1. Introduction

According to forecasts by the IEA (International Energy Agency), the global demand for oil will increase by an average rate of 1.2 million barrels per day (mb/d) through 2021 (IEA 2016), with world demand growing from 94.4 mb/d (2015) to 101.6 mb/d (2021).

In the current state of knowledge, the scenario takes into account a growing demand for electricity, an ecological imperative (reducing greenhouse gas emissions) and a significant decline in oil resources. The nuclear electricity production currently accounts for just 5 % of the energy consumed in the world.

Probably more than a half by 2020.

In 2011, the average price of a barrel of crude oil over the year was $US111. Today the production of oils and shale gas (diffuse deposits) has completely changed the game in economic matters in the energy mondial marketplace and in geophysical prospecting investments. After the consumption of oil slowing down and in an overabundance market, oil has recently seen its price drop below US$30 a barrel, well below its cost price. Worldwide, in 2015, the oil industry lost over a third of its workforce. A number of analysts however already agree that this phenomenon is transient and that the price of oil should in late for the future years return to a more realistic level of around US$100 a barrel. Stay tuned… Last minute: the most recent OPEP agreements on the reduction of oil production, mainly supported by Saudi Arabia, are expected to raise oil prices significantly, or at least stabilize prices around sixty dollars for 2017.

An operation that also requires a huge amount of water.

Much less with the current techniques of horizontal drilling.

“Arctic oil and gas resources represent the next big chapter in offshore development. Yet, the development of these resources remains challenging in terms of engineering, construction and installation, and related logistics” (Kenny 2011). This is also evidenced by the recent exploration agreement (September 6, 2011) between American companies Exxon Mobil and Russian Rosneft. With this contract Russia seems to initiate a serious investment policy. The USGS estimated in 2008 that undiscovered conventional hydrocarbon reserves exceeded 90 billion barrels of oil, 1669 trillion cubic feet of natural gas, and 44 billion barrels of natural liquid gas (Bird et al. 2008).

Shortages in the relatively short term of our energy resources today push nations that have the means to discover new El Dorado mining (oil and gas). This is particularly the case in countries bordering the Arctic Sea (the USA, Canada, Denmark, Norway and Russia), which recently engaged in a “war” of ownership of the seabed with a very clear challenge to the territorial limits of the international maritime domain (a 2001 request by Moscow to the United Nations to claim the arctic seabed followed in 2007 by an exploratory mission with laying of flags on the seabed). This first geographical stage with the opening of the Northwest Passage actually precedes a no less important exploration phase itself, which will intensely begin in this decade. The Arctic Ocean would contain, according to specialists, a quarter of the global oil reserves (on the Russian side, the arctic subsoil would conceal hundred billion tons of oil equivalent).

Marine seismic acquisition represents a cost five times less than that of land acquisition, which requires more important logistical and human resources. However, the boats’ immobilization is more expensive especially in times of economic inactivity (standby).

A magnetic survey (related to volcanic activity) and/or gravimetric survey (linked to salt-bearing diapiric activity) can complete the seismic campaign.

Exploration with well/drilling activities and pipeline transport are the upstream sectors or exploration/production sectors of oil activity (upstream or E & P petroleum sector).

On September 25 and 28, 1945, the US President Harry Truman launched the real policy of development of offshore deposits (Diolé 1951). A few years later (1949), in Azerbaijan, the Soviet government under the leadership of Stalin started oil production in the Caspian Sea (Oil Rocks).

For 5 years, more than 3000 wells per year on average have been drilled offshore, corresponding to a turnover of over $40 billion.

This concept was first formalized in the 1940s (Gabriel 1945).

Such as the accident at the Deepwater Horizon platform in 2010 in the Gulf of Mexico.

Geological studies also follow all stages of the exploration process.

This is called the evaluation phase, which allows through wells seismic and log data among others to define the deposit in terms of its shape and its size. This is known as delineation of the deposit.

The downhole logs include instant logs (logging while drilling, or LWD) executed during drilling with instrumentation located behind the drill bit, and well logs (delayed well logging), performed after drilling with instrumented probes connected to the surface by an electric cable. These measures correspond to microvolumetric investigations into the immediate surroundings of the borehole.

