN) with back-propagation learning rule can predict the fracture dip data of the third well using the data from the other 2 wells. The result obtained showed that the ANN model can simulate the relationship between fractures dips in these 3 wells which the multiple R of training and test sets for the ANN model is 0.95099 and 0.912197, respectively.
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International Journal of Applied Sciences & Development, Nov 27, 2023
International Journal of Chemical Engineering and Materials, Nov 26, 2023
EARTH SCIENCES AND HUMAN CONSTRUCTIONS, Dec 13, 2023
In this work, the process that the bedding dip and strike can be calculated using image logs will... more In this work, the process that the bedding dip and strike can be calculated using image logs will be explained by using a unique case study and a number of valuable image log interpretation examples. This job will be done in Gachsaran field, one of the most important Iranian fields, and the main reservoir that will be studied is Asmari reservoir, one of the most important Iranian oil and gas reservoirs.
By interpreting image logs, both the directions of drilling induced fractures parallel to the max... more By interpreting image logs, both the directions of drilling induced fractures parallel to the maximum horizontal in-situ stress direction and borehole breakouts parallel to the minimum horizontal in-situ stress direction can be calculated. In this work, 10 wells located in Gachsaran field were selected then the direction of drilling induced fractures and borehole breakouts in these wells was examined by using image logs and other geological log interpretation. This work was done in order to have a better understanding of structural geology in this field and also explain the methodology by showing the selected log interpretation examples from this field.
International Journal of Applied Sci, 2023
The Khalij limestone member, well-known for its abundant benthic facies, is situated in the middl... more The Khalij limestone member, well-known for its abundant benthic facies, is situated in the middle segment of the Gadvan shaly formation, boasting an average thickness of approximately 14 meters. This specific member is exclusively found below the surface, devoid of any exposed outcrops, and is characterized by the presence of easily identifiable orbitolinid limestone. Well logging techniques, such as Gamma Ray and Density measurements, prove particularly effective in identifying this distinct layer. The primary objective of this study was to conduct a comprehensive analysis of the lithostratigraphy and microstratigraphy within the Gadvan formation, with a specific emphasis on the Khalij limestone member. A regional stratigraphic assessment covered an extensive area of about 100,000 square kilometers in the Fars and Dezful regions within the Zagros region. To achieve this, data from 38 exploration and development wells were utilized, and approximately 1,400 microscopic thin sections from the Gadvan formation were meticulously examined. The paramount contribution of this research lies in the establishment of a representative type section for the Khalij limestone member, characterized by a thickness of 13 meters. Detailed microscopic analysis has revealed that this member predominantly comprises wackestone carbonate, featuring microfossils, particularly foraminifera from the orbitolindae family. Based on the observed species index, it has been determined to be of Barremian age and linked to a lagoon-like depositional environment.
https://www.akademiabaru.com/doc/ARAMV3\_N1\_P1\_8.pdf, 2014
https://www.akademiabaru.com/doc/ARAMV3\_N1\_P1\_8.pdf Image log technology is an advanced technolo... more https://www.akademiabaru.com/doc/ARAMV3_N1_P1_8.pdf
Image log technology is an advanced technology that helps us in finding the location, dip, azimuth, strike and type of faults in any science related to geology. Finding out this information from image logs is not so easy, and many geologists are looking for an industrial source with real examples of log interpretation to have a better understanding of this technology. Therefore, in this study, a unique case study and a number of valuable log interpretation examples were used, and the process was explained completely. This job was done in Gachsaran field, one of the most important Iranian fields, and the main reservoir is Asmari reservoir, one of the most important Iranian oil and gas reservoirs. A unique educational paper is produced from this study, which can be useful for other geologists who are interested in fault interpretation and image log technology.
