Journal of Petroleum Science and Technology
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Journal of Petroleum Science and Technologyendaily1Tue, 01 Feb 2022 00:00:00 +0330Tue, 01 Feb 2022 00:00:00 +0330Application of Pressure-Volume (P-V) Fractal Models in Modeling Formation Pressure and Drilling Fluid Determination in an Oilfield of SW Iran
https://jpst.ripi.ir/article_1271.html
Accurate knowledge of pore and fracture pressures is essential for drilling wells safely with the desired mud weight. By definition, overpressure occurs when the pore pressure is higher than the normal hydrostatic pressure and is associated with specific environmental conditions in a particular part of the earth. This study focuses on the formation pressure studies&rsquo; domain for an oilfield in SW Iran. It generally consists of carbonate rocks with no shale interbeds except for the Kazhdumi Formation. This study is based on information from 23 wells and the interpretation of seismic data. The effective, pore, and fracture pressure models are determined from combined geostatistical models and compared with fractal models. The highest correlation between the final effective pressure cube and the velocity cube is related to the lower Fahliyan Formation with 86% and Ilam with 71%, which indicates the accuracy of the modeled data with the original data. Based on the final formation pressure cubes, the maximum pore pressure is 10,000 psi in the Gadvan Formation up to the upper Fahliyan Formation, and the maximum fracture pressure is 13,000 psi in the lower Fahliyan up to the Gotnia Formation. Based on the Logratio matrix obtained from the pressure-volume (P-V) fractal model, the maximum overall accuracy (OA) in the dominant limestone intervals is 0.74 at depths of 2000-3000 meters, which is related to the Asmari to Sarvak Formations. Furthermore, it indicates a high correlation of the pore pressure cube model obtained from the combination of sequential Gaussian simulation (SGS) and co-kriging models with acoustic impedance inversion (AI) for minimizing the time and cost of drilling in new wells of the studied field.&nbsp;Optimization of Hole Cleaning in Deviated Wells Using Metaheuristic Algorithms
https://jpst.ripi.ir/article_1269.html
Field experience shows that the cutting transportation and hole-cleaning phenomena are essential during the drilling phase. Particularly in directional drilling, when the accumulation of cutting has caused some drilling problems such as drill string sticking, formation failure, slow rate of penetration, drill bit abrasion, and the like. Through the study, a novel method for efficient hole cleaning, considering different parameters such as flow rate, the drill bit nozzles&rsquo; flow area, the consistency and flow behavior indices in the same time using PSO and ACO algorithms were implemented. Moreover, Power Law has been considered for the fluid rheology model. Based on this, the research parameter shows that the PSO algorithm is much more accurate than the ACO algorithm, improving objective function by 50% and 4%, respectively. The performance of each algorithm was evaluated, and the results show that hole cleaning has been significantly improved. The flow rate and the bit nozzle size, which play key roles, were selected as optimization variables. Effective parameters on hole cleaning were evaluated, and the results before and after optimization showed a significant improvement in the model. The PSO and ACO algorithms have been coded in MATLAB software, and the results are compared to the results of the ant colony. The amount of PV and YP has an inverse effect on the increment of minimum velocity required for cutting transport. Various model analyses reveal that the PSO algorithm is more accurate and robust than the Ant colony algorithm.Study and Application of Combination Cementing Technology of Gypsum Salt Layer in Kuqa Piedmont Structure, Tarim Basin
https://jpst.ripi.ir/article_1270.html
Kuqa piedmont is the main battlefield of natural gas production in the oil field and the source of west-east gas transmission. The wellbore quality is related to the safety of well construction and production. However, the well cementation quality of the piedmont salt layer is affected by the narrow density window, low casing center degree, and narrow annular gap. Moreover, the qualified rate of well cementation has only been around 50% for many years, which seriously threatens the integrity and safety of the wellbore. Although wildcatters have conducted a series of technical research and practical exploration for many years, the actual application effect is not good. The problem of the inferior well cementation qualitied ratio in the gypsum salt layer is still prominent. Because of the above objective problems and technical limitations, this paper deeply analyzes the influencing factors of the well cementation, which has the qualitied ratio of the gypsum salt layer in the piedmont structure. Based on the three basic points of (1) casing running, (2) column centering, and (3) cementation leakage prevention, this paper studies and applies the combination cementation technology of reaming technology, coupled casing, and fine pressure control, aiming to provide new guidance for the development of the cementation operation of gypsum salt layer, the results of quality improvement and efficiency are remarkable.AVO Analysis of Bottom Simulating Reflector (BSR) for Hybrid Model of Gas Hydrate Distribution
