Fracture is a common underground structure phenomenon,which can provide space and passage for the storage and migration of oil and gas.Borehole radar is a fast and high-resolution geophysical detection method,which ha...Fracture is a common underground structure phenomenon,which can provide space and passage for the storage and migration of oil and gas.Borehole radar is a fast and high-resolution geophysical detection method,which has been widely used in engineering,exploration and other fields.This paper mainly uses theoretical analysis and numerical simulation to study the variation law of the characteristics of the received borehole radar signal with the variation of fracture width.The Ricker wavelet is used as the pulse signal of the borehole radar.The results show that the amplitude of the signal received by the borehole radar first increases,then decreases,and finally tends to be a stable value with the increase of fracture width.The results have guiding significance for the detection of underground fractures and the estimation of fracture width by borehole radar.展开更多
In this article, numerical modeling of borehole radar for well logging in time domain is developed using pseudo-spectral time domain algorithm in axisymmetric cylindrical coordinate for proximate true formation model....In this article, numerical modeling of borehole radar for well logging in time domain is developed using pseudo-spectral time domain algorithm in axisymmetric cylindrical coordinate for proximate true formation model. The conductivity and relative permittivity logging curves are obtained from the data of borehole radar for well logging. Since the relative permittivity logging curve is not affected by salinity of formation water, borehole radar for well logging has obvious advantages as compared with conventional electrical logging. The borehole radar for well logging is a one-transmitter and two-receiver logging tool. The conductivity and relative permittivity logging curves are obtained successfully by measuring the amplitude radio and the time difference of pulse waveform from two receivers. The calculated conductivity and relative permittivity logging curves are close to the true value of surrounding formation, which tests the usability and reliability of borehole radar for well logging. The numerical modeling of borehole radar for well logging laid the important foundation for researching its logging tool.展开更多
It is very difficult to clearly detect the location of a burning area in a coal mine since it is hidden underground.So we conducted research on the distribution of the burning area before controlling it.Firstly,the or...It is very difficult to clearly detect the location of a burning area in a coal mine since it is hidden underground.So we conducted research on the distribution of the burning area before controlling it.Firstly,the original drilling technique was used to analyze and determine the loose and scope of caving of burning area through field test,and then obtained the gases and the temperature data in this area were according to the borehole data.By analyzing these data,we found out that the location of burning area concentrated in the loose and caving area;and finally,the location and development of the burning area within the tested area were accurately determined.Based on this theory,we used the ground penetrating radar(GPR) to find out the loose and caving scale in the burning area during the control process of the burning area,and then located the fire-extinguishing boreholes within target which we used to control burning fire in the section.A mobile comprehensive fire prevention and extinguishing system based on the three-phase foam fire prevention and control technique was then adopted and conducted in the burning area which took only 9 months to extinguish the 227,000 m 2 of burning area of 9# coal.This control technology and experience will provide a very important reference to the control of other coalfield fire and hillock fire in the future.展开更多
基金Supported by National Natural Science Foundation of China (Nos. 41874136 and 42074146)。
文摘Fracture is a common underground structure phenomenon,which can provide space and passage for the storage and migration of oil and gas.Borehole radar is a fast and high-resolution geophysical detection method,which has been widely used in engineering,exploration and other fields.This paper mainly uses theoretical analysis and numerical simulation to study the variation law of the characteristics of the received borehole radar signal with the variation of fracture width.The Ricker wavelet is used as the pulse signal of the borehole radar.The results show that the amplitude of the signal received by the borehole radar first increases,then decreases,and finally tends to be a stable value with the increase of fracture width.The results have guiding significance for the detection of underground fractures and the estimation of fracture width by borehole radar.
基金supported by the Open Fund of Key Laboratory of Geo-detection (China University of Geosciences,Beijing),Ministry of Education (No. GDL0805)
文摘In this article, numerical modeling of borehole radar for well logging in time domain is developed using pseudo-spectral time domain algorithm in axisymmetric cylindrical coordinate for proximate true formation model. The conductivity and relative permittivity logging curves are obtained from the data of borehole radar for well logging. Since the relative permittivity logging curve is not affected by salinity of formation water, borehole radar for well logging has obvious advantages as compared with conventional electrical logging. The borehole radar for well logging is a one-transmitter and two-receiver logging tool. The conductivity and relative permittivity logging curves are obtained successfully by measuring the amplitude radio and the time difference of pulse waveform from two receivers. The calculated conductivity and relative permittivity logging curves are close to the true value of surrounding formation, which tests the usability and reliability of borehole radar for well logging. The numerical modeling of borehole radar for well logging laid the important foundation for researching its logging tool.
基金funded by the National Natural Science Foundation of China (No. 51134020)the State Key Laboratory of Coal Resources and Mine Safety Foundation (No.SKLCRSM08x06)the Natural Science Foundation of Jiangsu Province (No. BK2009004)
文摘It is very difficult to clearly detect the location of a burning area in a coal mine since it is hidden underground.So we conducted research on the distribution of the burning area before controlling it.Firstly,the original drilling technique was used to analyze and determine the loose and scope of caving of burning area through field test,and then obtained the gases and the temperature data in this area were according to the borehole data.By analyzing these data,we found out that the location of burning area concentrated in the loose and caving area;and finally,the location and development of the burning area within the tested area were accurately determined.Based on this theory,we used the ground penetrating radar(GPR) to find out the loose and caving scale in the burning area during the control process of the burning area,and then located the fire-extinguishing boreholes within target which we used to control burning fire in the section.A mobile comprehensive fire prevention and extinguishing system based on the three-phase foam fire prevention and control technique was then adopted and conducted in the burning area which took only 9 months to extinguish the 227,000 m 2 of burning area of 9# coal.This control technology and experience will provide a very important reference to the control of other coalfield fire and hillock fire in the future.
