Characteristics of simulated marine controlled-source electromagnetic responses of coupled gas hydrate and petroleum reservoir models
GAO Yan1,2, MA Chao1,2,3, ZHANG Xiangyu1
1.Guangzhou Marine Geological Survey, Guangzhou, Guangdong 511458, China; 2.Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou, Guangdong 511458, China; 3.National Engineering Research Center of Gas Hydrate Exploration and Development, Guangzhou, Guangdong 511458, China
Abstract:Marine controlled-source electromagnetic method (MCSEM) can be employed to identify resistivity anomalies on the seafloor and is thus widely used in offshore petroleum exploration. A simulation method of frequency-domain vector finite-element electromagnetic forward modeling based on preconditioned iterative solution is proposed on the basis of a complex seafloor strata model with a complex electrical structure. The preconditioning method based on incomplete lower-upper (ILU) decomposition improves the efficiency of iterative solution. The simulation results of the layered model verify the effectiveness of the method. A geoelectric model of a certain area of the South China Sea is built with arbitrary hexahedral structured elements. A deep-buried petroleum reservoir model,a gas hydrate deposit model,and a geological model with a complex basement are built,respectively,according to the reservoir characteristics of deposits with different structures. The characteristics of MCSEM response are analyzed under different excitation-receiving modes. Specifically,when the offset is small,the influence of topography is obvious. The influence is especially salient on shallow-buried gas hydrate deposits when the offset is small,while it is more distinct on deep-buried petroleum reservoirs when the offset is large.
柳建新,郭天宇,王博琛,等. 油气勘探中海洋电磁技术的研究进展[J]. 石油物探,2021,60(4):527-538.LIU Jianxin,GUO Tianyu,WANG Bochen,et al. Review of marine electromagnetic methods for hydrocarbon exploration[J]. Geophysical Prospecting for Petroleum,2021,60(4):527-538.
[2]
刘勇,李文彬,邓方顺,等. 海洋可控源电磁法深海油藏开采监测仿真[J]. 石油地球物理勘探,2022,57(1):237-244.LIU Yong,LI Wenbin,DENG Fangshun,et al. Simulation of deep-sea reservoir development monitoring using marine controlled-source electromagnetic me-thod[J]. Oil Geophysical Prospecting,2022,57(1):237-244.
[3]
ANDRÉIS D,MACGREGOR L. Controlled-source electromagnetic sounding in shallow water:principles and applications[J]. Geophysics,2008,73(1):F21-F32.
[4]
CONSTABLE S,SRNKA L J. An introduction to marine controlled-source electromagnetic methods for hydrocarbon exploration[J]. Geophysics,2007,72(2):WA3-WA12.
[5]
SRNKA L J,CARAZZONE J J,EPHRON M S,et al. Remote reservoir resistivity mapping[J]. The Leading Edge,2006,25(8):972-975.
[6]
UM E S,HARRIS J M,ALUMBAUGH D L. An ite-rative finite element time-domain method for simulating three-dimensional electromagnetic diffusion in earth[J]. Geophysical Journal International,2012,190(2):871-886.
[7]
ZHDANOV M S. Electromagnetic geophysics:notes from the past and the road ahead[J]. Geophysics,2010,75(5):75A49-75A66.
[8]
裴发根,方慧,裴亮,等. 天然气水合物电磁勘探研究进展[J]. 地球物理学进展,2020,35(2):775-785.PEI Fagen,FANG Hui,PEI Liang,et al. Advances in electromagnetic exploration research of gas hydrate[J]. Progress in Geophysics,2020,35(2):775-785.
[9]
景建恩,伍忠良,邓明,等. 南海天然气水合物远景区海洋可控源电磁探测试验[J]. 地球物理学报,2016,59(7):2564-2572.JING Jian’en,WU Zhongliang,DENG Ming,et al. Experiment of marine controlled-source electromagnetic detection in a gas hydrate prospective region of the South China Sea[J]. Chinese Journal of Geophy-sics,2016,59(7):2564-2572.
[10]
DA SILVA N V,MORGAN J V,MACGREGOR L,et al. A finite element multifrontal method for 3D CSEM modeling in the frequency domain[J]. Geophysics,2012,77(2):E101-E115.
[11]
杨军,刘颖,吴小平. 海洋可控源电磁三维非结构矢量有限元数值模拟[J]. 地球物理学报,2015,58(8):2827-2838.YANG Jun,LIU Ying,WU Xiaoping. 3D simulation of Marine CSEM using vector finite element method on unstructured grids[J]. Chinese Journal of Geophysics,2015,58(8):2827-2838.
[12]
殷长春,贲放,刘云鹤,等. 三维任意各向异性介质中海洋可控源电磁法正演研究[J]. 地球物理学报,2014,57(12):4110-4122.YIN Changchun,BEN Fang,LIU Yunhe,et al. MCSEM 3D modeling for arbitrarily anisotropic media[J]. Chinese Journal of Geophysics,2014,57(12):4110-4122.