https://jpst.ripi.ir/article_1267.html
Due to the substantial effect of the gas hydrate distribution model (cement, un-cement, or hybrid of both models) on the elastic properties (such as shear modulus, bulk modulus, Poisson&rsquo;s ratio, etc.), determining the distribution model in the hydrate-bearing sediments is a requirement for decreasing uncertainty in quantitative studies based on seismic velocities. Many different empirical and theoretical rock physics theories cover different ranges of rock properties. Among them, the Effective Medium Theory (EMT) is the most appropriate in quantitative studies of gas hydrate resources. Four types of hydrate distributions have been considered and divided into two cemented and un-cemented categories. EMT is one of the advanced rock physics modeling tools. This theory has been modified by introducing hybrid distribution models of gas hydrate instead of having assumptions about single models of hydrate distribution. Moreover, when a scientific manuscript is written, using dangling and misplaced modifiers are not suggested. On the other hand, one method to determine the gas hydrate distribution model can be performed by identifying AVO&rsquo;s class on the bottom simulating reflector (BSR); caused by the contrast between an overlying gas hydrate and underlying free gas sediments. This reflector mimics seafloor topography, cross-cuts stratigraphic reflections, and is controlled by thermodynamic conditions. The results of this study on conceptual models showed that in hybrid approach for hydrate distribution, AVO&rsquo;s class on BSR shows sensitivity to (1) the combination type of gas hydrate distributions models, (2) the total saturation of the gas hydrate and free-gas across the BSR.The Effect of Permeability Contrast in Percolation Reservoir Models on the Breakthrough Time Distribution
https://jpst.ripi.ir/article_1268.html
In waterflooding process, the time for breakthrough of injecting fluid into a production well is of great importance. Predicting this time helps in designing reservoir development plan. Due to uncertainties in reservoir characterization, estimating the breakthrough is not easy, so alternative methods to estimate quickly the breakthrough time is useful. The percolation method uses limited available reservoir data to predict the breakthrough time distribution, and it may be used for engineering applications. However, implementation of this to real reservoirs requires some adjustments. The aim of this study is to show how percolation approach can be used to real problems. In particular, the effects of permeability contrast between the reservoir and non-reservoir parts in the model are investigated. In order to use the breakthrough scaling function to more realistic reservoir models, a dimensionless breakthrough time was used. The analysis of the breakthrough time of models with zero permeability background (tk=0) and such time for the case of non-zero permeability background (tk=&alpha;k) shows a linear dependency which can be used to find breakthrough time distribution. Hence, this correction extends the applicability of the percolation method for predicting breakthrough time when permeability of the system background is not zero.Reservoir Quality Evaluation based on Integration of Artificial Intelligence and NMR-derived Electrofacies
https://jpst.ripi.ir/article_1256.html
Logarithmic Mean of Transverse relaxation time (T2LM) and total porosity of the Combinable Magnetic Resonance tool (TCMR) are the main parameters of the Nuclear Magnetic Resonance (NMR) log which provide very substantial information for reservoir evaluation and characterization. &nbsp;Reservoir properties, for example, porosity and permeability, free and bound fluid volumes, and clay-bound water, could be calculated through the interpretation of T2LM and TCMR. In this manuscript, an intelligent approach has been used by us to predict NMR log parameters and their corresponding electrofacies from well log data. We define NMR electrofacies as classes of NMR log parameters representing reservoir quality are defined by us. For this purpose, NMR logs and petrophysical data are available for two different formations situated in the Ahvaz field. Data from Ilam formation were applied in order to construct the intelligent models, the same as Asmari formation, data were applied for reliability evaluation of the created models. &nbsp;The outcome results reveal higher performance levels of the Neural Network (NN) technique compared to the neuro-fuzzy (NF) model. The synthetically generated T2LM and TCMR logs are then calculated for the four logged wells from the Ahvaz oilfield using a mathematical function, and they are named Virtual Nuclear Magnetic Resonance (VNMR) logs. Finally, VNMR logs were classified into a set of reservoir electrofacies by cluster analysis approach. &nbsp;Correlations between the VNMR electrofacies and reservoir quality based on porosity and permeability data helped evaluate the reservoir quality quickly, cost-effectively, and accurately.Performance Analysis of Enhanced Gas Recovery Approach
