Iranian Journal of Oil and Gas Science and Technology

Abstract Accurate pore pressure estimation is a critical component of geomechanical modeling, essential for maintaining wellbore stability and optimizing drilling fluid density. This study proposes a Grey Wolf Optimizer-Supported Vector Machine (GWO-SVM) workflow to predict pore pressure in a complex carbonate reservoir in southwestern Iran. While traditional empirical correlations like Eaton and Bowers are widely used, their reliance on continuous calibration can be challenging. To address this, discrete Repeating Formation Test (RFT) pressure points were utilized to calibrate baseline empirical trends, creating continuous reference profiles for the entire depth. The GWO-SVM model was then deployed to automate the replication of these calibrated baselines from standard petrophysical logs (sonic, density, resistivity, porosity, and shale volume). Using a dataset from five wells (four for training, one for blind validation), the GWO optimally tuned the Support Vector Regression (SVR) hyperparameters. The model demonstrated exceptional fidelity in replicating the calibrated baseline on the blind test well, achieving an RMSE=37.96psi and an R^2=0.998. Finally, the 1D well-based predictions were integrated into a 3D geostatistical model using co-kriging to visualize pressure compartmentalization influenced by the local tectonic stress regime. This workflow offers a replicable, high-precision alternative for pre-drill pore pressure modeling in data-limited reservoir settings.

Abstract In this study, nanostructured homogeneous and functionally graded (FG) Ni-Co/SiC coatings were fabricated on aluminum substrates via electrodeposition using a square pulse current. The FG coating was produced by continuously varying the concentration of SiC particles (0–40 g/L) in the electrolyte, resulting in a graded particle distribution across the coating thickness. The microstructure and morphology of the coatings were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Mechanical and electrochemical properties were evaluated through microhardness testing, T-peel adhesion testing, pin-on-disk wear testing, erosion testing, and potentiodynamic polarization and impedance spectroscopy. The results revealed that the SiC content in the FG coating gradually increased from 0 wt.% at the substrate interface to 6 wt.% at the surface. Compared to the homogeneous Ni-Co/SiC coatings, the FG coating demonstrated 40% higher adhesion strength and twice the wear resistance. Additionally, the FG coating exhibited improved corrosion resistance and overall mechanical performance, highlighting its potential for demanding industrial applications.

Abstract Due to their geological complexity, the Persian Gulf gas fields require more in-depth investigation. The primary reservoir rocks are carbonate sediments, notably the Upper Permian Dalan and Lower Triassic Kangan Formations. The Dalan Formation consists predominantly of oolitic limestone successions, which conformably overlie the Faraghan Sandstone Formation and underlie, unconformably, the carbonate sediments of the Kangan Formation. The Kangan Formation, in turn, underlies the shaly Agar Formation. The boundary between these studied formations corresponds to the Permian–Triassic (P/T) global boundary. In this study, two critical reservoir parameters—porosity and permeability—of the Dalan and Kangan Formations were evaluated using the Nuclear Magnetic Resonance (NMR) method. A thorough understanding of reservoir porosity and permeability is essential for optimal field management and prolonging the productive lifespan of the gas field.
Based on petrophysical properties, the studied succession has been subdivided, from top to bottom, into four units, designated K1 through K4. The results revealed significant differences in the reservoir characteristics of each unit. Units K1 and K2 belong to the Kangan Formation, while units K3 and K4 correspond to the Dalan Formation. Unit K2 exhibits the lowest hydrocarbon potential in terms of reservoir quality, whereas unit K4 of the Dalan Formation shows the highest porosity and permeability values. The permeability of the studied sequence was estimated using three approaches derived from NMR data: the Schlumberger-Doll Research (SDR) model, the T2 (so-called) model, and the Free Flow and Swanson models, based on the calculated porosity. Comparison of the results indicated that the SDR model provides the most reliable permeability estimates.
For sedimentary modeling, the accurately determined porosity and permeability parameters were integrated with geological interpretations. The analysis of the upper and lower deposits across the P/T boundary indicates that erosional events significantly affected reservoir quality. The findings of this study can aid in predicting reservoir performance and reducing drilling risks within the studied basin.

Abstract The corrosion inhibition effects of two antibiotic compounds, tetracycline (TE) and streptomycin (ST), on the corrosion of copper sheets in 1 M hydrochloric acid were investigated using weight loss measurements, Tafel polarization, electrochemical impedance spectroscopy, scanning electron microscopy, molecular dynamics simulations, and quantum chemical calculations. The Tafel polarization results indicated that both inhibitors act as mixed-type inhibitors and showed that the inhibition efficiency of streptomycin is higher than that of tetracycline. In addition, the adsorption behavior of the inhibitors was found to be consistent with the Temkin adsorption isotherm. As a complementary approach, computational chemical studies were performed. Molecular dynamics simulations were used to evaluate the most stable configurations and adsorption energies of the two compounds on the Cu 100, Cu 110, and Cu 111 surfaces. The theoretical results provide substantial support for understanding the inhibition mechanism of the two antibiotic compounds and show good agreement with the experimental findings.

