Petroleum exploration using controlled-source electromagnetic methods

A tutorial overview is presented of controlled-source electromagnetic (CSEM) geophysical methods as they are applied in petroleum exploration. CSEM methods utilize man-made sources to investigate the variation of electrical conductivity in the Earth, typically in the depth range of hundreds of meters to several kilometers. Over the frequency range used in CSEM (typically 0.1 Hz to 10 KHz), displacement currents can usually be ignored so the EM fields are diffusive in nature. The basic theory for CSEM methods and some simple approximate solutions which provide insight into the behavior of quasistatic EM fields are given. An overview of data inversion methods is also given, as well as examples of typical applications. It is argued that CSEM methods offer a number of advantages compared to natural-source electromagnetic (NSEM) methods such as magnetotellurics (MT). These include relative insensitivity to regional effects and small near-surface inhomogeneities which adversely affect MT, and the ability to utilize different source types and orientations to improve resolution. NSEM methods can, however, probe deeper conductivity structures than CSEM methods. >

[1]  Gregory A. Newman,et al.  Interpretation of transient electromagnetic soundings over three-dimensional structures for the central-loop configuration , 1987 .

[2]  Lithologically discordant resistivity and IP anomalies associated with hydrocarbons in the Rocky Mountain foothills of Alberta Canada , 1987 .

[3]  Misac N. Nabighian,et al.  Time-domain electromagnetic methods of exploration; foreword and introduction , 1984 .

[4]  R. Parker.  The Fréchet derivative for the one-dimensional electromagnetic induction problem , 1977 .

[5]  Douglas W. Oldenburg,et al.  Inversion of horizontal loop electromagnetic frequency soundings , 1984 .

[6]  M. Nabighian.  Quasi-static transient response of a conducting half-space; an approximate representation , 1979 .

[7]  Alan G. Jones,et al.  Static shift of magnetotelluric data and its removal in a sedimentary basin environment , 1988 .

[8]  R. Young,et al.  Exploration beneath volcanics: Snake River plain, Idaho , 1988 .

[9]  M. Oristaglio,et al.  INVERSION OF SURFACE AND BOREHOLE ELECTROMAGNETIC DATA FOR TWO‐DIMENSIONAL ELECTRICAL CONDUCTIVITY MODELS* , 1980 .

[10]  Alan C. Tripp,et al.  Two-dimensional resistivity inversion , 1984 .

[11]  H. Vinegar,et al.  Induced polarization of shaly sands , 1984 .

[12]  A. Howard,et al.  Synthesis of EM geophysical tomographic data , 1986, Proceedings of the IEEE.

[13]  J. T. Weaver,et al.  H-polarization induction over an ocean edge coupled to the mantle by a conducting crust , 1977 .

[14]  G. Buselli,et al.  SIROTEM: A New Portable Instrument for Multichannel Transient Electromagnetic Measurements , 1977 .

[15]  Brian R. Spies,et al.  The use and misuse of apparent resistivity in electromagnetic methods , 1986 .

[16]  David D. Jackson,et al.  A Bayesian approach to nonlinear inversion , 1985 .

[17]  Ki Ha Lee,et al.  Electromagnetic Sounding In the Columbia Basin, Yakima, Washington , 1988 .

[18]  J. H. Moran,et al.  Effects of formation anisotropy on resistivity‐logging measurements , 1979 .

[19]  James R. Wait,et al.  EM AND IP RESPONSE OF A STEEL WELL CASING FOR A FOUR-ELECTRODE SURFACE ARRAY. PART I: THEORY* , 1985 .

[20]  B. Spies.  A FIELD OCCURRENCE OF SIGN REVERSALS WITH THE TRANSIENT ELECTROMAGNETIC METHOD , 1980 .

[21]  K. G. McCracken,et al.  A comparison of electromagnetic exploration systems , 1986 .

[22]  Brian R. Spies,et al.  Local noise prediction filtering for central induction transient electromagnetic sounding , 1988 .

[23]  T. Madden,et al.  Generalized thin sheet analysis in magnetotellurics: an extension of Price's analysis , 1980 .

[24]  Mapping Gas-Water Contacts In Shallow Producing Formations With Transient EM , 1983 .

[25]  G. Backus,et al.  The Resolving Power of Gross Earth Data , 1968 .

[26]  Arnold Orange,et al.  Effects of three-dimensional structure on magnetotelluric sounding curves , 1983 .

[27]  R. Parker,et al.  Occam's inversion; a practical algorithm for generating smooth models from electromagnetic sounding data , 1987 .

[28]  D. Oehler,et al.  Seepage-induced anomalies, false anomalies, and implications for electrical prospecting , 1984 .

[29]  Daniel H. Rothman,et al.  Nonlinear inversion, statistical mechanics, and residual statics estimation , 1985 .

[30]  Gerald W. Hohmann,et al.  Controlled‐source audiomagnetotellurics in geothermal exploration , 1980 .

[31]  Joseph Robert Inman,et al.  RESISTIVITY INVERSION WITH RIDGE REGRESSION , 1975 .