https://jpst.ripi.ir/article_1272.html
Most massive gas fields in Bangladesh are nearing the end of their production. As global energy demands rise due to the rising population and rapid urbanization, maximizing the use of available resources has become essential. The preparation of the field's measurement to extend field lifetime needs to get attention. One such measure is Enhanced Gas Recovery (EGR), a potential technique to maximize the efficiency of the recovery process, which utilizes fracturing, water flooding, and gas injections to increase gas production. This work presents a simulation study of the performance of three EGR techniques with linear, triangular, and corner injection well placements and analyzes the simulation results of the techniques. Simulation of water flooding, CO2 injection, and WAG (water alternating CO2 gas) techniques are performed to evaluate the performance of the reservoir under these injections, and a suggestion has been provided in favor of the suitable approach among them. The performances are evaluated based on two factors: how much additional gas has been recovered and the quality of the produced gas. After analyzing the results for each case scenario, it is concluded that CO2 injection can be applied to increase natural gas recovery up to 24.55% more than the base case model, while the water flooding model and WAG model contributed 16.57% and 8% more gas recovery, respectively. The EGR techniques are simulated using the GASWAT feature in the fully implicit formulation of the E300 compositional simulator, a tool of the ECLIPSE suite.Laboratory Study of the Application of a Novel Bio-Based Polymer to Synthesize Aphron Drilling Fluids
https://jpst.ripi.ir/article_1284.html
Aphron fluids are a special type of foam in which the gas bubble (air or any other gas) is surrounded by a double-walled layer consisting of surfactant and polymer. Therefore, it is more stable at high temperature and high pressure conditions due to being preserved by three layers. These fluids are widely used in industry. Today, the industry uses various types of polymers such as acrylamides, polyacrylamides and hydrolyzed acrylamides that are harmful to the environment.In this study, the possibility of using natural and biodegradable polymers such as Astragalus Gum and starch is investigated. The results showed that the Aphron fluid made from Astragalus Gum (extracted from a dissert plant) had higher volumetric yield than industrial polymers. Stability over time as well as rheological properties for Astragalus Gum is also acceptable. Also, it is found that increasing the polymer concentration, the stability and rheological properties increase, but in contrast, the volumetric yield decreases. The effect of salt and surfactant concentrations are also evaluated in this research. The results show that increasing the surfactant concentration increases the volumetric yield of the fluid. Increasing the surfactant concentration from 1 wt% to 2 wt% increases the volumetric efficiency of Aphron fluids by 5%. In general, according to the results obtained in this research work, it can be inferred that the performance of Astragalus Gum is better than industrial polymer for making Aphron fluids.Erosion Damage for Various Flow Regimes during Particle Transport in Oil Wells: CFD Study
https://jpst.ripi.ir/article_1285.html
Oil extraction from weak sandstone formations that fails under changing in situ stresses leads to fine migration in near wellbore region. Companies use selective completion practices or downhole filters to control particle production in oil wells . However there will always remain fines with various size dispersions that cause erosion damage in crude oil pipelines. Particles influence oil viscosity as well as oil density therefore impact flow regime rather than pressure drop in various depths. In this work we employ Fluent software to simulate particle transport with multiphase flow in annulus that models cutting extraction during drilling rather than pipes which simulates production process. By adjusting various dissimilar particle dispersion functions we step farther to estimate damage due to erosive flow under various flow regimes. Results show that since thin film of liquid slurry with high particle concentration forms near inner wall pipe in annular flow regime erosion damage is at its highest value. Outcomes also illustrate that at high drill pipe rotation rates flow conflicts therefore erosion damage in annulus increases significantly.Enhancement of efficiency of water removal from Bangestan crude oil by silica nanoparticles using imidazolium-based ionic liquids