Abstract In steel production plants, such as those manufacturing sheets, pipes, and round bars, raw materials are annealed in preheating furnaces at approximately 1200 °C before undergoing hot deformation. Substantial oxidation and loss of raw steel materials occur in preheating furnaces, resulting in significant economic losses. A potential solution to reduce losses in this scenario is the application of protective ceramic coatings. This research investigates the effect of a ceramic coating based on Al₂O₃–SiO₂ on the oxidation behavior of steel sheets. The industrial-scale impact of the coating on the oxidation of steel slabs is also examined. The coating was applied using a spray method with slurry ceramic materials dispersed through a compressed air flow. Thickness measurement tests, scanning electron microscopy, and energy dispersive X-ray spectroscopy (EDS) analysis were conducted to evaluate the kinetics, microstructure, and oxidation behavior of the coatings. The findings indicated that the oxidation kinetics for uncoated steel sheets followed a parabolic trend, while the kinetics for ceramic-coated samples exhibited a slower logarithmic behavior. The application of the coating resulted in a reduction of the oxide layer thickness by less than 30% compared to the uncoated samples, attributed to a lower diffusion coefficient in the coated samples. Applying the ceramic coating on ST52 slabs in industrial tests led to a significant reduction in the oxide layer thickness and a more straightforward peel of the oxide layers. This showed that using such ceramic coating for materials in preheating furnaces could effectively reduce oxidation losses and enhance the mechanical quality of final products.

Abstract Fin-pass rolls are the latest series of rolls in electric resistance welding (ERW) pipe production lines that form the sheets to tubular shape and adjust the edges of the sheet for welding. The rolls (made of AISI 8622 steel) lose their proper function after about 10 years of operation due to severe wear and change of their original surface profile. The worn portions were removed by grinding and replaced by an AISI D2 high carbon steel ring to repair these rolls. After a short time of service (about one year), the edge of the repair ring was exposed to severe spalling and fracture. The present study investigated the causes of the rapid failure of the AISI D2 repair ring and proposed a solution to the problem. The surface morphology, hardness, and wear resistance were studied. Moreover, the stress analysis of fin-pass rolls was studied using ABAQUS 6.14 finite element software for the closer investigation of the failure mechanism. The leading cause of spalling was the inherent brittleness of the AISI D2 steel and the presence of a high-stress concentration at the edges of the repair ring. To overcome this problem, carburized AISI P20 steel, case hardened AISI 4140 steel, and hard chromium electroplated AISI 4140 steel were replaced, and the resulting properties were studied. The highest resistance to spalling and wear occurred with carburized AISI P20 steel because of the high surface hardness and the gradual increase of toughness from the surface to the depth in the carburizing process, increasing the wear resistance and retarding the growth of fatigue cracks.

Abstract Seismic well tying is a crucial part of the interpretation phase in exploration seismology. Tying wells usually involves forward modeling a synthetic seismogram from sonic and density logs and then matching the obtained synthetic seismogram to the seismic reflection data. A huge amount of time is required to deal with it, yet the outcome signal may not be satisfying and may be suffering a low cross correlation between the seismic signal and the synthetic one; it also requires a high quality synthetic trace. Another problem with the so-called manual tying is that the tying process is not repeatable, indicating that one can rarely obtain the same stretched and squeezed signal if the tying procedure is repeated. In recent years, some researchers have used the dynamic time warping (DTW) method to address well tying problems. They have obtained good results according to the correlation between the seismic signal and the warped synthetic signal. This research demonstrates that the result will be better if filtering is applied before tying, and then the warped signal is smoothed. We also propose a simpler algorithm for extracting a warped signal from the warping curve and the original synthetic trace, which gives rise to better performance for well tying.

Abstract The organic geochemical characterization of crude oil samples from the oil fields of the Niger delta was carried out using gas chromatography–-mass spectrometry (GC–-MS) to genetically characterize the oil samples in terms of their biomarker composition. Geochemical characteristics such as depositional environments, kerogen type, and source of organic matter were analyzed using aliphatic biomarkers as a supporting tool. Five samples were randomly collected from Tebidaba, Clough Creek and Azuzuama fields in Bayelsa State, Nigeria. The saturated hydrocarbons were analyzed using GC–MS. The n-alkanes, isoprenoids, biomarkers hopanes, and steranes fingerprints were extracted from chromatogram for m/z 57, 191, 217 values respectively. The results revealed that the five studied samples were characterized by C₂₉ sterane predominance and the presence of oleanane, depicting organic matter with vascular land plant material inputs and a deltaic contribution. Ternary plots showed that the oils were deposited in an estuarine environment. The pristane (Pr) /nC₁₇ versus phytane (Ph)/nC₁₈ showed that TEB 08 and WELL 2 are in the anoxic environment inferring kerogen II and a mixture of types I and II respectively. TEB 12, CCST, and AZU ST has kerogen type III deposited in an oxic environment.

Abstract Seismic modeling aids the geophysicists to have a better understanding of the subsurface image before the seismic acquisition, processing, and interpretation. In this regard, seismic survey modeling is employed to make a model close to the real structure and to obtain very realistic synthetic seismic data. The objective of this study is to analyze the resolution and illumination of the fault by designing appropriate 3D seismic survey parameters. The ray-based seismic modeling was built using 2D seismic data, geological reports, and the well logs in one of the oil fields in the southwest of Iran. A pre-stack depth migration simulator was used to evaluate the survey geometry on the resulting seismic image. The results proved that a survey designer could improve the image of the target in a seismic section by applying the ray-based analyses, with respect to illumination and resolution studies.

Abstract Random or incoherent noise is an important type of seismic noise, which can seriously affect the quality of the data. Therefore, decreasing the level of this category of noises is necessary for increasing the signal-to-noise ratio (SNR) of seismic records. Random noises and other events overlap each other in time domain, which makes it difficult to attenuate them from seismic records. In this research, a new technique is produced, by joining FX deconvolution (FXD) and a special kind of median filter in order to suppress random noise from seismic records. The technique is operated in some stages; firstly, FXD is tried to eliminate the Gaussian noise, and the median filter is fixed to diminish the spike-like noise. The synthetic dataset and field data examples (from an oil field in the southwest of Iran) have been employed to demonstrate that random noise reduction can be attained, while the signal content will not be destroyed considerably. The final results indicate the authority of the proposed strategy in suppressing random noises, whereas signal information is almost protected during the filtering.