含水层储能(Aquifer Thermal Energy Storage,缩写为ATES)系统因其良好的储热能力和经济性受到国内外学者的广泛关注,其中含水层储热系统中运行参数和布井参数的设置直接影响储热效果,如何优化参数获得最佳工艺方案,对于推广储热工程现...含水层储能(Aquifer Thermal Energy Storage,缩写为ATES)系统因其良好的储热能力和经济性受到国内外学者的广泛关注,其中含水层储热系统中运行参数和布井参数的设置直接影响储热效果,如何优化参数获得最佳工艺方案,对于推广储热工程现场应用具有重要意义。为此,以浅层含水层储热性能作为优化目标,通过灰色关联度方法对比关键参数对储热性能的影响程度,采用多目标优化方法得到最佳储热方案。研究结果表明:①注入温度与含水层之间温差较大会削弱系统储热能力,同类型储热井之间的热干扰反而有利于储热性能;②含水层厚度和布井数量对热损失率影响较大,而注入排量和井距对热回收率影响较大,注入温度对二者的影响最小;③注入温度25℃、含水层厚度106.597 m、注入排量30 kg/s的单井系统为最佳储热方案。结论认为:①关键参数对热损失和热回收的影响程度不同,为提高储热性能有必要对二者进行均衡优化;②优化方案有效扩大了储热体积,减少了热损失同时提高了热回收,使整个系统热损失率和热回收率分别在原有基础上优化了12.69%和3.19%,可为ATES系统的合理设计提供参考。展开更多
In this paper, we propose a hybrid PML （H-PML） combining the normal absorption factor of convolutional PML （C-PML） with tangential absorption factor of Mutiaxial PML （M-PML）. The H-PML boundary conditions can be...In this paper, we propose a hybrid PML （H-PML） combining the normal absorption factor of convolutional PML （C-PML） with tangential absorption factor of Mutiaxial PML （M-PML）. The H-PML boundary conditions can better suppress the numerical instability in some extreme models, and the computational speed of finite-element method and the dynamic range are greatly increased using this HPML. We use the finite-element method with a hybrid PML to model the acoustic reflection of the interface when wireline and well logging while drilling （LWD）, in a formation with a reflector outside the borehole. The simulation results suggests that the PS- and SP- reflected waves arrive at the same time when the inclination between the well and the outer interface is zero, and the difference in arrival times increases with increasing dip angle. When there are fractures outside the well, the reflection signal is clearer in the subsequent reflection waves and may be used to identify the fractured zone. The difference between the dominant wavelength and the model scale shows that LWD reflection logging data are of higher resolution and quality than wireline acoustic reflection logging.展开更多
The quality factor(or Q value)is an important parameter for characterizing the inelastic properties of rock.Achieving a Q value estimation with high accuracy and stability is still challenging.In this study,a new meth...The quality factor(or Q value)is an important parameter for characterizing the inelastic properties of rock.Achieving a Q value estimation with high accuracy and stability is still challenging.In this study,a new method for estimating ultrasonic attenuation using a spectral ratio based on an S transform(SR-ST)is presented to improve the stability and accuracy of Q estimation.The variable window of ST is used to solve the time window problem.We add two window factors to the Gaussian window function in the ST.The window factors can adjust the scale of the Gaussian window function to the ultrasonic signal,which reduces the calculation error attributed to the conventional Gaussian window function.Meanwhile,the frequency bandwidth selection rules for the linear regression of the amplitude ratio are given to further improve stability and accuracy.First,the feasibility and influencing factors of the SR-ST method are studied through numerical testing and standard sample experiments.Second,artificial samples with different Q values are used to study the adaptability and stability of the SR-ST method.Finally,a further comparison between the new method and the conventional spectral ratio method(SR)is conducted using rock field samples,again addressing stability and accuracy.The experimental results show that this method will yield an error of approximately 36%using the conventional Gaussian window function.This problem can be solved by adding the time window factors to the Gaussian window function.The frequency bandwidth selection rules and mean slope value of the amplitude ratio used in the SR-ST method can ensure that the maximum error of different Q values estimation(Q>15)is less than 10%.展开更多
The existing methods for extracting the arrival time and amplitude of ultrasonic echo cannot eff ectively avoid the local interference of ultrasonic signals while drilling,which leads to poor accuracy of the echo arri...The existing methods for extracting the arrival time and amplitude of ultrasonic echo cannot eff ectively avoid the local interference of ultrasonic signals while drilling,which leads to poor accuracy of the echo arrival time and amplitude extracted by an ultrasonic imaging logging-while-drilling tool.In this study,a demodulation algorithm is used to preprocess the ultrasonic simulation signals while drilling,and we design a backpropagation neural network model to fit the relationship between the waveform data and time and amplitude.An ultrasonic imaging logging model is established,and the finite element simulation software is used for forward modeling.The response under diff erent measurement conditions is simulated by changing the model parameters,which are used as the input layer of the neural network model;The ultrasonic echo signal is considered as a low-frequency signal modulated by a high-frequency carrier signal,and a low-pass fi lter is designed to remove the high-frequency signal and obtain the low-frequency envelope signal.Then the amplitude of the envelope signal and its corresponding time are extracted as an output layer of the neural network model.By comparing the application eff ects of the various training methods,we fi nd that the conjugate gradient descent method is the most suitable method for solving the neural network model.The performance of the neural network model is tested using 11 groups of simulation test data,which verify the eff ectiveness of the model and lay the foundation for further practical application.展开更多
Accurate Q parameter is hard to be obtained, but there is great difference between Q measurements from different measurement methods in seismic physical modelling. The influence factors, stability and accuracy of diff...Accurate Q parameter is hard to be obtained, but there is great difference between Q measurements from different measurement methods in seismic physical modelling. The influence factors, stability and accuracy of different methods are analyzed through standard sample experiment and the seismic physical modelling. Based on this, we proposed an improved method for improving accuracy of pulse transmission method, in which the samples with similar acoustic properties to the test sample are selected as the reference samples. We assess the stability and accuracy of the pulse transmission, pulse transmission insertion, and reflection wave methods for obtaining the quality factor Q using standard and reference samples and seismic physical modeling. The results suggest that the Q-values obtained by the pulse transmission method are strongly affected by diffraction and the error is 50% or greater, whereas the relative error of the improved pulse transmission method is about 10%. By using a theoretical diffraction correction method and the improved measurement method, the differences among the Q-measuring methods can be limited to within 10%.展开更多
