17 results on '"Wenshu Zha"'
Search Results
2. Physical Asymptotic-Solution nets: Physics-driven neural networks solve seepage equations as traditional numerical solution behaves
- Author
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Luhang Shen, Daolun Li, Wenshu Zha, Li Zhang, and Jieqing Tan
- Subjects
Fluid Flow and Transfer Processes ,Mechanics of Materials ,Mechanical Engineering ,Computational Mechanics ,Condensed Matter Physics - Abstract
Deep learning for solving partial differential equations (PDEs) has been a major research hotspot. Various neural network frameworks have been proposed to solve nonlinear PDEs. However, most deep learning-based methods need labeled data, while traditional numerical solutions do not need any labeled data. Aiming at deep learning-based methods behaving as traditional numerical solutions do, this paper proposed an approximation-correction model to solve unsteady compressible seepage equations with sinks without using any labeled data. The model contains two neural networks, one for approximating the asymptotic solution, which is mathematically correct when time tends to 0 and infinity, and the other for correcting the error of the approximation, where the final solution is physically correct by constructing the loss function based on the boundary conditions, PDE, and mass conservation. Numerical experiments show that the proposed method can solve seepage equations with high accuracy without using any labeled data, as conventional numerical solutions do. This is a significant breakthrough for deep learning-based methods to solve PDE.
- Published
- 2023
3. Automatic well test interpretation based on convolutional neural network for a radial composite reservoir
- Author
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Jinghai Yang, Wenshu Zha, Xuliang Liu, Detang Lu, and Daolun Li
- Subjects
Logarithm ,Mean squared error ,0211 other engineering and technologies ,convolutional neural network ,Energy Engineering and Power Technology ,02 engineering and technology ,Overfitting ,010502 geochemistry & geophysics ,01 natural sciences ,Convolutional neural network ,Plot (graphics) ,well testing interpretation ,Geochemistry and Petrology ,021108 energy ,lcsh:Petroleum refining. Petroleum products ,radial composite reservoir ,Dropout (neural networks) ,0105 earth and related environmental sciences ,Mathematics ,Well test (oil and gas) ,automatic interpretation ,Geology ,Function (mathematics) ,artificial intelligence ,Geotechnical Engineering and Engineering Geology ,lcsh:TP690-692.5 ,Economic Geology ,Algorithm - Abstract
An automatic well test interpretation method for radial composite reservoirs based on convolutional neural network (CNN) is proposed, and its effectiveness and accuracy are verified by actual field data. In this paper, based on the data transformed by logarithm function and the loss function of mean square error (MSE), the optimal CNN is obtained by reducing the loss function to optimize the network with “dropout” method to avoid over fitting. The trained optimal network can be directly used to interpret the buildup or drawdown pressure data of the well in the radial composite reservoir, that is, the log-log plot of the given measured pressure variation and its derivative data are input into the network, the outputs are corresponding reservoir parameters (mobility ratio, storativity ratio, dimensionless composite radius, and dimensionless group characterizing well storage and skin effects), which realizes the automatic initial fitting of well test interpretation parameters. The method is verified with field measured data of Daqing Oilfield. The research shows that the method has high interpretation accuracy, and it is superior to the analytical method and the least square method.