Journal of Applied Sciences 23(1):34-46, 2023
Characterizing fracture properties in naturally fractured reservoirs poses a significant challeng... more Characterizing fracture properties in naturally fractured reservoirs poses a significant challenge. While well-testing remains valuable, it often fails to provide precise descriptions of these properties. Bridging this gap requires the integration of geological expertise to enhance fracture assessment. This study addresses the limitations of well-test analysis and explores the application of Conventional Image Logs in structural, fracture, and geomechanical analysis. However, effectively combining these applications with well-test analysis on a field scale reveals a substantial knowledge gap. A critical challenge in this context is the absence of a defined procedure for calculating the variable "σ," a crucial parameter for simulating fractured carbonate reservoirs using image log fracture density. Integrating geological knowledge is essential to reduce uncertainties associated with well-test analysis and provide more accurate characterizations of fracture properties. Image log data processing emerges as a valuable avenue for gaining insights into the static attributes of naturally fractured reservoirs. This study focuses on Characterizing fractures using data from ten image logs and Developing a more accurate simulation model through the interpretation of images, with a particular emphasis on OBM imaging. The main goals of this fracture study revolve around establishing correlations between fracture densities well by well within the simulation and enhancing the accuracy of the simulation model by incorporating fracture data from image logs. Borehole imaging tools such as FMI/FMS and OBMI-UBI play a pivotal role in identifying significant structural features, including faults, fractures, and bedding. Fine-tuning fracture parameters during the history matching process, while potentially time-consuming, significantly impacts other historical match parameters. Consequently, the reliability of reservoir simulation results, predictions, and recovery enhancement strategies hinges on the precision of fracture properties and their distribution within the model. Recent advances in interpretation techniques have expanded the horizons of image interpretation, enabling the creation of more accurate simulation models for fractured reservoirs using fracture data obtained from image logs. The overarching goal of this project is to comprehensively evaluate a fractured reservoir field by integrating data from ten individual wells. Keywords: Well-testing, fracture evaluation, Image log data, fracture density, simulation sensitivity analysis.
https://asb.scione.com/cms/abstract.php?id=273 , 2024
https://asb.scione.com/cms/abstract.php?id=273 Background and Objective: The Asmari Formation p... more https://asb.scione.com/cms/abstract.php?id=273
Background and Objective: The Asmari Formation presents substantial challenges in reservoir management due to its structural complexities. Traditional core sampling methods fall short of accurately characterizing the fractured regions, impacting the efficacy of reservoir exploitation. Current study aims to enhance the understanding of the Asmari reservoir's structural and fracture complexities to improve well-test analyses and establish a detailed structural model for fracture characterization. Materials and Methods: The Formation Micro Imager (FMI) and geological logs utilized in well ZE-15, located within the Asmari Formation, for our experimental design. The FMI data, collected between depths of 4374 and 4640 m, was instrumental in assessing structural dips and mapping natural fractures. This approach facilitated a comprehensive analysis of fracture properties and structural orientation, incorporating statistical analyses to interpret the data accurately. Results: The FMI logging revealed a consistent structural dip of 33 degrees towards S62W across the Asmari Formation. Three main fracture zones were identified at depths of 4377-4459 m (Zone 1), 4459-4480 m (Zone 2) and 4480-4574 m (Zone 3), displaying a predominant WNW-ESE strike direction. This orientation correlates with the Zeloi structure's longitudinal alignment and the bedding strike. Further, elliptical borehole shapes observed in FMI images and caliper readings suggested the direction of minimum and maximum horizontal stresses, providing insights into the stress orientations affecting the formation. Conclusion: The current study successfully delineated the structural and fracture complexities within the Asmari reservoir, offering crucial insights into its stress orientations and natural fracture systems. This enhanced understanding is vital for optimizing reservoir exploitation strategies and improving recovery rates from this challenging geological formation.