https://jpst.ripi.ir/article_1286.html
The effect of coating silica nanoparticles by a number of 1-alkyl-3-methylimidazolium hexafluorophosphate ionic liquids of [Rmim][PF6] general formula (R= C10, C12, and C14) on the water removal efficiency of silica nanoparticles from crude oil emulsions has been studied in this work. The ionic liquids have been prepared and characterized by a comparison of their 1HNMR and FT-IR spectral data with those reported in the literature. The effects of factors including cation alkyl chain length and concentration of the ionic liquids prepared on the water separation efficiency of the demulsifier have also been investigated in order to determine the optimal values for the chain length and concentration of the ionic liquid. [C14mim][PF6] ionic liquid at a concentration of 1200 ppm was shown to be the most efficient ionic liquid among the ionic liquids studied. The water separation efficiency achieved using coated nanosilica under the optimal conditions determined was found to be 93.3%.The effect of porosity on the seismic waves velocities and elastic coefficients in a South-Western Iran's oil field
https://jpst.ripi.ir/article_1287.html
Petrophysical and geophysical laboratory measurements were performed on ⁽40⁾ samples made of sandstone and limestone in an Oil Field. Parameters including porosity, density and permeability were measured along with the of compressional and shear waves&rsquo; velocities of the samples under reservoir conditions. Also, the study of microscopic thin sections, factors affecting the velocity of waves including porosity, Poisson&rsquo;s ratio, density, pressure and pore type were investigated. The scattering of points in the velocity diagrams of elastic waves based on the petrophysical parameters of the rock indicates that the most important factor of velocity changes is the pore type in the samples in the same porosity value. So, &lsaquo;LMR&rsaquo; parameters were calculated using laboratory results of velocity measurement. The values of &lsaquo;LMR&rsaquo; parameters of seismic data were determined by the velocities of compressional and shear waves in the pre-stack stage seismic. Then, using seismic inversion, compressional and shear wave resistances were estimated and seismic sections with &lsaquo;&lambda;.&mu;&rsaquo; and &lsaquo;&mu;.&rho;&rsaquo; parameters were created. The results show that there is a good correlation between laboratory measurement of rock physics and pre-stack seismic data. Also, the factor affecting the velocity of waves, i.e., the pore types, should also be considered. Uncertainty in velocity values due to the diversity of pores can show differences in the velocity of elastic waves in the same porosity value to about ⁽1500⁾ m/s. Also, at a constant velocity, porosity changes of up to ⁽20⁾ percent are visible.Comparison of cementation factor determination by artificial neural network method and optimized experimental relations in carbonate rocks
https://jpst.ripi.ir/article_1288.html
The cementation factor is one of the basic parameters for the calculating water saturation and then hydrocarbon saturation of reservoirs. The best way to determine the cementation factor is through laboratory measurements. To generalize this coefficient for samples without laboratory measurements, experimental relationships versus petrophysical properties by researchers can be somewhat helpful. The method of artificial neural networks, with the help of training, validation, and data analysis, has given the can better results in determining the cementation factor of carbonate samples. It is one of the best method that can use the petrophysical data as training data and make acceptable predictions with analytical methods. Therefore, laboratory measurement of the cementation factor has been performed for 159 carbonate cores from the Sarvak formation in the southwest of Iran. For the studied samples, the cementation factor in porosity was determined as a quadratic equation with the highest correlation coefficient. In this study, the compatibility of experimental relationship shows better conformity by considering the permeability of each sample. Improvement of empirical relationships by the authors, Correlation coefficients between the laboratory data and the experimental relationships has been increased. It is better to use improved experimental relationships for the studied carbonate samples.To process the data, the best adapt the laboratory data, and present a suitable model, artificial neural network methods, have been used. The Bayesian Regularization algorithm with five hidden layers has the least error in the test, validation, and testing stages