Browsing by Author "Hadjadj, Ahmed"

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3D numerical and experimental modelling of multiphase flow through an annular geometry applied for cuttings transport
(Elsevier, 2022) Ferroudji, Hicham; Rahman, Mohammad Azizur; Hadjadj, Ahmed; Ofei, Titus Ntow; Khaled, Mohamed Shafik; Rushd, Sayeed; Gajbhiye, Rahul Narayanrao
Accurate estimation of volume fraction and pressure gradient is considered indicating parameters of efficient cuttings transportation. It is vital, in this regard, to consider all parameters that can affect cuttings volume fraction and pressure drop during enrollment of the drilling process. The analysis was conducted based on the turbulent flow of a power-law fluid through an annular domain by employing the Finite Volume Method. In addition, dimensional relationships were developed with the Buckingham-π theorem. Before carrying out simulations, the numerical schemes were validated using actual measurements made with the flow loop system available in Texas A&M University at Qatar. The simulation results demonstrated the followings: (i) using a power-law type drilling fluid with a shear-thinning character would reduce energy consumption for an inclination greater than 45°; (ii) inclination angles from 45° to 60° would be least desirable for an effective cuttings transportation with a turbulent Ostwald-de Waele fluid
AI-Driven Optimization of Drilling Performance Through Torque Management Using Machine Learning and Differential Evolution
(Multidisciplinary Digital Publishing Institute (MDPI), 2025) Boukredera, Farouk Said; Hadjadj, Ahmed; Youcefi, Mohamed Riad; Ouadi, Habib
The rate of penetration (ROP) is the key parameter to enhance drilling processes as it is inversely proportional to the overall cost of drilling operations. Maximizing the ROP without any limitation can induce drilling dysfunctions such as downhole vibrations. These vibrations are the main reason for bottom hole assembly (BHA) tool failure or excessive wear. This paper aims to maximize the ROP while managing the torque to keep the depth of cut within an acceptable range during the cutting process. To achieve this, machine learning algorithms are applied to build ROP and drilling torque models. Then, a metaheuristic algorithm is used to determine the optimal technical control parameters, the weight on bit (WOB) and revolutions per minute (RPM), that simultaneously enhance the ROP and mitigate excessive vibrations. This paper introduces a new methodology for mitigating drill string vibrations, improving the rate of penetration (ROP), minimizing BHA failures, and reducing drilling costs
Development of an expert-informed rig state classifier using naive bayes algorithm for invisible loss time measurement
(Springer Nature, 2024) Youcefi, Mohamed Riad; Boukredera, Farouk Said; Ghalem, Khaled; Hadjadj, Ahmed; Ezenkwu, Chinedu Pascal
The rig state plays a crucial role in recognizing the operations carried out by the drilling crew and quantifying Invisible Lost Time (ILT). This lost time, often challenging to assess and report manually in daily reports, results in delays to the scheduled timeline. In this paper, the Naive Bayes algorithm was used to establish a novel rig state. Training data, consisting of a large set of rules, was generated based on drilling experts’ recommendations. This dataset was then employed to build a Naive Bayes classifier capable of emulating the cognitive processes of skilled drilling engineers and accurately recognizing the actual drilling operation from surface data. The developed model was used to process high-frequency drilling data collected from three wells, aiming to derive the Key Performance Indicators (KPIs) related to each drilling crew’s efficiency and quantify the ILT during the drilling connections. The obtained results revealed that the established rig state excelled in automatically recognizing drilling operations, achieving a high success rate of 99.747%. The findings of this study offer valuable insights for drillers and rig supervisors, enabling real-time visual assessment of efficiency and prompt intervention to reduce ILT.