https://asb.scione.com/cms/abstract.php?id=272, 2024
https://asb.scione.com/cms/abstract.php?id=272 Background and Objective: Accessing the Asmari re... more https://asb.scione.com/cms/abstract.php?id=272
Background and Objective: Accessing the Asmari reservoir poses challenges due to its complex structure, affecting well-test analysis accuracy in delineating fracture properties. Traditional core sampling struggles in highly fractured regions, leading to low recovery rates in unfavorable reservoir sections. The main objective of this study is to explore the challenges of accurately characterizing the fracture properties of the Asmari reservoir due to its structural complexities. Specifically, it aims to assess the effectiveness of using advanced borehole imaging tools, namely Oil-Based Mud Imager (OBMI) and Ultrasonic Borehole Imager (UBI), as alternatives to traditional core sampling and well-testing methods. Materials and Methods: Well GS-325 utilized OBMI and UBI tools to explore the Asmari Formation. The study involved a meticulous examination of geological features and structural attributes to understand the factors contributing to the observed thickness. Interpretation included manual dip picking using sinusoid techniques, followed by the classification of dips into bed boundaries and fractures. Results: The investigation revealed geological variations affecting the expected thickness of the Asmari Formation, enhancing comprehension of its complexities. The study identified 517 fractures within the Asmari interval, elucidating structural intricacies within the reservoir. Conclusion: The study demonstrates the successful use of OBMI/UBI imaging tools for identifying fractures and structural details in the Asmari Formation, despite challenges in shifting from oil-based to water-based drilling fluids. KEYWORDS Oil based mud micro-imager tool, ultrasonic borehole imager tool, fracture, structural dip, bedding, structural complexity
https://asb.scione.com/cms/abstract.php?id=271, 2024
https://asb.scione.com/cms/abstract.php?id=271 Background and Objective: Exploration of carbon... more https://asb.scione.com/cms/abstract.php?id=271
Background and Objective: Exploration of carbonate reservoirs in structurally complex areas, particularly those overlain by extensive evaporate formations, poses significant challenges in structural delineation. Lack of adequate structural geology information, especially in naturally fractured reservoirs, hampers drilling operations. In Iran, insufficient data on fractured reservoirs have hindered drilling activities. This study aims to assess the impact of limited structural information on drilling operations in complex naturally fractured reservoirs and underscores the efficacy of borehole imaging tools in addressing these challenges. The primary objective is to establish a precise structural model for the Asmari reservoir in the Gachsaran field. Materials and Methods: Utilizing well site geologist reports and formation cuttings analysis, this research examines drilling challenges encountered in penetrating the lower Asmari reservoir. Oil-Based Mud Micro Imager-Ultrasonic Borehole Imager (OBMI-UBI) tools were deployed in the interval from 2117 to 2772 m to investigate discrepancies in predicted reservoir depths. Results: The analysis revealed a deviation in the well trajectory, with an initial northeast (NE) direction shifting gradually to southwest (SW) until reaching total depth (TD). Caprock and bedding dips plotted alongside the trajectory unveiled parallelism with the middle Asmari layers, indicating the need for a directional change to exit the reservoir successfully. Borehole imaging played a pivotal role in delineating structural complexities, providing crucial insights for the effective positioning of wells. Conclusion: Insufficient structural data in complex carbonate reservoirs pose significant challenges to drilling operations. However, the deployment of borehole imaging tools, as demonstrated in this study, enables precise structural modeling and enhances drilling efficiency in such environments.
International Conference on Mathematical and Computational Methods in Science and Engineering, 2015
Application of artificial neural networks in fracture characterization and modeling technology A... more Application of artificial neural networks in fracture characterization and modeling technology
Alizadeh, Mostafa and Junin, Radzuan and Mohsin, Rahmat and Movahed, Zohreh and Alizadeh, Mehdi and Alizadeh, Mohsen (2015) Application of artificial neural networks in fracture characterization and modeling technology. In: 17th International Conference on Mathematical and Computational Methods in Science and Engineering (MACMESE '15), 23-25 April, 2015, Kuala Lumpur, Malaysia.