- Published
- 2020
4. Forecasting monthly gas field production based on the CNN-LSTM model
- Author
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Wenshu Zha, Yuping Liu, Yujin Wan, Ruilan Luo, Daolun Li, Shan Yang, and Yanmei Xu
- Subjects
General Energy ,Mechanical Engineering ,Building and Construction ,Electrical and Electronic Engineering ,Pollution ,Industrial and Manufacturing Engineering ,Civil and Structural Engineering - Published
- 2022
5. Predicting production-rate using wellhead pressure for shale gas well based on Temporal Convolutional Network
- Author
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Daolun Li, Zhiqiang Wang, Wenshu Zha, Jianjun Wang, Yong He, Xiaoqing Huang, and Yue Du
- Subjects
Fuel Technology ,Geotechnical Engineering and Engineering Geology - Published
- 2022
6. Automatic Reservoir Model Identification Method based on Convolutional Neural Network
- Author
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Wenshu Zha, Yan Xing, Zhankui Qi, Xuliang Liu, Lei He, and Daolun Li
- Subjects
0303 health sciences ,Artificial neural network ,Renewable Energy, Sustainability and the Environment ,business.industry ,Computer science ,Mechanical Engineering ,System identification ,Energy Engineering and Power Technology ,Pattern recognition ,Convolutional neural network ,03 medical and health sciences ,0302 clinical medicine ,Fuel Technology ,Geochemistry and Petrology ,030220 oncology & carcinogenesis ,Artificial intelligence ,business ,030304 developmental biology - Abstract
Well test analysis is a crucial technique to monitor reservoir performance, which is based on the theory of seepage mechanics, through the study of well test data, to identify reservoir models and estimate reservoir parameters. Reservoir model recognition is the first and essential step of well test analysis. It is usually judged by professionals’ experience, which results in low efficiency and accuracy. This paper is devoted to applying convolutional neural network (CNN) to well test analysis and proposes a new intelligent reservoir model identification method. Eight reservoir models studied in this paper include homogenous reservoirs with different outer boundaries such as infinite acting boundary, circular, single, angular, channel, U-shaped and rectangular sealing fault boundaries, and a radial composite reservoir with infinite acting boundary. Well testing data used in this paper, including actual field data and theoretical data, are generated by analytical solutions. To improve the classification accuracy of actual field data, noise processing was carried out on the data before training. The CNN that is most suitable for model recognition has been obtained through trial-and-error procedures. The availability of proposed CNN is proved with actual field cases of Daqing oil field, China. The method realizes the automatic identification of reservoir model with the total classification accuracy (TCA) of test data set of 98.68% and 95.18% for original data and noisy data, respectively.
- Published
- 2021
7. Convolution-Based Model-Solving Method for Three-Dimensional, Unsteady, Partial Differential Equations
- Author
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Wenshu Zha, Wen Zhang, Daolun Li, Yan Xing, Lei He, and Jieqing Tan
- Subjects
Arts and Humanities (miscellaneous) ,Cognitive Neuroscience - Abstract
Neural networks are increasingly used widely in the solution of partial differential equations (PDEs). This letter proposes 3D-PDE-Net to solve the three-dimensional PDE. We give a mathematical derivation of a three-dimensional convolution kernel that can approximate any order differential operator within the range of expressing ability and then conduct 3D-PDE-Net based on this theory. An optimum network is obtained by minimizing the normalized mean square error (NMSE) of training data, and L-BFGS is the optimized algorithm of second-order precision. Numerical experimental results show that 3D-PDE-Net can achieve the solution with good accuracy using few training samples, and it is of highly significant in solving linear and nonlinear unsteady PDEs.
- Published
- 2021
8. Deep CNN for removal of salt and pepper noise
- Author
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Wenshu Zha, Daolun Li, Yan Xing, Jian Xu, and Jieqing Tan
- Subjects
Pixel ,business.industry ,Computer science ,020206 networking & telecommunications ,Pattern recognition ,Salt-and-pepper noise ,Image processing ,02 engineering and technology ,Convolutional neural network ,Noise ,Filter design ,Computer Science::Computer Vision and Pattern Recognition ,Test set ,Signal Processing ,0202 electrical engineering, electronic engineering, information engineering ,020201 artificial intelligence & image processing ,Computer Vision and Pattern Recognition ,Artificial intelligence ,Electrical and Electronic Engineering ,business ,Image resolution ,Software - Abstract
Image denoising is a common problem during image processing. Salt and pepper noise may contaminate an image by randomly converting some pixel values into 255 or 0. The traditional image denoising algorithm is based on filter design or interpolation algorithm. There exists no work using the convolutional neural network (CNN) to directly remove salt and pepper noise to the authors’ knowledge. In this study, they utilise CNN with the multi-layer structure for the removal of salt and pepper noise, which contains padding, batch normalisation and rectified linear unit. In training, they divide images into three parts: training set, validation set and test set. Experimental results demonstrate that the architecture can effectively remove salt and pepper noise for the various noisy images. In addition, their model can remove high-density noise well due to the extensive local receptive fields of the deep neural networks. Finally, extensive experimental results show that their denoiser is effective for those images with a large number of interference pixels which may cause misjudgement. In a word, they generalise the application of CNN to salt and pepper noise removal and obtain competitive results.