Drill string torsional vibrations modeling with dynamic drill pipe properties measurement and field validation
(American Society of Mechanical Engineers (ASME), 2022) Boukredera, Farouk Said; Hadjadj, Ahmed; Youcefi, Mohamed Riad
This paper aims to present the drill string torsional dynamics through a lumped parameter modeling using the basic physical notions with continuous measurement of drill pipe mechanical properties (inertia, damping, and stiffness). The model represents the mechanical properties as a variable for each drilled stand. A rock bit interactions model is employed in the system considering the kinetic friction as variable and depends on surface drilling parameters and the well length. Field data, including surface and downhole recorded velocities, are used to validate the model by comparing both velocities and to confirm the existence of drill string vibrations together with the simulation results (bit velocity)
Effect of drill pipe orbital motion on non-Newtonian fluid flow in an eccentric wellbore : a study with computational fluid dynamics
(Springer, 2021) Ferroudji, Hicham; Hadjadj, Ahmed; Ofei, Titus Ntow; Gajbhiye, Rahul Narayanrao; Rahman, Mohammad Azizur; Qureshi, M. Fahed
To ensure an effective drilling operation of an explored well, the associated hydraulics program should be established care- fully based on the correct prediction of a drilling fluid’s pressure drop and velocity field. For that, the impact of the drill string orbital motion should be considered by drilling engineers since it has an important influence on the flow of drilling fluid and cuttings transport process. In the present investigation, the finite volume method coupled with the sliding mesh approach is used to analyze the influence of the inner cylinder orbital motion on the flow of a power-law fluid (Ostwald-de Waele) in an annular geometry. The findings indicate that the orbital motion positively affects the homogeneity of the power- law axial velocity through the entire eccentric annulus; however, this impact diminishes as the diameter ratio increases. In addition, higher torque is induced when the orbital motion occurs, especially for high values of eccentricity and diameter ratio; nonetheless, a slight decrease in torque is recorded when the fluid velocity increases
The effect of orbital motion and eccentricity of drill pipe on pressure gradient in eccentric annulus flow with Newtonian and non-Newtonian fluids
(Inderscience, 2020) Ferroudji, Hicham; Hadjadj, Ahmed; Ntow Ofei, Titus; Rahman, Mohammad Azizur
The correct prediction of the pressure gradient is the fundamental parameter to establish an effective hydraulics program, which enables an optimised drilling process. In the present work, the effect of the orbital motion of the drill pipe on the pressure drop in an eccentric annulus flow with Newtonian and non-Newtonian fluids is studied numerically for both laminar and turbulent regimes using finite volume method (FVM). Furthermore, the effect of eccentricity when the inner pipe makes an orbital motion is evaluated. Different behaviours are observed in laminar and turbulent regimes. In the laminar regime, the simulation results showed that an increase of the orbital motion speed causes a considerable increment of the pressure gradient for the Newtonian fluid. For the power-law, non-Newtonian fluid in the laminar regime, on the contrary, a decrease of the pressure gradient is observed due to the shear-thinning effect. In the turbulent regime the mentioned trends are predicted to be much weaker. As eccentricity increases, the pressure drop of the non-Newtonian fluid decreases with a more pronounced diminish in pressure drop when the drill pipe is in orbital motion for both laminar and turbulent flow regimes.
Evaluating Storage Potential and Integrity of Depleted Reservoirs for CO₂ Injection
(2025) Zakarya, Belimane; Youcefi, Mohamed Ryad; Benbrik, Abderrahmane; Hadjadj, Ahmed
As global industrial activity grows, carbon dioxide emissions increase, intensifying greenhouse effect and climate change and demanding solutions beyond renewable energy. This study investigates CO₂ sequestration in subsurface formations as a promising mitigation strategy to support international climate goals and reduce carbon levels. Using CMG 2021 software, different trapping mechanisms, including structural, residual, and solubility trapping, were evaluated in detail to determine their individual and combined contributions to overall storage capacity. Results show that integrating all three mechanisms increases storage potential by 30% compared with structural trapping alone. In addition, geological uncertainty was addressed through Monte Carlo simulations. For that, multiple realizations were generated by varying key reservoir parameters such as porosity, permeability and hysteresis-related parameter. This probabilistic approach allows for a more robust assessment of storage capacity variability and enhances prediction confidence. Furthermore, caprock integrity was evaluated using a two-way geomechanical coupling approach with the Bendis model. The findings indicate that injection-induced pressure reduces effective stresses within the caprock, which may promote tensile failures and create potential leakage pathways. This integrated analysis demonstrates that coupling numerical simulation and probabilistic tools support safer, more effective CO₂ storage, which offers a viable long-term solution for global climate change mitigation efforts.
