2.5维海洋非线性共轭梯度反演应用效果研究
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摘要
为了研究频率域2.5维非线性共轭梯度反演在海洋天然气水合物探测中的实际应用效果,利用美国Scripps研究所在South Hydrate海域采集的可控源电磁探测数据进行2.5维非线性共轭梯度反演计算,结合其他地球物理方法在同一海区的研究结果,综合分析2.5维反演计算的准确性和有效性。结果表明,非线性共轭梯度反演能够清晰地反映出该区域海底面以下1~2 km地层的电导率结构分布,其局部反演结果与地震反射、地震层序、测井分析结果基本一致,且对小尺寸异常、浅层高阻体分辨力较强,尤其在海洋天然气水合物探测方面具有较大潜力。
This paper aims to research the application effect of 2.5-dimension nonlinear conjugate gradient inversion in frequency domain in the field of natural gas hydrate detection. The effectiveness of self developed2.5 dimensional nonlinear conjugate gradient inversion algorithm has been tested through the data obtained from the South Hydrate sea area, Oregon, the United States. These data was collected through controlled source electromagnetic detection by the Scripps Institution of Oceanography in 2004. Beneath the seafloor of this area,free gas and gas hydrate have been proved to exist. Many different kinds of geophysical exploration methods have been applied within this zone. The inversion results of nonlinear conjugate gradient algorithm clearly illustrate the electrical conductivity distribution of the area 1-2 km under seafloor. The results have a remarkable meaning in the comparison research of the OCCAM inversion result for the same region. Furthermore, the details of nonlinear conjugate gradient inversion conform to the conclusions of marine magnetotelluric method, seismic reflection method, seismic sequence stratigraphy and ocean drilling programs. Therefore, the 2.5-dimension nonlinear conjugate gradient algorithm is capable of reflecting the conductivity distribution of shallow seafloor rather deliberately and exactly. This inversion method shows great potential in application, especially for small-scale reservoir, shallow buried resistivity and marine gas hydrate.
This paper aims to research the application effect of 2.5-dimension nonlinear conjugate gradient inversion in frequency domain in the field of natural gas hydrate detection. The effectiveness of self developed2.5 dimensional nonlinear conjugate gradient inversion algorithm has been tested through the data obtained from the South Hydrate sea area, Oregon, the United States. These data was collected through controlled source electromagnetic detection by the Scripps Institution of Oceanography in 2004. Beneath the seafloor of this area,free gas and gas hydrate have been proved to exist. Many different kinds of geophysical exploration methods have been applied within this zone. The inversion results of nonlinear conjugate gradient algorithm clearly illustrate the electrical conductivity distribution of the area 1-2 km under seafloor. The results have a remarkable meaning in the comparison research of the OCCAM inversion result for the same region. Furthermore, the details of nonlinear conjugate gradient inversion conform to the conclusions of marine magnetotelluric method, seismic reflection method, seismic sequence stratigraphy and ocean drilling programs. Therefore, the 2.5-dimension nonlinear conjugate gradient algorithm is capable of reflecting the conductivity distribution of shallow seafloor rather deliberately and exactly. This inversion method shows great potential in application, especially for small-scale reservoir, shallow buried resistivity and marine gas hydrate.
引文
[1]Weitemeyer K,S Constable,K Key,et al.Imaging Submarine Gas Hydrate Using EM Methods[C]//Lecture presented at MARELEC conference at the Marine Establishment in Amsterdam,Netherlands,2006.
[2]Arnold Orange,Kerry Key,Steven Constable.The feasibility of reservoir monitoring using time-lapse marine CSEM[J].Geophysics,2009,74(2):21-29.
[3]Yuguo Li,Steven Constable.2D marine controlled-source electromagnetic modeling:Part 2—The effect of bathymetry[J].Geophysics,2007,72(2):63-71.doi:10.1190/1.2430647
[4]Yutaka Sasaki,Max A Meju.Useful characteristics of shallow and deep marine CSEM responses inferred from 3D finite-difference modeling[J].Geophysics,2009,74(5):67-76.
[5]Ali Moradi Tehrani,Evert Slob.Applicability of 1D and 2.5D marine controlled source electromagnetic modelling[J].Geophysical Prospecting,2013,S1(61):602-613.
[6]陈光源,杜立彬,景建恩,等.2.5维海洋可控源电磁反演算法及影响参数研究[J].地球物理学进展,2016,31(4):1796-1802.
[7]Unsworth M,Oldenburg D.Subspace inversion of electromagnetic data:application to mid-ocean-ridge exploration[J].Geophys J Int,1995,123(1):161-168.
[8]Mac Gregor L M,Sinha M C,Constable S C.Electrical resistivity structure of the Valu Fa Ridge,Lau Basin,from marine controlled-source electromagnetic sounding[J].Geophysical Journal International,2001,146(1):217-236.
[9]Abubakar A,Habashy T M,Druskin V L,et al.2.5D forward and inverse modeling for interpreting low-frequency electromagnetic measurements[J].Geophysics,2008,73:165-177.
[10]Weitemeyer K,Gao G Z,Constable S,et al.the practical application of 2D inversion to marine controlled-source electromagnetic data[J].Geophysics,2010,75(6):199-211.
[11]Kerry K,Jeffrey O.A parallel goal-oriented adaptive finite element method for 2.5-D electromagnetic modelling[J].Geophys J Int,2011,186(1):137-154.
[12]Yuguo Li,Kerry Key.2D marine controlled-source electromagnetic modeling:Part1—An adaptive finite-element algorithm[J].Geophysics,2007,72(2):51-62.