- Published
- 2019
9. Surrogate modeling for porous flow using deep neural networks
- Author
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Luhang Shen, Daolun Li, Wenshu Zha, Xiang Li, and Xuliang Liu
- Subjects
Fuel Technology ,Geotechnical Engineering and Engineering Geology - Published
- 2022
10. Shale Digital Core Image Generation Based on Generative Adversarial Networks
- Author
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Yan Xing, Xingbao Li, Jieqing Tan, Daolun Li, Lei He, and Wenshu Zha
- Subjects
0303 health sciences ,Image generation ,Renewable Energy, Sustainability and the Environment ,Computer science ,Mechanical Engineering ,Distributed computing ,ComputingMethodologies_IMAGEPROCESSINGANDCOMPUTERVISION ,Energy Engineering and Power Technology ,03 medical and health sciences ,Adversarial system ,0302 clinical medicine ,Fuel Technology ,Geochemistry and Petrology ,030220 oncology & carcinogenesis ,Core (graph theory) ,Oil shale ,Generative grammar ,030304 developmental biology - Abstract
Stochastic reconstruction of digital core images is a vital part of digital core physics analysis, aiming to generate representative microstructure samples for sampling and uncertainty quantification analysis. This paper proposes a novel reconstruction method of the digital core of shale based on generative adversarial networks (GANs) with powerful capabilities of the generation of samples. GANs are a series of unsupervised generative artificial intelligence models that take the noise vector as an input. In this paper, the GANs with a generative and a discriminative network are created respectively, and the shale image with 45 nm/pixel preprocessed by the three-value-segmentation method is used as training samples. The generative network is used to learn the distribution of real training samples, and the discriminative network is used to distinguish real samples from synthetic ones. Finally, realistic digital core samples of shale are successfully reconstructed through the adversarial training process. We used the Fréchet inception distance (FID) and Kernel inception distance (KID) to evaluate the ability of GANs to generate real digital core samples of shale. The comparison of the morphological characteristics between them, such as the ratio of organic matter and specific surface area of organic matter, indicates that real and reconstructed samples are highly close. The results show that deep convolutional generative adversarial networks with full convolution properties can reconstruct digital core samples of shale effectively. Therefore, compared with the classical methods of reconstruction, the new reconstruction method is more promising.
- Published
- 2020
11. Pressure transient behaviors of hydraulically fractured horizontal shale-gas wells by using dual-porosity and dual-permeability model
- Author
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Wenshu Zha, John Yilin Wang, Detang Lu, and Daolun Li
- Subjects
Finite volume method ,Shale gas ,02 engineering and technology ,Mechanics ,010502 geochemistry & geophysics ,Geotechnical Engineering and Engineering Geology ,01 natural sciences ,Volumetric flow rate ,Permeability (earth sciences) ,Fuel Technology ,Adsorption ,020401 chemical engineering ,Perpendicular ,0204 chemical engineering ,Porosity ,0105 earth and related environmental sciences ,Parametric statistics - Abstract
A dual-porosity and dual-permeability (DPDP) model was developed to describe the fluids flow and transient pressure behaviors of multistage hydraulically fractured horizontal wells in shale-gas reservoirs by incorporating gas adsorption and gas permeability corrections. This 3-dimensional, 1-phase numerical model was developed using finite volume method and solved implicitly with unstructured PEBI (Perpendicular Bisection) gridding. Parametric studies were conducted to understand the pressure transient behaviors with effects of gas adsorption, permeability correction, transmissibility between fracture and matrix system (called inter-porosity flow ability, IPF), and natural fracture spacing. The results showed that pressure transient behaviors were not only controlled by the individual ultimate adsorption capacity (UAC) and IPF but rather the combination of IPF ability and UAC derived herein. The physics was that for a block by omitting the flow in matrix systems and accumulation term, the flow rate of free gas between the matrix cell and the fracture cell was equal to the flow rate caused by adsorbed or desorbed due to a pressure change in the matrix cell. This was the reason that if the IPF ability was relatively small, large amount of free gas would flow into the wellbore, which affected the pressure transient behaviors. This finding was quantified with a new correlation that was a function of IPF ability, UAC and pressure difference between fracture and matrix.