The impact of orbital motion of drill pipe on pressure drop of non-newtonian fluids in eccentric annulus
(Penerbit Akademia Baru, 2020) Ferroudji, Hicham; Hadjadj, Ahmed; Azizur Rahman, Mohammad; Hassan, Ibrahim; NtowOfei, Titus; Haddad, Ahmed
For all drilling operation method used to explore a well, the hydraulics program design associated to the well must be carried out carefully. A wrong estimation of pressure drop of the drilling fluid in the annular space can induce several problems, like: stuck pipe, lost circulation and insufficient hole cleaning. ANSYS Fluent 18.2code based on the finite volume method (FVM) is employed to evaluate the orbital motion impact ofdrill pipe on frictional pressure drop of non-Newtonian fluids (Ostwald-de Waele and Herschel-Bulkley models) flowing in laminar and turbulent regimes where the inner cylinder (drill pipe) makes an orbital motion around the centre of the outer cylinder (casing) and pure rotation around its own axis. Moreover, impact of the eccentricity on frictional pressure drop is discussed. Numerical results exhibit that as the Reynolds number increases, effect of the orbital motion speed of the inner cylinder becomes more severe on frictional pressure drop of the Ostwald-de Waele fluid for laminar regime. However, after a certain speed, frictional pressure drop begins to decrease. In addition, increase of the eccentricity induces a decrease of frictional pressure drop of the Ostwald-de Waele fluid in which this effect is more pronounced when the inner cylinder makes orbital motion for both laminar and turbulent regimes
Modeling surge pressures during tripping operations in eccentric annuli
(Elsevier, 2021) Belimane, Zakarya; Hadjadj, Ahmed; Ferroudji, Hicham; Rahman, Mohammad Azizur; Qureshi, M. Fahed
The aim of this paper is to present a new numerical model to study the drilling fluid flow through eccentric annulus during tripping operations and to investigate the effect of the eccentricity on the annular velocity and apparent viscosity profiles. Many published works studied surge and swab phenomenon using simplified numerical models that do not consider the azimuthal variation of the shear stress in the eccentric annuli. In this paper, the developed numerical model takes into consideration this variation. Non-orthogonal, curvilinear coordinates were used to generate a body-fitted elliptic mesh that maps the irregular complicated eccentric annulus into a simple rectangle where flow equations can be discretized using the finite difference method then solved numerically. Besides, a commercial software (ANSYS Fluent 19R3) was used to support the findings of the numerical model. Results of these models were validated against the experimental data from literature where good agreement was observed with an average relative error of 2.6%, 3.8%, and 6.8% for the three Herschel-Bulkley fluids studied in the eccentric case. The profiles of velocity and viscosity were plotted, the contours showed that we cannot use an average velocity or a single value for the apparent viscosity to describe the drilling fluid flowing through an eccentric annulus, but, the whole profile should be used, instead. The developed numerical model was used in a parametric study to investigate the effect of eccentricity on the relationship between surge pressure and the relevant drilling parameters namely tripping velocity, annular geometry, and fluid rheological properties. The results showed that the eccentricity decreases the surge pressure independently of the previous parameters and that the rate of decrease varies from one parameter to another. The outcome of this parametric study was used to construct a surrogate model using Random Forest Regressor. Predictions from the surrogate model fit the numerical data very well with R-squared of 0.99 and 0.97 for training and test data, respectively
New model for standpipe pressure prediction while drilling using group method of data handling
(Elsevier, 2021) Youcefi, Mohamed Riad; Hadjadj, Ahmed; Boukredera, Farouk Said