Sediment sounders, whether mechanical or acoustic, can also provide information within certain limits.

A seismic source cannot be deeply submerged. Unless it is otherwise (with an implosive source), it has to fight against the increasing hydrostatic pressure with the water level.

Old treatises on petroleum geology available in university libraries (e.g., Levorsen 1954) are interesting in their naturalistic and historical approach but instead should be read with great caution regarding the interpretations of the geological phenomena including the geodynamics presented there.

See the main treatises on petroleum geology mentioned above.

It may be recalled that the earth is about 4.5 billion years old and that the oil deposits discovered to date cover the period from –500 My to –4000 y.

This is the term used in practice by the oil industry instead of the word “petroleum.”

The reader will find in the book La recherche pétrolière en France an excellent introduction to the origins of oil and a history of the evolution of ideas on the subject (Pelet 1994).

All these physicochemical and biochemical processes lead marine sediments to turn into sedimentary rocks. These transformations (compaction, déshydration, dissolution, cementation, etc.) occur at shallow depths.

Level surface through the vanishing point (the top point of the oil and gas filling).

Geological layer of impermeable rock (marl for example) or less permeable rock (dolomite) that the rock store, located at its apex and whose shape prevents any upward movement of hydrocarbons (migration stop). The main qualities ensuring a good seal are the lithological composition, the degree of homogeneity of the rock, the thickness and the formation distribution mode. The greatest power of containment is provided in general by saliferous layers. Depending on their size, we can distinguish the regional coverings governing petroliferous provinces, the zonal coverings filling up several fields and local coverings in one field.

Briefly, these traps usually come from ground movements related to the tectonics of the sedimentary basins, which are themselves derived from geological phenomena on a larger scale as well as orogeneses, which then cause at more or less large distances foldings, breaks, thrustings, etc. A review in detail would require much discussion. For this reason we invite the reader to consult some books about geodynamics.

We can distinguish the primary stratigraphic traps contemporary to the sedimentation, from the secondary stratigraphic traps posterior to it.

The contribution of gravity and magnetic studies is also used in some favorable situations when the traps are associated with volcanism (lava), for example.

Freshwater in return is resistant.

Applied geophysics is a relatively young science. If we disregard the divining rod (hazel stick) used by dowsers (Agricola 1556), we can trace the first concrete application of physics to the magnetic detection of minerals in the early seventeenth century (Gilbert 1628). But it was probably with the torsion balance (gravity) of the Hungarian scholar Eötvös (1898) and with the electrical methods of the Electrical Ore Finding Company Ltd (1902) and then of the Frenchman Conrad Schlumberger (1912) that geophysics entered the industrial era. In 1933, offshore exploration began in the Gulf of Mexico (USA) some time after the investigations of Lake Maracaibo (Venezuela) and of the Caspian Sea off Baku (Azerbaijan). At that time it was done to recognize the extension of onshore fields. It was in 1947 that the first subsea well was actually put into production (see note 13). A brief history can be reconstructed by consulting Appendix A1.1 and specifically the following books: Allaud and Martin (1976), Anonyme (1983), Castel D du et al. (1995), Collectif (1966), Iakanov (1957), Kertz and Glassmeier (1999), Sweet (1969), Virchow et al. (1999), Walter et al. (1985) and Ward (1952).

We then go back to the concept of the geologist who, from his observations on the ground (surface), imagines, by his knowledge of the genesis of the deposits, the arrangement of the different grounds of the subsoil.

A greater ambition of indirect exploration, but more difficult to satisfy, is to date the marker horizons allowing establishment of a certain chronology.