- Published
- 2018
12. Pressure transient analysis of low permeability reservoir with pseudo threshold pressure gradient
- Author
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Shufeng Liu, Lei Wang, Daolun Li, Detang Lu, and Wenshu Zha
- Subjects
Materials science ,Computer simulation ,business.industry ,020209 energy ,Flow (psychology) ,02 engineering and technology ,Mechanics ,Structural engineering ,Geotechnical Engineering and Engineering Geology ,Nonlinear system ,Fuel Technology ,020401 chemical engineering ,0202 electrical engineering, electronic engineering, information engineering ,Fluid dynamics ,Exponent ,Transient response ,0204 chemical engineering ,business ,Pressure gradient ,Parametric statistics - Abstract
Threshold pressure gradient (TPG) is an important mechanism for fluid flow through low-permeability reservoirs, which would explain the phenomena that pressure derivative curves exhibit a straight line of slope that is larger than zero after radial flow regime. A mathematical single-phase flow model incorporating pseudo TPG is proposed to describe the flow behavior in low permeability reservoirs. Fully implicit numerical simulation based on PEBI grid is developed to study the transient pressure response. Two field data are used to calibrate and validate the proposed model and the code. Based on one of field data, parametric studies are conducted to investigate the effect of minimum TPG, pseudo TPG and nonlinear exponent on the pressure transient response for a vertical well. We find that pseudo TPG can explain the unique and consistent characteristic of the pressure transient response in low permeability reservoirs. The finding is useful for petroleum engineers to interpret the field data to obtain some basic parameters for low permeability reservoirs.
- Published
- 2016
13. Automatic well test interpretation based on convolutional neural network for infinite reservoir
- Author
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Liping Gao, Zhou Ziqi, Daolun Li, Wenshu Zha, Jiahang Han, Xuliang Liu, and Jinghai Yang
- Subjects
Mean squared error ,Computer science ,02 engineering and technology ,010502 geochemistry & geophysics ,Geotechnical Engineering and Engineering Geology ,01 natural sciences ,Convolutional neural network ,Wellbore ,Permeability (earth sciences) ,Fuel Technology ,020401 chemical engineering ,Approximation error ,Skin factor ,0204 chemical engineering ,Oil field ,Pressure derivative ,Algorithm ,0105 earth and related environmental sciences - Abstract
The well testing technique is an important tool in estimating well and reservoir characteristics, such as permeability, skin factor and so on. For a long time, researchers have been searching for automatic well testing interpretation tools, but the results are disappointing. This paper proposes using convolutional neural network (CNN) as an automatic well test interpretation approach for infinite acting reservoirs. The CNN takes pressure change and pressure derivative data of the log-log plot for inputs. The wellbore storage coefficient, skin factor and reservoir permeability are redefined into a dimensionless group C D e 2 S as the output of the CNN. In this method, the best trained CNN structure is obtained by minimizing mean square error (MSE) and mean relative error (MRE). This new method is tested for its effectiveness and accuracy in Daqing oil field, China. It demonstrates that, for wells in infinite reservoir, CNN could be an effective automatic well test interpretation technique. CNN also shows the potential for more complicated scenarios.
