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Papers by Hossein Mohammadrezaei

Research paper thumbnail of The effects of wrench-dominated basement-involved faults on folding of overlying strata in the Bahregansar anticline, western Persian Gulf, Iran

Comptes Rendus. Géoscience, 2022

The effects of wrench-dominated basement-involved faults on folding of overlying strata in the Ba... more The effects of wrench-dominated basement-involved faults on folding of overlying strata in the Bahregansar anticline, western Persian Gulf, Iran

Research paper thumbnail of A laboratory investigation of the geomechanical properties of graphite stabilized clayey sands

Arabian Journal of Geosciences, 2021

This study aimed to determine the effect of graphite additive on the strength parameters of claye... more This study aimed to determine the effect of graphite additive on the strength parameters of clayey sand. Compaction, unconfined compression strength, shear strength, and permeability tests on clayey sand samples were conducted under non-stabilized and stabilized conditions containing varying amounts of graphite. The results were analyzed, and the soil microstructure was investigated using scanning electron microscopy (SEM) and X-ray diffraction (XRD) on non-stabilized and stabilized samples. After 28 days, the results indicated an increase in graphite content and that curing increased the compression strength of the stabilized sample to 340% of that of the non-stabilized sample with a 20% graphite content. The graphite content increased the internal friction angle, reaching a maximum of 59% for the sample stabilized with 5% graphite. Cohesion, maximum dry unit weight, optimum water content, and permeability coefficient decreased by 12.5%, 7.3%, 21%, and 95.5%, respectively, in the stabilized sample with 25% graphite. SEM images indicated that the flocculated continuous structure of the soil resulted in a change in the engineering parameters studied.

Research paper thumbnail of Deciphering the relationship between basement faulting and two-phase folding in the Hendijan anticline, northwest Persian Gulf, Iran

Marine and Petroleum Geology, 2020

This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Research paper thumbnail of Optimization of the Horizontal-Well Hydraulic-Fracture Geometry From Caprock-Integrity Point of View Using Fully Coupled 3D Cohesive Elements

SPE Production & Operations, 2017

Summary Pre-analysis of the geometry of a hydraulically induced fracture, including fracture widt... more Summary Pre-analysis of the geometry of a hydraulically induced fracture, including fracture width, length, and height, plays a crucial role in a successful hydraulic-fracturing (HF) operation. Besides the geometry of the fracture, the injection rate should be optimal for obtaining desired results such as maintaining sufficient aperture for proppant placement, avoiding screenouts or proppant bridging, and also preventing caprock-integrity failure as a result of an extensively uncontrolled fracture in reservoirs. A sophisticated numerical model derived from the cohesive-elements method has been developed and validated using field data to obtain an insight on the optimal fracture geometry and injection rate that can lead to a safe and efficient operation. The HF operation has been conducted in an oil field in the Persian Gulf with the aim of enhanced oil recovery (EOR) from a limestone reservoir with low matrix permeability in a horizontal wellbore. The concept of the cohesive-element...

Research paper thumbnail of Optimization of the horizontal-well multiple hydraulic fracturing operation in a low-permeability carbonate reservoir using fully coupled XFEM model

International Journal of Rock Mechanics and Mining Sciences, 2019

Pre-analysis of the geometry and deviation of multiple hydraulically induced fractures is a decis... more Pre-analysis of the geometry and deviation of multiple hydraulically induced fractures is a decisive factor in the successful multiple hydraulic fracturing operations. Besides, fracture spacing should be optimal for obtaining desired results such as maintaining sufficient aperture for proppant placement, avoiding screen-outs and also preventing fracture closure or crossing multiple fractures. In fact, the final geometry and deviation of multiple hydraulic fractures are dramatically influenced by the interaction of multiple hydraulic fractures on each other known as stress shadow effect which is caused by fracture spacing and pore pressure change. Predicting the geometry and deviation of multiple hydraulic fractures is a challenging part of conducting this technology in Ilam reservoir due to low matrix permeability and naturally fractured nature of the reservoir. Accordingly, a fully coupled stress-diffusion XFEM model for initiation and propagation of multiple hydraulic fractures with five injection zones was prepared to optimize the effect of fracture spacing and pore pressure change on the multiple hydraulic fractures' deviation and geometry. Additionally, the XFEM model was verified by three approaches including field data, Stress Intensity Factor and KGD zero toughness solution wherein a very good agreement with negligible error was obtained for SIF, field data and KGD M-vertex solution. However, this study has confirmed that both pore pressure and stress shadows contribute to change the fracture geometry and its deviation significantly in Ilam reservoir. Also, increasing pore pressure between fractures, may affect the fracture geometry to be tighter in width and shorter in length. In addition, considering optimized fracture spacing about 75 m resulted in creation of very smooth, uniform and deeper multiple hydraulic fractures; so, there will be no closed fractures in DPH-02 horizontal wellbore and the possibility of crossing the furthest fracture by the second fracture significantly reduced when the fracture spacing was higher than 5 m.

