The Arctic Needs New Subsea Seismic Technologies

The participation of onshore exploration experts in the offshore conference was not a happenstance: four years ago, GEOTECH Holding specialists floated the idea of developing subsea exploration vessels (N.V. Levitsky, V.A. Detkov, G.Y. Shaidurov, 2010). They proposed using the pulsed electromagnetic sources Enisey to produce seismic waves during subsea surveys. At the moment, such sources are being successfully applied in seismic surveys in rivers in Eastern Siberia. This Russian technology was developed in the late 80s with the participation of researchers and designers from academic institutes. The technology is based on the electromagnetic principle of a Gauss gun. The device is a short-stroke electromagnetic motor that converts electromagnetic field energy into the seismic waves. Pulsed sources are widely used by Russian seismic companies, as well as foreign companies (Iran, USA, Kazakhstan). In 2010-2013, the technology was significantly upgraded during an integrated project in cooperation with scientists of the Siberian Federal University and with the support of the Ministry of Education and Science of the Russian Federation. Namely, the offshore model of pulsed sources was modified. Actually universal pulsed sources were developed. They generate elastic waves on land, ice, and under water. 

Practical experience shows that such an induction of oscillations in the soil through water is the most environmentally safe in comparison with alternative sparker sources, pneumatic guns that cause irreparable damage to aquatic life. An electromagnetic drive is designed so that impact is made by a flat antenna that uses the backstroke principle, which allows one to concentrate all energy in the low-frequency elastic oscillation and avoid shock waves, inelastic stains which in other cases directly damage hydrobionts. 

Enisey modules in compact groups produce only an elastic wave in water. The wave travels through water with minimum impact on fish and plankton. Additionally, electromagnetic seismic wave sources are simple in design, they are field-repairable, and they are also substantially more efficient than other non-explosive sources with a comparable seismic energy.

 The danger posed by ice traps was in full display during the recent accident with the ice breaker Akademik Shokalskiy in Antarctica. Ice conditions in the oil bearing regions of the Arctic shelf, such as the Kara Sea, are far from better. This was the reason behind our call for a a large-scale integrated project to create and develop Russian technologies for Arctic offshore field development and exploration. Such technologies should primarily focus on under-ice application: under-ice drill rigs, subsea stations, giant diving tankers, submarines for the exploration and protection of facilities. In the above interview, D.O. Rogozin mentioned the advanced underwater technologies that are intended for application in hydrocarbon exploration and production in the Arctic shelf. However, at the meeting at the Advanced Research Foundation, in their presentation the Rubin Design Bureau stressed that neither Russia nor any other countries possessed underwater exploration vessels. That was the reason why GEOTECH’s proposals to equip submersible vehicles with pulsed electromagnetic sources of seismic waves was understood by the participants. 

 The pulsed seismic sources Enisey have been successfully applied on water surfaces since 2004 (P.Y.Schadin, V.A. Bogdan, 2010). However, it is almost impossible to apply towed technical aids for transmitting and receiving seismic signals in Arctic conditions as the sea surface is covered with ice almost all year. For the propagation of seismic waves, it does not matter wh ere the source is located - on the water surface or under water. That is why the impossibility of seismic acquisition from the water surface dictates the need for the development of submerged seismic acquisition technologies. The creation of such technology will require both the development of completely new technical solutions and upgrading of existing equipment for the specific conditions of underwater operations. An atomic submarine as a base research vessel is the most suitable vehicle for underwater operations. It can operate under ice for a prolonged period of time and has a high-quality noise suppression system (N.V. Levitsky, V.A. Detkov, 2010). Manned and unmanned submersibles most likely should be used as support research vessels. Several schemes of arrangement of seismic sources and receivers are possible in case of underwater seismic acquisition. In all cases, the source station comprising an upgraded electromagnetic pulsed source Enisey should be placed under the bottom of a submarine. In an extreme case, it is possible to tow a submerged pulsed source however technically that might be more complicated. There are more options for the arrangement of receivers. 

Firstly, receivers can be placed on the ice surface. At first glance, such an option would appear the easiest one. However, such an arrangement of source-receivers will be a combined submerged-surface scheme which requires a combined application of submerged and surface equipment. In addition, there is the problem of the seasonal character of operations, which can be conducted only in winter.

Secondly, receivers can be designed as towed seismic cables stabilized at a certain depth. Although this option is more technically challenging, it allows one to maximize productivity in seismic surveys with all-year-round operations. 

Thirdly, receivers can be installed on the sea bed. On the one hand, this would significantly compromise productivity even with all-year-round operations. But on the other hand, it would allow for the use of already existing underwater recorders. Evidently, implementation of underwater seismic acquisition technologies will require integrated R&D efforts both in the development of the equipment and in the development of methods for underwater seismic surveys. Despite the apparent complexity of a practical implementation of the proposed technology, there is no doubt that it can be implemented. To put it bluntly, the issue of developing Arctic offshore resources leaves us with no other choice but to develop a Russian technology for the geological and geophysical exploration and production of minerals in this region.

1. N. V. Levitsky, V. A. Detkov. Technology of Seismic Exploration in Deep Water Areas of the Arctic Ocean //Seismic Exploration Technologies. No. 3, 2010, page 104 

2. Shchadin P.Yu., Bogdan V.A. Pulsed Sources Enisey-VEM for Water Areas and Transit Zones.//Exploration Geophysics Devices and Systems. 2010. No. 2. Pages 42–48.