The continuous evaluation of the measured Stand Pipe Pressure (SPP) against a modeled SPP value in real-time involves the automatic detection of undesirable drilling events such as drill string washouts and mud pump failures. Numerous theoretical and experimental studies have been established to calculate the friction pressure losses using different rheological models and based on an extension of pipe flow correlations to an annular geometry. However, it would not be feasible to employ these models for real-time applications since they are limited to some conditions and intervals of application and require input parameters that might not be available in real-time on each rig. In this study, we applied the Group Method of Data Handling (GMDH) to develop a trustworthy model that can predict the SPP in real-time as a function of mud flow, well depth, RPM and the Fan VG viscometer reading at 600 and 300 rpm. In order to accomplish the modeling task, 3351 data points were collected from two wells from Algerian fields. Graphical and statistical assessment criteria disclosed that the model predictions are in excellent agreement with the experimental data with a coefficient of determination of 0.9666 and an average percent relative error less than 2.401%. Furthermore, another data (1594 data points) from well-3 was employed to validate the developed correlation for SPP. The obtained results confirmed that the proposed GMDH-SPP model can be applied in real-time to estimate the SPP with high accuracy. Besides, it was found that the proposed GMDH correlation follows the physically expected trends with respect to the employed input parameters. Lastly, the findings of this study can help for the early detection of downhole problems such as drill string washout, pump failure, and bit balling
Numerical study of parameters affecting pressure drop of power-law fluid in horizontal annulus for laminar and turbulent flows
(Springer, 2019) Ferroudji, Hicham; Hadjadj, Ahmed; Haddad, Ahmed; Ofei, Titus Ntow
Efficient hydraulics program of oil and gas wells has a crucial role for the optimization of drilling process. In the present paper, a numerical study of power-law fluid flow through concentric (E = 0.0) and eccentric annulus (E = 0.3, E = 0.6 and E = 0.9) was performed for both laminar and turbulent flow regimes utilizing a finite volume method. The effects of inner pipe rotation, flow behavior index and diameter ratio on the pressure drop were studied; furthermore, the appearance and development of secondary flow as well as its impact on the pressure drop gradient were evaluated. Results indicated that the increment of the inner pipe rotation from 0 to 400 rpm is found to decrease pressure drop gradient for laminar flow in concentric annulus while a negligible effect is observed for turbulent flow. The beginning of secondary flow formation in the wide region part of the eccentric annulus (E = 0.6) induces an increase of 9% and a slight increase in pressure drop gradient for laminar and turbulent flow, respectively. On the other hand, the variation of the flow behavior index and diameter ratio from low to high values caused a dramatic increase in the pressure drop. Streamlines in the annulus showed that the secondary flow is mainly induced by eccentricity of the inner pipe where both high values of diameter ratio and low values of flow behavior index tend to prevent the secondary flow to appear
Numerical study of temperature and pressure effects of a yield-power law fluid flow on frictional pressure losses for laminar and turbulent regimes
(Taylor and Francis, 2024) Messaoud, Nadia; Hadjadj, Ahmed; Ferroudji, Hicham
The effective determination of pressure losses depends on accurate knowledge of the drilling fluid rheology. As the fluid circulates deeper around the wellbore, its rheological behavior undergoes significant alterations due to the variations in downhole conditions encountered. The present study investigates the effects of the rheological properties of Yield-power law fluid at various pressures and temperatures on annular pressure losses and velocity profiles. Simulations were performed using Computational Fluid Dynamics to examine the fluid flow in turbulent and laminar regimes. Comparison between numerical, experimental and slot approximation model results showed a good agreement. Results indicated that pressure losses have reduced in both regimes with increasing temperature, at a constant pressure. However the pressure has the opposite effect at a constant temperature. For a drilling fluid flow velocity of 1 m/s, the elevation of temperature from 25 °C to 90 °C, decreases the pressure drop gradient by (31% to 48%) at low and high- pressure conditions respectively. Whereas, the influence of increasing pressure on pressure losses is more apparent at 25 °C. Earlier transition from laminar to turbulent is observed with temperature rise. Therefore, the temperature effect on pressure losses in the turbulent region; is shown for different Generalized Reynolds numbers
Optimization survey of gas CO2 sequestration in the TAGS Algerian reservoirs
(International Gas Union, 2012) Hadjadj, Ahmed; Kherfellah, Haddoum N.