Research paper thumbnail of Reservoir characterization of the Burgan Formation in northwestern Persian Gulf

Journal of Petroleum Science and Engineering, 2018

Lower Cretaceous sequences of the Burgan Formation are notable siliciclastic reservoirs in the Mi... more Lower Cretaceous sequences of the Burgan Formation are notable siliciclastic reservoirs in the Middle East. Despite of this importance, a little is known about various geological characteristics of this reservoir in Iranian northwestern part of the Persian Gulf. In this study, an integrated sedimentological and reservoir geological evaluation has been carried out on the Burgan reservoir using a complete dataset of drilled cores, core plugs, thin sections and petrophysical logs along with laboratory data including XRD analysis of all components to define grain's mineralogy and porosity-permeability data for reservoir quality evaluation. Depositional facies and environments are interpreted and correlated in sequence stratigraphic framework of targeted reservoir across the studied fields and then compared with stratigraphic equivalents in the Middle East. Seven facies types are recognized that indicate deposition in a transitional environment from siliciclastic-dominated delta setting into shallow-marine carbonate platform. Diagenesis study indicates a simple history of post-depositional events that includes near surface (marine) and shallow to deep burial realms. Diagenetic processes are grouped into two categories based on their effects on reservoir properties. They include porosity enhancing (i.e. dissolution and fracturing) and porosity reducing (compaction and cementation) diagenetic processes. Reservoir

Research paper thumbnail of Net pay determination by artificial neural network: Case study on Iranian offshore oil fields

Journal of Petroleum Science and Engineering, 2014

Determining productive zones has always been a challenge for petrophysicists. On the other hand, ... more Determining productive zones has always been a challenge for petrophysicists. On the other hand, Artificial Neural Networks are powerful tools in solving identification problems. In this paper, pay zone determination is defined as an identification problem, and is tried to solve it by trained Neural Networks. Proposed methodology is applied on two datasets: one belongs to carbonate reservoir of Mishrif, the other belongs to sandy Burgan reservoir. The results showed high precision in classifying productive zones in predefined classes with Classification Correctness Rate of more than 85% in both geological conditions. Applicability of proposed pay zone determination procedure in carbonate environment is a great advantage of developed methodology. Fuzzified output, being independent of core tests and verification with well tests results are of other advantages of Neural Network-based method of pay zone detection.

Research paper thumbnail of Net pay determination by Dempster rule of combination: Case study on Iranian offshore oil fields

Journal of Petroleum Science and Engineering, 2014

Net pay detection is a key stage in reservoir characterization for several purposes: reserve esti... more Net pay detection is a key stage in reservoir characterization for several purposes: reserve estimation, reservoir modeling and simulation, production planning, etc. Determining productive zones always is simultaneous with some amount of uncertainty due to lack of enough data, insufficiency of knowledge and wild-nature of petroleum reservoirs. It becomes even more challenging in carbonates, because of their highly heterogeneous environment. Conventionally, evaluating net pays is done by applying petrophysical cutoffs on well-logs, which results in crisp classification of pay or non-pay zones. In addition, cutoff based method is developed in sandstones, and does not provide suitable results in carbonates at all. Proposed methodology of this work, Dempster-Shafer Theory, is a generalization of Bayesian Theory of conditional probabilities. Net pays are studied in two oil reservoirs by this theory; one of them is carbonate reservoir of Mishrif, the other is sandy Burgan reservoir. For validation, results 2 are compared to well tests and output of conventional cutoff method. The advantages of using Dempster-Shafer Theory, comparing to conventional cutoff based method in studying net pays is: to have a continuous fuzzy output, based on geological facts, with high generalization ability and more compatibility with well test data.