Translated from Russian…

This is for example the case of the Barret Company Inc., which suggested in the 1950s a radioelectrical method (the Radoil method), working in the band of 100 kHz to 500 kHz (Barret 1947, 1949). This controlled source terrestrial technique enabled, by measuring the intensity of the reflected waves in the subsoil, detection of the presence or absence of anomalies of conductivity in depth and thus marked the difference between the salt water, the hydrocarbons and the rock. Use of radio waves more directive indeed than those related to low frequency (and continuous) currents could then make apparent some accurate phenomena of reflection/refraction as observed in seismic prospection (Melton 1933). But it did not take into account the low penetration of energy related to the high frequency used, and the theoretical difficulty, if any (a very important skin effect), which was bypassed straightforwardly by the developers of the method by announcing the existence of selective absorption zones in certain frequency bands (unproven) then favouring penetration at great depth. Furthermore, to overcome significant dissipative effects due to the ground surface, this company devised a transmitter able to generate a surface wave, which, while flowing over it, could chip, thereby forming a number of secondary sources up to the receivers causing a cumulative effect on receiving. Another interesting case was that of the Sorge Company, whose approach at low and very low frequencies was somewhat different and more plausible in its conceptual approach (Calvaresi, 1954, 1957).

The surface signs were at the base of the first oil onshore discoveries in the mid-nineteenth century (Titusville, Bakou, Grozny, Mossoul, Pechelbron). Today, oil companies try to develop observation submarine devices (ROVs, AUVs equipped with thermal cameras) for physical signs (gas bubbles or droplets of oil escaping from the sediments). What did we know in 1900 about the nature of underwater rocks? Virtually nothing. The engineers had a good idea about the variations in the oceanic relief thanks to the works of laying trans-Atlantic telegraph cables (in the nineteenth century), but had no more information because of the absence of effective means of investigation of the soil and even less sea subsoil exploration at great depth (Delesse 1872; Murray and Renard 1891; Renaud 1902; Termier 1951; Whittar et Bradshaw 1965).

The resistivity contrast between the reservoir and the marine sediments is more important than the contrast of acoustic impedances encountered in seismic exploration.

Very briefly, the electric logs allow understanding of a very precise diagnosis of permeable layers. In particular, we can derive information on:

“Resistivity is important because oil is insulating and water is conductive, so there is something natural, deep: it is truly the measure which is needed to identify the oil.” Jean-Pierre Causse (Dorozynski and Oristaglio 2007).

Magnetic studies (in the volcanic context) and especially gravimetric studies (in the context of saliferous tectonics) may also be in keeping with this phase.

Recording of the measurements of physical properties of rocks in relation to depth.

We owe this original technique to the Frenchman Conrad Schlumberger, who applied it as far back as 1912 (Schlumberger 1920a, b). Magnetic prospection is the oldest of all the geophysical methods applied with discernment. However it only affects magnetic and ferromagnetic materials. In 1640, the Swedes tried to find iron mines with compasses. But it was only after 1870 (Brocke in 1873 in the USA and Thalen in 1876 in Sweden) that we clearly realized the disruptive effect of magnetic masses in the earth’s magnetic field.

In 1927, Conrad Schlumberger expanded his surface concept to the well by the electrical logging technique known today more commonly as logs (Schlumberger 1927).

Société de Prospection Electrique, Procédés Schlumberger and Compagnie Générale de Géophysique.

One could compare the beginnings of seabed logging to the birth of wireless telegraphy where Marconi had the intuition to bring together into a single concept Maxwell’s (theory) and Hertz’s discoveries (experience), and Popov’s (the antenna), Ruhmkorff’s (power transmitter) and Branly’s inventions (detector: coheror), to make a remarkable communication tool with the commercial success that everyone knows.

The idea of using the electrical properties of (nonmagnetic) metallic minerals dates from the nineteenth century (Fox 1830). From that time, researchers have suggested studying the distribution of the electromagnetic fields using high frequency devices (Leimbach and Löwy 1910), low frequency processes (Daft and William 1902) or measurements from DC injection with electrodes planted in the ground (Brown 1903; Mc Clatchey 1900). The first serious investigations began before the First World War (Schlumberger 1912; Wenner 1914) to take, from the 1920s, an economic boom with the creation of societies exclusively devoted to this particular technique of direct prospection (Hedstrom 1930). Only the use of direct current (or pulses) was recommended and able to quickly force itself until today. On land, it has the main advantage of virtually controlling the depth of investigation and theoretically increasing it to infinity (never achieved in practice), but has the main drawback of integrating an excessive volume of land, which does not allow any lateral resolution. This therefore confines the DC method only to an investigation in depth of horizontal geological strata in an often limited number (three or four maximum), and applicable only in some domains of subsurface applied geophysics. “It’s certainly by electrical methods that have been obtained, 40 years ago, the first indisputable successes of geophysical prospecting” (Cagniard 1953a, b).