[13]Kerry Key.MARE2DEM:a 2-D inversion code for controlled-source electromagnetic and magnetotelluric data[J].Geophys J Int,2016,207:571-588.
[14]杨梅霞,张胜业,贾豫葛.海洋大地电磁二维正演及结果分析[J].现代地质,2001,15(1):98-102.
[15]沈金松,孙文博.二维海底地层可控源海洋电磁响应的数值模拟[J].石油勘探,2009,48(2):187-194.
[16]刘颖.海洋可控源电磁法二维有限元正演及反演[D].青岛:中国海洋大学,2014.
[17]Polak E.Computational methods in optimization:A unified approach[M].New York:Academic Press,1971.
[18]Magnus R.Hestenes and Eduard Stiefel.Methods of conjugate gradients for solving linear systems[J].J Research Nat Bur Standards,1952,49:409-436.
[19]Fletcher R,Reeves C.Function minimization by conjugate gradients[J].Comput J,1964,7:149-154.
[20]G H Liu,J Y Han,H D Qi,et al.Convergence analysis on a class of conjugate gradient methods[J].Acta Mathematica Scientia,1998,18(2):11-16.
[21]何继善.海洋电磁法原理[M].北京:高等教育出版社,2012.
[22]Anne M Trehu,Ernst R Flueh.Estimating the thickness of the free gas zone beneath Hydrate Ridge,Oregon continental margin,from seismic velocities and attenuation[J].Journal of Geophysical research,2001,106(B2):2035-2045.
[23]Johanna Chevallier,Anne M Trehu,Nathan L Bangs,et al.Seismic sequences stratigraphy and tectonic evolution of southern hydrate ridge[J].Proceedings of the Ocean Drilling Program,Scientific Results,2006,204:1-29.
[2]Arnold Orange,Kerry Key,Steven Constable.The feasibility of reservoir monitoring using time-lapse marine CSEM[J].Geophysics,2009,74(2):21-29.
[3]Yuguo Li,Steven Constable.2D marine controlled-source electromagnetic modeling:Part 2—The effect of bathymetry[J].Geophysics,2007,72(2):63-71.doi:10.1190/1.2430647
[4]Yutaka Sasaki,Max A Meju.Useful characteristics of shallow and deep marine CSEM responses inferred from 3D finite-difference modeling[J].Geophysics,2009,74(5):67-76.
[5]Ali Moradi Tehrani,Evert Slob.Applicability of 1D and 2.5D marine controlled source electromagnetic modelling[J].Geophysical Prospecting,2013,S1(61):602-613.
[6]陈光源,杜立彬,景建恩,等.2.5维海洋可控源电磁反演算法及影响参数研究[J].地球物理学进展,2016,31(4):1796-1802.
[7]Unsworth M,Oldenburg D.Subspace inversion of electromagnetic data:application to mid-ocean-ridge exploration[J].Geophys J Int,1995,123(1):161-168.
[8]Mac Gregor L M,Sinha M C,Constable S C.Electrical resistivity structure of the Valu Fa Ridge,Lau Basin,from marine controlled-source electromagnetic sounding[J].Geophysical Journal International,2001,146(1):217-236.
[9]Abubakar A,Habashy T M,Druskin V L,et al.2.5D forward and inverse modeling for interpreting low-frequency electromagnetic measurements[J].Geophysics,2008,73:165-177.
[10]Weitemeyer K,Gao G Z,Constable S,et al.the practical application of 2D inversion to marine controlled-source electromagnetic data[J].Geophysics,2010,75(6):199-211.
[11]Kerry K,Jeffrey O.A parallel goal-oriented adaptive finite element method for 2.5-D electromagnetic modelling[J].Geophys J Int,2011,186(1):137-154.
[12]Yuguo Li,Kerry Key.2D marine controlled-source electromagnetic modeling:Part1—An adaptive finite-element algorithm[J].Geophysics,2007,72(2):51-62.
[13]Kerry Key.MARE2DEM:a 2-D inversion code for controlled-source electromagnetic and magnetotelluric data[J].Geophys J Int,2016,207:571-588.
[14]杨梅霞,张胜业,贾豫葛.海洋大地电磁二维正演及结果分析[J].现代地质,2001,15(1):98-102.
[15]沈金松,孙文博.二维海底地层可控源海洋电磁响应的数值模拟[J].石油勘探,2009,48(2):187-194.
[16]刘颖.海洋可控源电磁法二维有限元正演及反演[D].青岛:中国海洋大学,2014.
[17]Polak E.Computational methods in optimization:A unified approach[M].New York:Academic Press,1971.
[18]Magnus R.Hestenes and Eduard Stiefel.Methods of conjugate gradients for solving linear systems[J].J Research Nat Bur Standards,1952,49:409-436.
[19]Fletcher R,Reeves C.Function minimization by conjugate gradients[J].Comput J,1964,7:149-154.
[20]G H Liu,J Y Han,H D Qi,et al.Convergence analysis on a class of conjugate gradient methods[J].Acta Mathematica Scientia,1998,18(2):11-16.
[21]何继善.海洋电磁法原理[M].北京:高等教育出版社,2012.
[22]Anne M Trehu,Ernst R Flueh.Estimating the thickness of the free gas zone beneath Hydrate Ridge,Oregon continental margin,from seismic velocities and attenuation[J].Journal of Geophysical research,2001,106(B2):2035-2045.
[23]Johanna Chevallier,Anne M Trehu,Nathan L Bangs,et al.Seismic sequences stratigraphy and tectonic evolution of southern hydrate ridge[J].Proceedings of the Ocean Drilling Program,Scientific Results,2006,204:1-29.