This work is devoted to present the experience of Gas CO2 Storage in Algeria. The study was done to optimise the best reservoir for Gas CO2 Storage. The risks name for the two Fields considered Field I & Field II, they are: Permeable Zone in Seal, Earthquake Induced Fracturing, Leakage - Undetected Fault, NW Fractures corridors (that linear features are connected fracture corridors and, with current injection plan, could propagate through seal allowing CO2 into potable aquifer), Injection Well Leakage (With increasing pressure an inadequate barrier in wellbore material provides a leakage path to potable aquifer or surface), Old Well Leakage (Inadequate completion or chemical alteration of wellbore material provides a leakage path to potable aquifer or surface), Exceeding Spill-Point (Restricted access to pore space within structure causes CO2 flow below spill point, leaking up-dip to unknown resource potential) and Migration Direction.
An overview of thermal mass flowmeters applicability in oil and gas industry
(Elsevier, 2017) Bekraoui, Amina; Hadjadj, Ahmed
Measuring and modeling flow has played a central role in predicting its behavior and its effects on the surroundings. Flow measurement is the basis of trade between producers, transporters, process plants, state and public marketers. To improve transactional operation, thermal flowmeters could provide direct mass flow measurement of gases and vapors over a wide range of process conditions without the need for density corrections based on pressure and temperature. The flow meters are classified according to the domain in which they are used and their operating principle. The goal of this work is to provide an overview of using thermal flow meter in hydrocarbons industries. The applicability of thermal flow meters is discussed by a simulation using one-dimensional mathematical model of thermal flow sensor
An overview of thermal mass flowmeters applicability in oil and gas industry
(Elsevier, 2017) Bekraoui, Amina; Hadjadj, Ahmed
Predictionofnaturalgashydratesformationusingacombinationofthermodynamicandneuralnetworkmodeling
(Elsevier, 2019) Rebai, Noura; Hadjadj, Ahmed; Benmounah, Abdelbaki; Abdallah, S.Berrouk; M.Boualleg, Salim
During the treatment or transport of natural gas, the presence of water, even in very small quantities, can trigger hydrates formation that causes plugging of gas lines and cryogenic exchangers and even irreversible damages to expansion valves, turbo expanders and other key equipment. Hence, the need for a timely control and monitoring of gas hydrate formation conditions is crucial. This work presents a two-legged approach that combines thermodynamics and artificial neural network modeling to enhance the accuracy with which hydrates formation conditions are predicted particularly for gas mixture systems. For the latter, Van der Waals-Platteeuw thermodynamic model proves very inaccurate. To improve the accuracy of its predictions, an additional corrective term has been approximated using a trained network of artificial neurons. The validation of this approach using a database of 4660 data points shows a significant decrease in the overall relative error on the pressure from around 23.75%–3.15%. The approach can be extended for more complicated systems and for the prediction of other thermodynamics properties related to the formation of hydrates
Rate of penetration modeling using hybridization extreme learning machine and whale optimization algorithm
(Springer link, 2020) Youcefi, Mohamed Riad; Hadjadj, Ahmed; Bentriou, Abdelhak; Boukredera, Farouk Said
Modeling the rate of penetration (ROP) plays a fundamental role in drilling optimization since the achievement of an optimum ROP can drastically reduce the overall cost of drilling activities. Evolved Extreme learning machine (ELM) with the evolutionary algorithms and multi-layer perceptron with Levenberg-Marquardt training algorithm (MLP-LMA) were proposed in this study to predict ROP. This paper focused mainly on two aspects. The first one was the investigation of the whale optimization algorithm (WOA) to optimize the weights and biases between input and hidden layers of ELM to enhance its prediction accuracy. The other was to adopt a prediction methodology that seeks to update the predictive model at each formation in order to reduce the