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Abstract
Fracture characterization and modeling technology can characterize the fractures of naturally fractured reservoirs. In this work, a novel application of Artificial Neural Networks (ANNs) will be introduced which can be used to improve this technology. The new technique by using the feed-forward ANN with backpropagation learning rule can predict the fractures dip inclination degree of the third well using the data from the other two wells nearby. The result obtained showed that the ANNs model can simulate the relationship between fractures dips in these three wells which the multiple R of training and test sets for the ANN model are 0.95099 and 0.912197, respectively.
Item Type: Conference or Workshop Item (Paper)
Uncontrolled Keywords: neural networks, technology
Subjects: T Technology > TP Chemical technology
Divisions: Petroleum and Renewable Energy Engineering
ID Code: 60765
Deposited By: Fazli Masari
Deposited On: 28 Feb 2017 01:38
Last Modified: 02 Aug 2017 08:13
Arabian Journal of Geosciences, Mar 1, 2016
Movahed, Z., Junin, R., Amiri Bakhtiary, H., Taghavi Poor, S., Mohamadian, R. (2016). The evaluat... more Movahed, Z., Junin, R., Amiri Bakhtiary, H., Taghavi Poor, S., Mohamadian, R. (2016). The evaluation of borehole imaging result comparing with cores in Sarvak fractured and non- fractured reservoir, Arabian journal of Geosciences. https://link.springer.com/article/10.1007/s12517-015-2091-1
Abstract
Core samples are still today considered as the standard measurement against all other measurements which must be compared. Core analysis usually focuses on the worse portion of the reservoir due to the fact that core recovery has rarely been well in a highly fractured zone; hence, permeability measured from core sample is often not representative. Core analysis is a common method to identify small-scale fractures of the well and permeability and porosity; however, there are some limitations in the core procedure such as it is highly expensive and unidirectional and has a low recovery coefficient in fractured zone. In contrast, there tends to be a mistrust and even a suspicion of those logging instruments that make measurements which threaten to replicate or even replace the “sacred core.” Thus, image logs are more useful to study the subsurface fractures in these such cases and the logs which come closest to achieving this are the high-resolution micro resistivity (OBMI) and acoustic geological imaging (UBI). The core and OBMI-UBI result was matched in order to verify the log measurements. Furthermore, FMI data were integrated with other open-hole logs to derive a permeability curve. As demonstrated in the case studies, it is believed that the permeability in the basement could be reasonably evaluated using this method. As a result, this exercise has proven to be very valuable, not only for demonstrating the value of the log data, but also it has also highlighted some significant limitations of the core in water-based mud and oil-based mud systems.
Journal of African Earth Sciences
Integrating hydraulic flow unit concept and adaptive neuro-fuzzy inference system to accurately e... more Integrating hydraulic flow unit concept and adaptive neuro-fuzzy inference system to accurately estimate permeability in heterogeneous reservoirs: Case study Sif Fatima oilfield, southern Algeria
Author links open overlay panelFaycal Djebbas a, Ouafi Ameur-Zaimeche a, Rabah Kechiched a, Salim Heddam b, David A. Wood c, Zohreh Movahed e
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https://doi.org/10.1016/j.jafrearsci.2023.105027
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Abstract
Formation characteristics are a crucial requirement for reservoir modeling and they need to be constantly updated as new static and/or dynamic reservoir-property details become available. This improves reservoir interpretation while achieving a good history-matching for a better representation of the reservoir. This paper proposes a new method to estimate reservoir permeability in an oil-producing reservoir by applying two distinct cases: partially cored and completely non-cored wellbores. The approach involves the determination of hydraulic-flow units (HFU) using a flow-zone indicator (FZI) distribution to consider the dynamic aspect of the permeability, which strongly influences fluid flow through porous