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80th EAGE Conference and Exhibition 2018
- Conference date: June 11-14, 2018
- Location: Copenhagen, Denmark
- Published: 11 June 2018
1061 - 1073 of 1073 results
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Investigations of Coal Pore Surface Characteristics with the Integration of Pore Compressibility at High Pressures
More LessSummaryDuring coalbed methane (CBM) production, pore structure undergoes changes due to the pore compressibility of the coal matrix. Comprehensive depiction of pore structure challenges a critical intricacy and practicality, so in the current study Quantitative technique: Mercury intrusion porosimetry (MIP) is used for analyzing and characterizing the pore structure. The results from this study, shows the compressibility as 20.1–22.7×10–11 m2/N neglecting the effect of mercury (Hg) compressibility i.e., 4×10−11 m2/N, which is in good agreement with the previous research findings. Also, pore surface is analysed using three-dimensional (3D) reconstruction interface that has made from the qualitative data of Field emission scanning electron spectroscopy (FE-SEM) images of the sample with which it is capable to take advantage of both the above modalities, by providing better visualization of pore surface topography through 3D reconstructions and appropriate info regarding the constructions being visualized. Especially for the trivial and intricate pore structures, such as those in the coal matrix this technique finds its unique approach in effective quantification.
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Lateral Range Issue in ERT - Analogue Modelling with 2D and Quasi-3D Inversion
Authors P. Ułasiewicz and M. ZiobroSummaryThe goal of this paper was to examine the distortions caused by bodies out of profile line in Electrical Resistivity Tomography (ERT) survey. Analogue modelling with Wenner array was applied. Results of 2D inversion has proven to be highly affected by lateral range issue, while quasi-3D inversion was significantly less distorted. For surveys conducted in vicinity to resistive body high amplitude anomaly was observed. When resistive body was four times the electrode spacing away from the survey line the 2D inversion was not significantly affected by the body's presence. For quasi-3D inversion there were no significant false anomalies observed.
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Estimation of Elastic Properties of the Near Subsurface from Shallow Seismic Reflection Recordings
By M. StancuSummaryWe determine the P-wave and S-wave velocities after picking first-arrival travel-times and also the elastic modulus from the analysis of seismic data recorded using vertical component geophones only. We show that the inversion of the dispersion curves obtained for the fundamental and higher modes of surface waves provides accurate information about the S-wave velocity distribution into the near subsurface. Thin layers can be differentiated after the inversion of the higher mode of surface waves. Ultimately, based on the P-wave and S-wave velocities we estimate a series of elastic modulus which are used in geotechnical studies.
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Inversion of Apparent Resistivity Using Regularized Neural Network
More LessSummarySince the beginning of the nineteenth century, a significant evolution in optimization theory has been noticed. In the past lots of statistical algorithm have been used to invert apparent resistivity to get layer parameters. But these algorithm are not very stable with very wide range of values. This paper shows the application of a statistically sound algorithm called as neural network which is based on the analogy of human brain. In this paper we have used regularized neural network for the inversion purpose.The inverted model parameters was found to be independent of the search space, thereby showing the robustness of the algorithm.
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Detection of Landslide Direction Based On HVNR Method
Authors M. Kazemnia Kakhki, F. Peters, J. Webe Mansour and S. Hooshmand GhazviniSummaryLandslide is a destructive phenomenon that causes great damage hence, it is important to reduce these losses by its recognition. Therefore, in this study it is tried to find landslide directivity in a village in Golestan Province named Narges Chal in North of Iran by HVNR method. to achieve this goal, analysis of spectral ratios of horizontal to vertical azimuthal variations of ambient noise (HVNR) recorded by the portable seismometers were accomplished to get information about the directional resonance phenomena. Afterwards, site response directivity by recorded noise analysis was investigated and the results were compared to geological features. For this purpose, four broadband seismometers were used, which were deployed linearly in various directions to monitor landslide properly. The results of HVNR were compared to Geotechnical drilling data that were consistent with the obtained results. The results proved that techniques based on spectral analysis of horizontal to vertical ratios can be useful to check the site effect directional features. it is noticed that there is a prevailing orientation approximately N-S (approximately 0 to 30).The conducted survey showed that this directivity is in the general direction of fractures and faults in the region and also topography dip.
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Inversion of Self-Potential Anomaly Using Laplace Crossover Operator Based Genetic Algorithm
By T. RajkumarSummaryThis paper addresses the approach to invert parameters of different buried structures using their self-potential (SP) anomalies. This approach involves a Laplace Crossover (LX) operator based Genetic Algorithm (GA) to invert synthetic SP anomaly of buried sphere, cylinder and inclined sheet. GA is used to determine depth, shape factor, polarization angle, origin of anomaly, electric current dipole for sphere and cylinder and half width along with the mentioned parameters for inclined sheet. This study of the synthetic examples shows that the proposed GA works very well with both noise free and noise corrupted data. Since it gives good convergence of the inverted data to the original values of synthetic examples, it can also be used in interpretation of real field complex SP data.
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Artificial Neural Networks Using Regularized Logistic Regression Cost Function: A Robust Lithofacies Classifier
More LessSummaryIn the past decade, a lot of progress in the field of Artificial Intelligence have been made in developing classification models to cater the needs of Geophysical Data Processing. This paper focuses on the application of regularization of the logistic regression cost function in the Neural Network Model to improve the generalization capability of the model. At the same time, making the model architecture better by hyper-parameter tuning is essential. This work caters to the classification of Lithofacies using Well Log Data like density log, neutron porosity log and gamma ray log.