- Published
- 2020
14. A dynamic and adaptive scheme for feature-preserving mesh denoising
- Author
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Jieqing Tan, Lei He, Yeyuan He, Yan Xing, and Wenshu Zha
- Subjects
Scheme (programming language) ,Surface (mathematics) ,Computer science ,Noise reduction ,020207 software engineering ,02 engineering and technology ,01 natural sciences ,Computer Graphics and Computer-Aided Design ,0104 chemical sciences ,010404 medicinal & biomolecular chemistry ,Robustness (computer science) ,Feature (computer vision) ,Modeling and Simulation ,0202 electrical engineering, electronic engineering, information engineering ,Polygon mesh ,Geometry and Topology ,Noise (video) ,Algorithm ,computer ,Software ,Dynamic mesh ,computer.programming_language - Abstract
Mesh denoising is a classical problem and has made great progress, but it has not been solved perfectly. Our paper presents an adaptive and dynamic mesh denoising method, which can remove noise effectively while preserving sharp features and visually meaningful fine-scale components. Most state-of-the-art approaches still fall short of robustly handling various noisy 3D models, because optimal parameters are usually selected manually, and remain unchanged for the whole model and throughout the whole denoising procedure. Actually, the parameters should be adaptively adjusted according to the feature intensity of different regions in each iteration and dynamically changed in subsequent iterations to avoid over-smooth. In this paper, the parameters are determined automatically and adjusted dynamically, which allows the real shape of the surface to be restored as much as possible, especially in feature regions. Extensive qualitative and quantitative experiments on various noisy meshes have demonstrated the effectiveness and robustness of our approach.
- Published
- 2020
15. Implicit Approximation of Neural Network and Applications
- Author
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Daolun Li, Wenshu Zha, and Detang Lu
- Subjects
Physical neural network ,Computer science ,Time delay neural network ,business.industry ,Deep learning ,Energy Engineering and Power Technology ,Geology ,Probabilistic neural network ,Fuel Technology ,Recurrent neural network ,Feedforward neural network ,Artificial intelligence ,Stochastic neural network ,business ,Nervous system network models - Abstract
Summary It is common practice that one of the reservoir properties is recognized as a complex function of several interrelated factors in neural-network applications used in oil-reservoir studies. Few methods are based on one reservoir property being recognized as a function of time and the spatial locations, which means that the reservoir-property data can be described as a time vector series. It is a great challenge for the artificial neural network to describe a time vector series because the neural network is unable to approximate a multivariate vector function effectively. By combining the principle of implicit curves and surfaces with the neural network, we present a novel way to process the time vector series. The method includes the following steps: mapping data, constructing an explicit function, training the neural network, extracting the isoline, and inverse mapping. This paper presents an application to predict the isotope-logging data in 2002 with the known data from 2001 and 2003.
- Published
- 2009
16. Generation and application of adaptive PEBI grid for numerical well testing(NWT)
- Author
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Daolun Li, Longjun Zhang, Detang Lu, and Wenshu Zha
- Subjects
Engineering drawing ,Computer science ,Grid - Published
- 2013
17. Implicit interpolation of time vector series
- Author
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Detang Lu, Wenshu Zha, and Daolun Li
- Subjects
Mathematical optimization ,Nearest-neighbor interpolation ,Trilinear interpolation ,Bilinear interpolation ,Stairstep interpolation ,Linear interpolation ,Spline interpolation ,Algorithm ,Multivariate interpolation ,Mathematics ,Interpolation - Abstract
Time vector series abound in many fields, which are different from time series. Based on mapping and implicit function interpolation, the method of implicit interpolation over time vector series is developed and studied. Time vector series are mapped into a sequence of closed curves or surfaces, which are seen as the interpolation data set. Based on the interpolation data set, the implicit interpolation function is constructed and from which an isoline is drawn. The inverse mapping of the isoline is the prediction of vector series at the new time. Based on the well logging data an application is given to predict the unknown isotope logging data of year 2004 with the known data of year 2003 and 2005 which shows the performance of the method.
- Published
- 2011
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