dimension of input data and mitigate the effect of non real-time data such as the formation properties on the bit speed prediction. The prediction models were trained and tested using 3561 data points gathered from an Algerian field. The statistical and graphical evaluation criteria show that the ELM-WOA exhibited higher accuracy and generalization performance compared with the ELM-PSO and MLP-LMA. Furthermore, ELM-WOA was compared with two well-known ROP correlations in the literature, and the comparison results reveal that the proposed ELM-WOA model is superior to the pre-existing correlations. The findings of this study can help for the achievement of an optimum ROP and the reduction of the non-productive time. In addition, the outputs of this study can be used as an objective function during the real-time optimization of the drilling operation
Real-Time prediction of plastic viscosity and apparent viscosity for Oil-Based drilling fluids using a committee machine with intelligent systems
(Springer, 2022) Youcefi, Mohamed Riad; Hadjadj, Ahmed; Bentriou, Abdelak; Boukredera, Farouk Said
he prediction of drilling mud rheological properties is a crucial topic with significant importance in analyzing frictional pressure loss and modeling the hole cleaning. Based on Marsh viscosity, mud density, and solid percent, this paper implements a committee machine intelligent system (CMIS) to predict apparent viscosity (AV) and plastic viscosity (PV) of oil-based mud. The established CMIS combines radial basis function neural network (RBFNN) and multilayer perceptron (MLP) via a quadratic model. Levenberg–Marquardt algorithm was applied to optimize the MLP, while differential evolution, genetic algorithm, artificial bee colony, and particle swarm optimization were used to optimize the RBFNN. A databank of 440 and 486 data points for AV and PV, respectively, gathered from various Algerian fields was considered to build the proposed models. Statistical and graphical assessment criteria were employed for investigating the performance of the proposed CMIS. The obtained results reveal that the developed CMIS models exhibit high performance in predicting AV and PV, with an overall average absolute relative deviation (AARD %) of 2.5485 and 4.1009 for AV and PV, respectively, and a coefficient of determination (R2) of 0.9806 and 0.9753 for AV and PV, respectively. A comparison of the CMIS-AV with Pitt's and Almahdawi's models demonstrates its higher prediction capability than these previously published correlations
A stiff-String model for torque and drag analysis in directional wells
(Springer, 2022) Mayouf, Mansour; Hadjadj, Ahmed
Overcoming friction forces generated from the contact of tubulars with the wellbore is one of the most important challenges in directional drilling, hence the need to accurately predict these friction forces. This paper undertakes the issue of tubular friction modeling in directional wells and presents a new approach for calculating torque and drag which relies on the beam theory for large deformations in the vertical plane. A comparative study using the soft-string model, a commercial stiff-string model, and the proposed model is carried out. To effectively test the validity and limitations of the proposed model, two wells with different geometries are studied. Results indicate that the proposed model gives similar predictions of the axial force and torque compared to the other industry-validated models where the difference of values at surface did not exceed 1% in all operations for smooth trajectories. Opposed to the soft-string model, the proposed model is able to predict the contact side and provide a profiling of the bending moment across the drill string. It is also able to carry out radial clearance analysis which has been shown to be of great importance when tortuosity is an issue where an increase of up to 10.05% of axial force at surface was observed when the hole diameter was reduced from 0.40 to 0.18 m for a tortuous well. The proposed model suffers, however, from the inability to model the post-buckling behavior of tubulars, which could generally be solved by pairing it with already available buckling models
Study assesses materials to minimize mud losses in Algeria's Hassi Messaoud field
(2016) Haddoum, Nadia; Hadjadj, Ahmed; Benmounah, Abdelbaki