Research paper thumbnail of The effects of wrench-dominated basement-involved faults on folding of overlying strata in the Bahregansar anticline, western Persian Gulf, Iran

Comptes Rendus. Géoscience, 2022

The effects of wrench-dominated basement-involved faults on folding of overlying strata in the Ba... more The effects of wrench-dominated basement-involved faults on folding of overlying strata in the Bahregansar anticline, western Persian Gulf, Iran

Research paper thumbnail of A laboratory investigation of the geomechanical properties of graphite stabilized clayey sands

Arabian Journal of Geosciences, 2021

This study aimed to determine the effect of graphite additive on the strength parameters of claye... more This study aimed to determine the effect of graphite additive on the strength parameters of clayey sand. Compaction, unconfined compression strength, shear strength, and permeability tests on clayey sand samples were conducted under non-stabilized and stabilized conditions containing varying amounts of graphite. The results were analyzed, and the soil microstructure was investigated using scanning electron microscopy (SEM) and X-ray diffraction (XRD) on non-stabilized and stabilized samples. After 28 days, the results indicated an increase in graphite content and that curing increased the compression strength of the stabilized sample to 340% of that of the non-stabilized sample with a 20% graphite content. The graphite content increased the internal friction angle, reaching a maximum of 59% for the sample stabilized with 5% graphite. Cohesion, maximum dry unit weight, optimum water content, and permeability coefficient decreased by 12.5%, 7.3%, 21%, and 95.5%, respectively, in the stabilized sample with 25% graphite. SEM images indicated that the flocculated continuous structure of the soil resulted in a change in the engineering parameters studied.

Research paper thumbnail of Deciphering the relationship between basement faulting and two-phase folding in the Hendijan anticline, northwest Persian Gulf, Iran

Marine and Petroleum Geology, 2020

This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Research paper thumbnail of Optimization of the Horizontal-Well Hydraulic-Fracture Geometry From Caprock-Integrity Point of View Using Fully Coupled 3D Cohesive Elements

SPE Production & Operations, 2017

Summary Pre-analysis of the geometry of a hydraulically induced fracture, including fracture widt... more Summary Pre-analysis of the geometry of a hydraulically induced fracture, including fracture width, length, and height, plays a crucial role in a successful hydraulic-fracturing (HF) operation. Besides the geometry of the fracture, the injection rate should be optimal for obtaining desired results such as maintaining sufficient aperture for proppant placement, avoiding screenouts or proppant bridging, and also preventing caprock-integrity failure as a result of an extensively uncontrolled fracture in reservoirs. A sophisticated numerical model derived from the cohesive-elements method has been developed and validated using field data to obtain an insight on the optimal fracture geometry and injection rate that can lead to a safe and efficient operation. The HF operation has been conducted in an oil field in the Persian Gulf with the aim of enhanced oil recovery (EOR) from a limestone reservoir with low matrix permeability in a horizontal wellbore. The concept of the cohesive-element...

Research paper thumbnail of Optimization of the horizontal-well multiple hydraulic fracturing operation in a low-permeability carbonate reservoir using fully coupled XFEM model

International Journal of Rock Mechanics and Mining Sciences, 2019

Pre-analysis of the geometry and deviation of multiple hydraulically induced fractures is a decis... more Pre-analysis of the geometry and deviation of multiple hydraulically induced fractures is a decisive factor in the successful multiple hydraulic fracturing operations. Besides, fracture spacing should be optimal for obtaining desired results such as maintaining sufficient aperture for proppant placement, avoiding screen-outs and also preventing fracture closure or crossing multiple fractures. In fact, the final geometry and deviation of multiple hydraulic fractures are dramatically influenced by the interaction of multiple hydraulic fractures on each other known as stress shadow effect which is caused by fracture spacing and pore pressure change. Predicting the geometry and deviation of multiple hydraulic fractures is a challenging part of conducting this technology in Ilam reservoir due to low matrix permeability and naturally fractured nature of the reservoir. Accordingly, a fully coupled stress-diffusion XFEM model for initiation and propagation of multiple hydraulic fractures with five injection zones was prepared to optimize the effect of fracture spacing and pore pressure change on the multiple hydraulic fractures' deviation and geometry. Additionally, the XFEM model was verified by three approaches including field data, Stress Intensity Factor and KGD zero toughness solution wherein a very good agreement with negligible error was obtained for SIF, field data and KGD M-vertex solution. However, this study has confirmed that both pore pressure and stress shadows contribute to change the fracture geometry and its deviation significantly in Ilam reservoir. Also, increasing pore pressure between fractures, may affect the fracture geometry to be tighter in width and shorter in length. In addition, considering optimized fracture spacing about 75 m resulted in creation of very smooth, uniform and deeper multiple hydraulic fractures; so, there will be no closed fractures in DPH-02 horizontal wellbore and the possibility of crossing the furthest fracture by the second fracture significantly reduced when the fracture spacing was higher than 5 m.