media. The FZI is clustered by normal probability analysis to identify the optimum number of HFU clusters. The estimated reservoir permeability is validated in static and dynamic reservoir models. For an accurate prediction of the FZI over the entire reservoir thickness, an adaptive-neuro-fuzzy-inference system (ANFIS) is developed using conventional well-log variables: (i) gamma-ray (GR), (ii) sonic (DT), (iii) density (RHOB), (iv) deep resistivity (DLL), and (iv) neutron porosity (NPHI) calibrated with the available core data. The static regression parameters root-mean-squared error (RMSE), mean absolute error (MAE), coefficient of determination (R2), and R2adjusted are used to evaluate the performance of the ANFIS model in predicting FZI to determine HFU for estimating reservoir permeability. To validate this approach, a matching quality check of the downhole and reservoir pressure is carried out using a dynamic reservoir simulation model. Historical data collected from wellbore OPW-1 drilled in the Sif Fatima oilfield (Algeria) are used to evaluate the accuracy of the proposed permeability-prediction framework. The ANFIS model can accurately and efficiently predict the FZI exhibiting R2, R2adjusted, RMSE, and MAE of approximately (≈0.981, ≈0.979, ≈0.014, ≈4,600E-08)), (≈0.933, ≈0.891, ≈0.032, ≈1.615E-03), and (≈0.970, ≈0.968, ≈0.018, ≈2.381E-04)) for the training, testing and complete dataset, respectively. When applied to predict reservoir permeability, the Hydraulic Flow Unit concept was able to generate accurate results from the predicted FZI data by applying the modified Kozeny-Carman equation with, R2, RMSE and MAE values of approximately ≈0.9702, ≈0.969, ≈9.604, and ≈4.398, respectively. The calculated permeability was validated successfully at well and field levels. Additionally, it generated more accurate history matches of the well and the reservoir pressure trends than the previous permeability model, and consequently improved the reservoir modelling workflow.
Current Research in Geoscience, 2022
Analytical Fractured Reservoir Characterization by using Geological and Petrophysical Logs Zohre... more Analytical Fractured Reservoir Characterization by using Geological and Petrophysical Logs
Zohreh Movahed1 and Farzaneh Aghajari2
1 Faculty of Petroleum and Renewable Energy Engineering, Springer, Karun Energy and Teleperformance, University Teknologi Malaysia - UTM, Malaysia
2 Department of Geology, National Industrial Cluster Program, Iran
Abstract
Due to structural complexities in some wells, higher than the expected thickness of the Asmari formation is found. Fracture intensity and deep-rooted fractures broadly increase the risk of unpredictable water production. The well-test analysis is not sufficient in describing fracture properties. Unfortunately, the core condition is poor in the fractured zones and cannot be used to provide reliable information. So, the objectives of this study are developing an accurate structural model for the Asmari reservoir, and fracture characterization in the borehole by interpreting image logs and comparing the log's image results with core data. Dip classification based on a geological log has the value of providing a direct demonstration of structural origin and detecting Asmari fault and fracture systems and their impact on production and answering structural issues. So, in this study, the borehole imaging tools were interpreted to find solutions for fracture systems and fracture attributes. Interpreting accurate structural dip determined the structural problem, thus bringing the precise location of the well within the Asmari reservoir. Fracture properties (open or closed), occurrence, orientation, spacing, and porosity were interpreted using an Image log. The high density of fractures seen on FMS image logs in the study well has been confirmed by inspection of the cores and the distinction between major and minor fracture types from the FMS image logs has been established following core review. As a result, this exercise has been confirmed to be very valuable, not only for indicating the value of the log data, but it has also emphasized some significant limitations of the core data. The amount of information extracted from the FMS image logs goes beyond that achieved from the core. This exercise has validated why image logs are the main source of fracture information in the oil fields of Iran.