基金supported by the National Natural Science Foundation of China(No.41204094)Science Foundation of China University of Petroleum,Beijing(No.2462015YQ0506)
文摘In this paper, we propose a hybrid PML （H-PML） combining the normal absorption factor of convolutional PML （C-PML） with tangential absorption factor of Mutiaxial PML （M-PML）. The H-PML boundary conditions can better suppress the numerical instability in some extreme models, and the computational speed of finite-element method and the dynamic range are greatly increased using this HPML. We use the finite-element method with a hybrid PML to model the acoustic reflection of the interface when wireline and well logging while drilling （LWD）, in a formation with a reflector outside the borehole. The simulation results suggests that the PS- and SP- reflected waves arrive at the same time when the inclination between the well and the outer interface is zero, and the difference in arrival times increases with increasing dip angle. When there are fractures outside the well, the reflection signal is clearer in the subsequent reflection waves and may be used to identify the fractured zone. The difference between the dominant wavelength and the model scale shows that LWD reflection logging data are of higher resolution and quality than wireline acoustic reflection logging.
基金supported by the Special Fund of the Institute of Geophysics,China Earthquake Administration(Nos.DQJB19B02 and DQJB17T04)
文摘The quality factor(or Q value)is an important parameter for characterizing the inelastic properties of rock.Achieving a Q value estimation with high accuracy and stability is still challenging.In this study,a new method for estimating ultrasonic attenuation using a spectral ratio based on an S transform(SR-ST)is presented to improve the stability and accuracy of Q estimation.The variable window of ST is used to solve the time window problem.We add two window factors to the Gaussian window function in the ST.The window factors can adjust the scale of the Gaussian window function to the ultrasonic signal,which reduces the calculation error attributed to the conventional Gaussian window function.Meanwhile,the frequency bandwidth selection rules for the linear regression of the amplitude ratio are given to further improve stability and accuracy.First,the feasibility and influencing factors of the SR-ST method are studied through numerical testing and standard sample experiments.Second,artificial samples with different Q values are used to study the adaptability and stability of the SR-ST method.Finally,a further comparison between the new method and the conventional spectral ratio method(SR)is conducted using rock field samples,again addressing stability and accuracy.The experimental results show that this method will yield an error of approximately 36%using the conventional Gaussian window function.This problem can be solved by adding the time window factors to the Gaussian window function.The frequency bandwidth selection rules and mean slope value of the amplitude ratio used in the SR-ST method can ensure that the maximum error of different Q values estimation(Q>15)is less than 10%.
基金funded by the Sinopec Engineering Technology Research InstituteThe name of the project is the Research and Development of Drilling Wall Ultrasonic Imaging System(No.PE19011-1)。
文摘The existing methods for extracting the arrival time and amplitude of ultrasonic echo cannot eff ectively avoid the local interference of ultrasonic signals while drilling,which leads to poor accuracy of the echo arrival time and amplitude extracted by an ultrasonic imaging logging-while-drilling tool.In this study,a demodulation algorithm is used to preprocess the ultrasonic simulation signals while drilling,and we design a backpropagation neural network model to fit the relationship between the waveform data and time and amplitude.An ultrasonic imaging logging model is established,and the finite element simulation software is used for forward modeling.The response under diff erent measurement conditions is simulated by changing the model parameters,which are used as the input layer of the neural network model;The ultrasonic echo signal is considered as a low-frequency signal modulated by a high-frequency carrier signal,and a low-pass fi lter is designed to remove the high-frequency signal and obtain the low-frequency envelope signal.Then the amplitude of the envelope signal and its corresponding time are extracted as an output layer of the neural network model.By comparing the application eff ects of the various training methods,we fi nd that the conjugate gradient descent method is the most suitable method for solving the neural network model.The performance of the neural network model is tested using 11 groups of simulation test data,which verify the eff ectiveness of the model and lay the foundation for further practical application.
基金supported by the National Nature Science Foundation of China(No.41474112)the National Science and Technology Major Project(No.2017ZX05005-004)
文摘Accurate Q parameter is hard to be obtained, but there is great difference between Q measurements from different measurement methods in seismic physical modelling. The influence factors, stability and accuracy of different methods are analyzed through standard sample experiment and the seismic physical modelling. Based on this, we proposed an improved method for improving accuracy of pulse transmission method, in which the samples with similar acoustic properties to the test sample are selected as the reference samples. We assess the stability and accuracy of the pulse transmission, pulse transmission insertion, and reflection wave methods for obtaining the quality factor Q using standard and reference samples and seismic physical modeling. The results suggest that the Q-values obtained by the pulse transmission method are strongly affected by diffraction and the error is 50% or greater, whereas the relative error of the improved pulse transmission method is about 10%. By using a theoretical diffraction correction method and the improved measurement method, the differences among the Q-measuring methods can be limited to within 10%.