Research paper thumbnail of Reservoir characterization of the Burgan Formation in northwestern Persian Gulf

Journal of Petroleum Science and Engineering, 2018

Lower Cretaceous sequences of the Burgan Formation are notable siliciclastic reservoirs in the Mi... more Lower Cretaceous sequences of the Burgan Formation are notable siliciclastic reservoirs in the Middle East. Despite of this importance, a little is known about various geological characteristics of this reservoir in Iranian northwestern part of the Persian Gulf. In this study, an integrated sedimentological and reservoir geological evaluation has been carried out on the Burgan reservoir using a complete dataset of drilled cores, core plugs, thin sections and petrophysical logs along with laboratory data including XRD analysis of all components to define grain's mineralogy and porosity-permeability data for reservoir quality evaluation. Depositional facies and environments are interpreted and correlated in sequence stratigraphic framework of targeted reservoir across the studied fields and then compared with stratigraphic equivalents in the Middle East. Seven facies types are recognized that indicate deposition in a transitional environment from siliciclastic-dominated delta setting into shallow-marine carbonate platform. Diagenesis study indicates a simple history of post-depositional events that includes near surface (marine) and shallow to deep burial realms. Diagenetic processes are grouped into two categories based on their effects on reservoir properties. They include porosity enhancing (i.e. dissolution and fracturing) and porosity reducing (compaction and cementation) diagenetic processes. Reservoir

Research paper thumbnail of Net pay determination by artificial neural network: Case study on Iranian offshore oil fields

Journal of Petroleum Science and Engineering, 2014

Determining productive zones has always been a challenge for petrophysicists. On the other hand, ... more Determining productive zones has always been a challenge for petrophysicists. On the other hand, Artificial Neural Networks are powerful tools in solving identification problems. In this paper, pay zone determination is defined as an identification problem, and is tried to solve it by trained Neural Networks. Proposed methodology is applied on two datasets: one belongs to carbonate reservoir of Mishrif, the other belongs to sandy Burgan reservoir. The results showed high precision in classifying productive zones in predefined classes with Classification Correctness Rate of more than 85% in both geological conditions. Applicability of proposed pay zone determination procedure in carbonate environment is a great advantage of developed methodology. Fuzzified output, being independent of core tests and verification with well tests results are of other advantages of Neural Network-based method of pay zone detection.

Research paper thumbnail of Net pay determination by Dempster rule of combination: Case study on Iranian offshore oil fields

Journal of Petroleum Science and Engineering, 2014

Net pay detection is a key stage in reservoir characterization for several purposes: reserve esti... more Net pay detection is a key stage in reservoir characterization for several purposes: reserve estimation, reservoir modeling and simulation, production planning, etc. Determining productive zones always is simultaneous with some amount of uncertainty due to lack of enough data, insufficiency of knowledge and wild-nature of petroleum reservoirs. It becomes even more challenging in carbonates, because of their highly heterogeneous environment. Conventionally, evaluating net pays is done by applying petrophysical cutoffs on well-logs, which results in crisp classification of pay or non-pay zones. In addition, cutoff based method is developed in sandstones, and does not provide suitable results in carbonates at all. Proposed methodology of this work, Dempster-Shafer Theory, is a generalization of Bayesian Theory of conditional probabilities. Net pays are studied in two oil reservoirs by this theory; one of them is carbonate reservoir of Mishrif, the other is sandy Burgan reservoir. For validation, results 2 are compared to well tests and output of conventional cutoff method. The advantages of using Dempster-Shafer Theory, comparing to conventional cutoff based method in studying net pays is: to have a continuous fuzzy output, based on geological facts, with high generalization ability and more compatibility with well test data.