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Feasibility Study of Fresh Water Storage Capacity in Asmari-Jahrum Formation, Chahpir Anticline
Authors M. Owji, R. Azin, M. Riazi, H. Bahrami, R. Ranjbar and D. FarokhianSummaryOne technique to mitigate water shortage in southern cities of Iran is water extraction from Asmari-Jahrum aquifer. In an appropriate aquifer, surface evidence indicates departure of karstic spring from outcrops of this aquifer. In this study, a geological survey was conducted in this area to investigate surface evidence and evaluate the quality of the Asmari-Jahrum aquifer in the Chahpir anticline. Evaluation of Asmari-Jahrum Formation outcrops reveals a strong fractured area and karstic formation due to action of tectonic forces and dissolution of rock minerals. In addition, a karstic spring with 6098 ppm water quality were found in the north of anticline. Thin-section study indicates precipitation of carbonate sediments during Eocene and cementation of the rock. This factor makes average porosity 14.31% and average permeability 0.2 md in laboratory measurements. These evidences in Chahpir anticline suggests Asmari-Jahrum formation as an appropriate aquifer in this region.
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Using Flow Diagnostics to Quantify the Effects of Reservoir Mobility and Wettability in Carbonate Reservoirs
Authors F. Alhashmi and S. GeigerSummaryThis research paper explores how very fast screening methods, so-called “flow diagnostics”, can help us explore how a realistic range of geological uncertainties and model scenarios impact flow behaviours in a complex carbonate reservoir. Flow diagnostics were implemented using MATLAB® Reservoir Simulation Toolbox (MRST). MRST provides the functionality to compute approximate dynamic properties (e.g. time-of-flight) directly on the grid of the reservoir model. A synthetic but geologically realistic sector-scale reservoir model, which serves as an analogue for the Arab D formation, was used to learn and establish the flow diagnostics workflow in MRST. An analysis of the uncertainties inherent to carbonate reservoir rock typing and their effect on reservoir performance is presented along with an analysis of the impact of wettability and mobility on reservoir performance. In addition a comparison of different metrics which approximate reservoir dynamics in carbonate reservoirs is given. Testing in MRST shows that flow diagnostic simulations take negligible time (i.e. in seconds), hence a large number of model scenarios and realizations can be explored and ranked based on their dynamic behaviour. This in turn will enable us to select appropriate models for full-physics simulations that capture the full uncertainty inherent in the reservoir description.
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Modeling Gas-Condensate Reservoir Performance in Multiphase Radial Flow Systems
More LessSummaryThis study proposes an alternative and rapid analytical methodology to forecast reservoir performance in multiphase radial flow gas-condensate systems. The proposed analytical solution for flow above the dew point pressure reasonably coincided with the line-source solution for flow above the dew point, thus, the analytical methodology can be used as an alternative to forecast reservoir performance in multiphase radial flow gas-condensate systems.
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Numerical Study on Methane Hydrate Dissociation in Lab-Scale Sandstone Core
Authors H. Eslami, B. Raji, M.J. Ameri Shahrabi and M. SabahSummaryIn current work, a 2D axisymmetric simulation of the gas production from hydrates in a porous sandstone core was conducted to study the behavior of gas production using depressurization method. The core model included three phases: hydrate, methane, and water. The decomposition reaction process, mass transfer, two-phase flow and heat transfer effects were included the model. The Darcy’s law was applied for the two-phase flow of water and gas in porous media and the hydrate was assumed to be stagnant. The Kim et al. (1987) kinetic model was used to determine hydrate dissociation rate and Reported values of the intrinsic rate constant and activation energy by Kim et al. (1987) and Clarke and Bishnoi (2001) were used in kinetic reaction equation in two various cases. In the energy balance equation the heat convection, conduction, consumption associated with hydrate decomposition and transfer from the surroundings were considered as well and the governing equations were solved using Finite Volume method. At last, by comparing the simulation results with experimental data, it is seen that the values of constant parameters of the intrinsic rate constant and activation energy suggested by Clarke and Bishnoi (2001) are more accurate to model hydrate kinetic reaction.
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A Fast Approach to Ensemble Appraisal and Reservoir Performance Predictions
Authors C.C. Onwunyili and K.D. StephenSummaryIt is only when the underlying uncertainties in reservoir model parameters are quantified that proper reservoir management decisions can be made. In this paper, we present an approach for making posterior inferences from the ensemble of reservoir models generated during history matching. The strength of the approach lies in the fact that it is faster than the predominantly used methods. It relies on high quality proxy models developed through a Genetic Programming Based Symbolic Regression. As a result, the expense of solving the forward problem is avoided at this appraisal stage. However, the probability distribution of parameters is initially unknown so the model space is resampled systematically according to the posterior probability density function. This results in the calculation of the Bayesian statistical measures of model plausibility and the correlations of the model parameters. The effectiveness of the approach is demonstrated here on model realisations generated using a Genetic Algorithm, but it is equally applicable to models generated through any other stochastic search methods. The results suggest that the new approach is an accurate and fast alternative to the existing methodologies for ensemble appraisal and stochastic reservoir performance forecast. MCMC resampling with the proxy model takes minutes instead of hours.
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Water-cut Metering by Flow Electrical Resistivity Measurement Method
Authors H. Asaadian, B. Soltani Soulgani and R. NajafiSummaryAccuracy of well performance data increases the chance of success in field management. Similarity water-cut monitoring helps to control the well during drilling and production stages. In this paper it was tried to design an experimental setup and particular tests. Then based on the gathered data, the effect of flow water-cut changes in the test pipe on flow electrical resistivity value between two electrodes which are placed in the pipe is investigated. The higher water cut was, the less flow resistivity measured. Rate of mixture resistivity decreasing is higher in lower water cut (between 8 to 50%). Also two matched equations are gained to predict the water cut for known flow electrical resistivity in two different range of water cut.
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