[13]
周峰,张志勇,陈煌,等. 基于非结构网格的三种CSEM有限元三维正演系统分析[J]. 石油地球物理勘探,2021,56(5):1190-1202.ZHOU Feng,ZHANG Zhiyong,CHEN Huang,et al. Analysis of 3D finite-element forward modeling of CSEM data using three different formulas and unstructured grids[J]. Oil Geophysical Prospecting,2021,56(5):1190-1202.
[14]
KOLDAN J,PUZYREV V,DE LA PUENTE J,et al. Algebraic multigrid preconditioning within parallel finite-element solvers for 3-D electromagnetic modelling problems in geophysics[J]. Geophysical Journal International,2014,197(3):1442-1458.
[15]
LELIÈVRE P G,FARQUHARSON C G. Gradient and smoothness regularization operators for geophysical inversion on unstructured meshes[J]. Geophysical Journal International,2013,195(1):330-341.
[16]
MITSUHATA Y,UCHIDA T. 3D magnetotelluric modeling using the T-Ω finite element method[J]. Geophysics,2004,69(1):108-119.
[17]
SCHWARZBACH C,BÖRNER R U,SPITZER K. Three-dimensional adaptive higher order finite element simulation for geo-electromagnetics:a marine CSEM example[J]. Geophysical Journal International,2011,187(1):63-74.
[18]
SCHWARZBACH C,HABER E. Finite element based inversion for time-harmonic electromagnetic problems[J]. Geophysical Journal International,2013,193(2):615-634.
[19]
NAM M J,KIM H J,SONG Y,et al. Three-dimensional topographic and bathymetric effects on magnetotelluric responses in Jeju Island,Korea[J]. Geophysical Journal International,2009,176(2):457-466.
[20]
CAI H Z,XIONG B,HAN M R,et al. 3D controlled-source electromagnetic modeling in anisotropic medium using edge-based finite element method[J]. Computers & Geosciences,2014,73:164-176.
[21]
BADEA E A,EVERETT M E,NEWMAN G A,et al. Finite-element analysis of controlled-source electromagnetic induction using Coulomb-gauged potentials[J]. Geophysics,2001,66(3):786-799.
[22]
KEY K,WEISS C. Adaptive finite-element modeling using unstructured grids:the 2D magnetotelluric example[J]. Geophysics,2006,71(6):G291-G299.
[23]
LI Y G,KEY K. 2D marine controlled-source electromagnetic modeling:part 1-an adaptive finite-element algorithm[J]. Geophysics,2007,72(2):WA51-WA62.
[24]
MUKHERJEE S,EVERETT M E. 3D controlled-source electromagnetic edge-based finite element mo-deling of conductive and permeable heterogeneities[J]. Geophysics,2011,76(4):F215-F226.
[25]
NAM M J,KIM H J,SONG Y,et al. 3D magnetotelluric modelling including surface topography[J]. Geo-physical Prospecting,2007,55(2):277-287.
[26]
KORDY M,WANNAMAKER P,MARIS V,et al. 3D magnetotelluric inversion including topography using deformed hexahedral edge finite elements and direct solvers parallelized on SMP computers-part Ⅰ:forward problem and parameter Jacobians[J]. Geophysical Journal International,2015,204(1):74-93.
[27]
GU X M,HUANG T Z,LI L,et al. Quasi-minimal residual variants of the COCG and COCR methods for complex symmetric linear systems in electromagnetic simulations[J]. IEEE Transactions on Microwave Theory and Techniques,2014,62(12):2859-2867.
[28]
LI L,HUANG T Z,JING Y F,et al. Application of the incomplete Cholesky factorization preconditioned Krylov subspace method to the vector finite element method for 3-D electromagnetic scattering problems[J]. Computer Physics Communications,2010,181(2):271-276.
[29]
UM E S,COMMER M,NEWMAN G A. Efficient pre-conditioned iterative solution strategies for the electromagnetic diffusion in the Earth:finite-element frequency-domain approach[J]. Geophysical Journal International,2013,193(3):1460-1473.
[30]
BÖRNER R U. Numerical modelling in geo-electromagnetics:advances and challenges[J]. Surveys in Geophysics,2010,31(2):225-245.
[31]
尚晓荣,岳明鑫,杨晓冬,等. 起伏地形对三维可控源电磁响应的影响研究[J]. 石油地球物理勘探,2022,57(1):222-236.SHANG Xiaorong,YUE Mingxin,YANG Xiaodong,et al. Influence of undulating terrain on three-dimensional controlled-source electromagnetic response[J]. Oil Geophysical Prospecting,2022,57(1):222-236.
[32]
沈金松,陈小宏. 海洋油气勘探中可控源电磁探测法(CSEM)的发展与启示[J]. 石油地球物理勘探,2009,44(1):119-127.SHEN Jinsong,CHEN Xiaohong. Development and enlightenment of controlled-source electromagnetic (CSEM) surveying method in marine oil/gas exploration[J]. Oil Geophysical Prospecting,2009,44(1):119-127.
[33]
任文静,何展翔,孙卫斌,等. 海底节点式时频双域电磁采集系统及试验[J]. 石油地球物理勘探,2021,56(2):398-406.REN Wenjing,HE Zhanxiang,SUN Weibin,et al. Benthic nodal time-frequency dual-domain electromagnetic acquisition system and test[J]. Oil Geophysical Prospecting,2021,56(2):398-406.