Interesting results had already been obtained in several surveys in marshy ground and in the bayous of Louisiana, where the electrodes were then planted in the ground.

Also written as “Bibi Heybat”—the first oil field reclaimed from the sea south of the Bay of Baku whose remains today show disrepair where pipes and wells are leaking from everywhere.

At that time there was also initiation of the first experiments of underwater detection, of study of the seaboard effect, etc., where specific and confidential materials (magnetic variometers) were developed (Mosnier 1986).

The system used then was relatively sophisticated: current sendings every 15, 30 and 60 s by a fixed dipole and acquisition when the steady state was established on a mobile dipole. The measures of the current at emission and the voltage at receiving were connected by a radioelectrical telemetry device taking account of the speed of relative movement of the two dipoles and of their spacing. We can say that these early experiences prefigured the current methods (reverse SBL).

Extremely low frequency (see Chap. 4 Sect. 3).

Very low frequency. Frequency band used in the submarine telecommunications.

The reader will find a comprehensive history of modern development of the methods in the article by Professors Constable and Snrka on mCSEM (Constable and Snrka 2007).

A horizontal electromagnetic dipole.

The world’s largest Marine Research Institute involving several university laboratories, private and military (US Navy).

The reader will find in this last article a comprehensive summary of this epic and a very concise summary of the SBL technique, especially applying to the uninitiated.

The authorship of these innovations is currently hotly debated. The industrial stakes are high, and several trials are ongoing (see Chap. 2, Footnote 47).

Experience at Waterloo Bridge (Faraday 1832). After laying two copper plates connected to a sensitive galvanometer in the Thames, a short distance from the banks of the river, the English scholar noted in the circuit the forming of a small electric current. The explanation for this phenomenon of induction (a moving conductor in a magnetic field) would be given a few decades later by Lorentz (see Chap. 3 Sect. 6.​9.​2).

Previously, after the introduction of total field magnetometers in the 1960s (proton or optical pumping magnetometers), sensitive magnetic variometers appeared in the 1970s. These ones (declinometer, H meter and Z meter) offered the possibility of simultaneously measuring the two components of the field (Mosnier 1977).

This comes from the Melos process, a magneto-electric method using a surface wave, developed in particular by the Bureau de Recherches Géologiques et Minières (Duroux 1967).

This is also the case in mineral exploration for the detection of conductive masses.

For example, the low frequency inductive methods (the methods of the spiral or hoop developed by the SPE in the 1930s) for measuring the dips of deep geological structures (an indirect method), or the high frequency methods (radio waves) using the phenomena of reflection and refraction (or absorption) of the waves on the roof of hydrocarbon reservoirs (a direct method). With a lack of conclusive results, these technics proposed by virtually all companies at that time (1930–1950) were quickly abandoned in favor of seismics (an indirect method).

The electrotelluric method developed in the 1930s by the SPE and implemented in France in 1940 by CGG had great success after the war in Europe and North Africa with the discoveries, among others, of the deposits of Saint Marcet (France) and Hassi Messaoud (Algeria). Lack of a sufficient market (especially absent in the USA) and with more restrictive conditions than seismic reflection, which asserted itself more and more, the electrotelluric method was gradually abandoned despite a revival and development in the Soviet Union.

This method, where we simultaneously measure the variations of the electric and magnetic fields, should rather be called the electromagnetotelluric method.

Meanwhile geomagnetic soundings were completed (Barsczus 1970).

For a sufficient resistivity contrast.

Rather variable turnover, very sensitive to economic conditions.

With a wide disparity between the different companies ($140 million for EMGS in 2007) and a significant decline in recent years (2009–2010).

Exxon/Mobil, Shell, BP and Total.

Currently in a joint venture with the operator Fugro.

Probably the most advanced company in this sector.

First job in 2006.

See detailed calculations in the Appendix A3.2.

Note that these animals for their orientation are a priori sensitive to changes in continuous magnetic fields (the earth field) or over very long periods (telluric currents). At the present day, the currents used in SBL vary in a frequency band from 0.25 Hz to 10 Hz, which logically should not affect these animals.