[32]  P. Fullagar.  A uniqueness theorem for horizontal loop electromagnetic frequency soundings , 1984 .

[33]  R. L. Mackie,et al.  Three-dimensional magnetotelluric modelling and inversion , 1989, Proc. IEEE.

[34]  A. Devaney.  Geophysical Diffraction Tomography , 1984, IEEE Transactions on Geoscience and Remote Sensing.

[35]  R. Parker.  The inverse problem of electromagnetic induction: Existence and construction of solutions based on incomplete data , 1980 .

[36]  John R. Booker,et al.  Electromagnetic Induction Studies , 1987 .

[37]  G. Hoversten,et al.  Transient fields of a current loop source above a layered earth , 1982 .

[38]  A. Orange,et al.  Magnetotelluric exploration for hydrocarbons , 1989, Proc. IEEE.

[39]  Gregory A. Newman,et al.  Transient electromagnetic response of a three-dimensional body in a layered earth , 1986 .

[40]  Alan D. Chave,et al.  Controlled electromagnetic sources for measuring electrical conductivity beneath the oceans: 1. Forward problem and model study , 1982 .

[41]  G. Buselli,et al.  The effect of near-surface superparamagnetic material on electromagnetic measurements , 1982 .

[42]  Stanley H. Ward,et al.  Statistical evaluation of electrical sounding methods; Part I, Experiment design , 1976 .

[43]  Walter L. Anderson,et al.  Computer program; numerical integration of related Hankel transforms of orders O and 1 by adaptive digital filtering , 1979 .

[44]  Effects of pipelines on spectral induced-polarization surveys , 1984 .

[45]  J. Clarke,et al.  REMOTE-REFERENCE MAGNETOTELLURICS: EQUIPMENT AND PROCEDURES* , 1983 .

[46]  S. Ward,et al.  Linear System Description of the Electrical Parameters of Rocks , 1970 .

[47]  R. Parker.  Understanding Inverse Theory , 1977 .

[48]  Brian R. Spies,et al.  Recent developments in the use of surface electrical methods for oil and gas exploration in the Soviet Union , 1983 .

[49]  Louise Pellerin,et al.  Correction for the static shift in magnetotellurics using transient electromagnetic soundings , 1988 .

[50]  F. X. Bostick,et al.  Electromagnetic Array Profiling (EMAP) , 1986 .

[51]  C. S. Cox,et al.  Controlled-source electromagnetic sounding of the oceanic lithosphere , 1986, Nature.

[52]  A. Raiche.  Negative transient voltage and magnetic field responses for a half-space with a Cole-Cole impedance , 1983 .

[53]  D. Jackson,et al.  Detection of tectonomagnetic events using multichannel predictive filtering , 1981 .

[54]  Alan D. Chave,et al.  On the theory of sea-floor conductivity mapping using transient electromagnetic systems , 1987 .

[55]  James Macnae,et al.  Imaging quasi-layered conductive structures by simple processing of transient electromagnetic data , 1987 .

[56]  T. Lee.  THE EFFECT OF A SUPERPARAMAGNETIC LAYER ON THE TRANSIENT ELECTROMAGNETIC RESPONSE OF A GROUND , 1984 .

[57]  H. F. Morrison,et al.  Experience with the EM-60 electromagnetic system for geothermal exploration in Nevada , 1983 .

[58]  J. Heikka,et al.  Preliminary results of MHD test registrations in northern Finland , 1984 .

[59]  James Macnae,et al.  A time‐domain EM system measuring the step response of the ground , 1984 .

[60]  P.R. Bannister.  Summary of image theory expressions for the quasi-static fields of antennas at or above the earth's surface , 1979, Proceedings of the IEEE.

[61]  G. W. Hohmann,et al.  An investigation of finite-element modeling for electrical and electromagnetic data in three dimensions , 1981 .

[62]  W. R. Sill,et al.  Electrical properties of artificial clay-bearing sandstone , 1982 .

[63]  G. W. Hohmann.  Three-Dimensional Induced Polarization and Electromagnetic Modeling , 1975 .

[64]  Gordon F. West,et al.  Effect of well casings on surface electrical surveys , 1984 .

[65]  R. N. Edwards,et al.  First results of the MOSES experiment: Sea sediment conductivity and thickness determination, Bute Inlet, British Columbia, by magnetometric offshore electrical sounding , 1985 .

[66]  Enrique Gómez-Treviño,et al.  Electromagnetic soundings in the sedimentary basin of southern Ontario—A case history , 1983 .

[67]  Gerald W. Hohmann,et al.  Computer simulation of low-frequency electromagnetic data acquisition , 1982 .

[68]  A. G. Nekut,et al.  Direct inversion of time-domain electromagnetic data , 1987 .

[69]  M. Smith.  Permafrost in the Mackenzie Delta, Northwest Territories , 1976 .

[70]  M. S. King.  Acoustic velocities and electrical properties of frozen sandstones and shales , 1977 .

[71]  Stanley H. Ward,et al.  Electrical, electromagnetic, and magnetotelluric methods , 1980 .