Current Research in Geoscience
Volume 12 No. 1, 2022, 11-28
DOI: https://doi.org/10.3844/ajgsp.2022.11.28
Submitted On: 18 July 2022 Published On: 3 December 2022
How to Cite: Movahed, Z. & Aghajari, F. (2022). Analytical Fractured Reservoir Characterization by using Geological and Petrophysical Logs. Current Research in Geoscience, 12(1), 11-28. https://doi.org/10.3844/ajgsp.2022.11.28
Open AccessCopyright: © 2022 Zohreh Movahed and Farzaneh Aghajari. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Background and Objectives: Due to structural complexities in some wells, higher than the expected... more Background and Objectives: Due to structural complexities in some wells, higher than the expected thickness of Asmari formation is found. Fracture intensity and deep-rooted fractures broadly increase the risk of unpredictable water production. The well test analysis is not sufficient in describing fracture properties. Unfortunately, the core condition is poor in the fractured zones and cannot be used to provide reliable information. So, the objectives of this study are developing an accurate structural model for Asmari reservoir,fracture characterization in the borehole by interpreting image logs ,and comparing the log's image results with core data.Materials and Methods: Dip classification based on a geological log has the value of providing a direct demonstration of structural origin and detect Asmari fault and fracture systems and its impact on production and answer structural issue. So, in this study, the borehole imaging tools were interpreted to find solutions for fracture...
Environmental Science: an Indian journal, 2015
Structural analysis is the way to have a better understanding of structural geology in oil and ga... more Structural analysis is the way to have a better understanding of structural geology in oil and gas fields. By using the image log technology, we can do this analysis very well, but this process is complicated and it is still unknown to many researchers. Therefore, we decided to explain this process by using a unique case study and a number of valuableimage log interpretation examples. This jobwill be done in Gachsaran field, one of the most important Iranian fields, and the main reservoir that will be studied is Asmari reservoir, one of the most important Iranian oil and gas reservoirs. We aim to offer a unique educational paper that will be very useful for the other researchers who are interested in structural geology and image log technology. This job showed that the direction of bedding strike is almost NW-SE direction for theAsmari reservoir in the section of Gachsaran field.
Fractures provide the place for oil and gas to be reserved and they also can provide the pathway ... more Fractures provide the place for oil and gas to be reserved and they also can provide the pathway for them to move into the well, so having a proper knowledge of them is essential and every year the companies try to improve the existed softwares in this technology. In this work, the new technique is introduced to be added as a new application to the existed softwares such as Petrel and geoframe softwares. The data used in this work are image logs and the other geological logs data of tree wells located in Gachsaran field, wells number GS-A, GS-B and GS-C. The new technique by using the feed-forward artificial neural networks (ANN) with back-propagation learning rule can predict the fracture dip data of the third well using the data from the other 2 wells. The result obtained showed that the ANN model can simulate the relationship between fractures dips in these 3 wells which the multiple R of training and test sets for the ANN model is 0.95099 and 0.912197, respectively.
https://www.youtube.com/watch?v=M7x8LbC-yFc&t=34s
https://www.youtube.com/watch?v=M7x8LbC-yFc&t=34s
A Novel Analytical Technique for Evaluating Fractured and Non-Fractured Reservoirs, 2024
https://www.cambridgescholars.com/product/978-1-0364-0999-9 In the complex field of carbonate res... more https://www.cambridgescholars.com/product/978-1-0364-0999-9
In the complex field of carbonate reservoir evaluation, the intricate structural features present significant obstacles. This study tackles the essential task of structural delineation, with a particular focus on fractured reservoirs, and highlights the crucial influence of permeability on the performance of wells and reservoirs. The Oil Based Mud Micro-Imager - resistivity of invading zone (OBMI-Rxo) offers a high-resolution curve that is sensitive to fluid mobility near the borehole wall, although it is often underexploited by oil companies. Maintaining borehole stability after drilling is critical for ensuring the longevity of wells. This research introduces a holistic workflow that combines borehole imagery, petrophysical logs, the Modular Formation Dynamics Tester (MDT), Xpress Pressure Tool (XPT), and core samples for sophisticated formation evaluation in both carbonate fractured and clastic reservoirs. The study reveals new insights into reservoir structure, fracture detection, visualization of rock texture, and permeability distribution, thereby improving our understanding of well conditions in these challenging geological environments.