Exploración de Hidrocarburos
Con un rango de profundidad de investigación de decenas de metros a decenas de kilómetros, la magnetotelúrica (MT) es un método electromagnético muy apropiado para la prospección de hidrocarburos, que es especialmente más eficaz cuando se utiliza junto con las otras técnicas de exploración geofísica profunda, como la sísmica, los metodos potenciales y TDEM. Nord-West ha llevado a cabo con éxito una serie de grandes proyectos de MT destinados a la exploración de hidrocarburos en todas partes del mundo, a continuación se indican unos de los cuales.
El método magnetotelúrico se ha desarrollado desde la década de 1960 como una herramienta de la investigación de las cuencas sedimentarias [Berdichevsky, 1960, 1968; Keller, 1968; Vozoff, 1972]. Al mismo tiempo, los métodos sísmicos se consideran tradicionalmente como el principal instrumento en la prospección y exploración de hidrocarburos y, en la mayoría de los casos, las tecnologías sísmicas avanzadas permiten resolver las tareas de definición de estructuras y/o formaciones geológicas. Sin embargo, hay varios escenarios geológicos donde los métodos sísmicos enfrentan las dificultades serias, mientras que la aplicación MT puede aumentar significamente la fiabilidad de la interpretación geológica de los datos.
Las formaciones geológicas favorables para MT son las cuencas sedimentarias cubiertas con una gruesa capa de basalto o permafrost. Como ejemplos pueden servir las trampas siberianas en Rusia, la cuenca del Paraná en Brasil [Palshin et al., 2017], así como las cuencas sedimentarias cubiertas por basaltos de Deccan en India. Además, MT es uno de los métodos complementarios y eficientes de prospección de hidrocarburos en las cuencas sedimentarias intracratónicas del Mar del Norte y en las zonas de cabalgamiento, como Zagros en Irán, el cinturón plegado Subandino en Perú y Bolivia o la Depresión Yenisei-Khatanga en Siberia. Otro tipo de cuencas sedimentarias donde MT es muy eficaz está asociado con la tectónica de domo de sal [p.ej. Aleksanova et al., 2009]. Los diapiros de sal se encuentran en muchas cuencas sedimentarias que tienen unos depósitos de sal cubiertos por las formaciones con un espesor bastante grande, así como en las áreas de cinturones plegados. Los diapiros de sal clásicos (domes) se forman debido a la inestabilidad gravitacional en las regiones que no han sufrido un estrés tectónico significativo; sin embargo, algunos domos de sal se encuentran en las regiones tectónicamente activas. El primer tipo se encuentra en las áreas de tectónica de sal en el Golfo de México, el norte de Europa continental, el Mar del Norte y la depresión del Caspio, mientras que los diapiros de sal de Oriente Medio, que se encuentran en Irak, Irán y la Península Arábiga, pertenecen al segundo tipo.
La magnetotelúrica tiene ciertas ventajas en cuando se aplica para mapear la estructura en las zonas plegadas, donde los límites geológicos se caracterizan por los ángulos grandes de buzamiento, lo que también dificulta la interpretación de los datos sísmicos. Los cinturones plegados de Subandian, Taimyr, Zagros, Sinú de Colombia, son unos de los ejemplos de las áreas plegadas con el petróleo y gas prometedor [Palshin et al., 2021]. La conductividad eléctrica de las rocas sedimentarias depende del contenido de arcilla, la geometría de poro, la porosidad, la saturación de fluido y, finalmente, la conductividad eléctrica del fluido poroso. Los primeros cuatro factores caracterizan las propiedades petrofísicas e hidrofísicas de la roca. Este último es el más importante, ya que es el principal factor que controla la conductividad eléctrica de la mayoría de las rocas sedimentarias no arcillosas.La resistividad de las rocas sedimentarias depende de varios factores y, por lo general, es poco probable obtener una interpretación inequívoca de las anomalías observadas en términos de estructura geológica sin información petrofísica e hidrofísica adicional. En muchos casos, cuando sean dispones los datos o, por lo menos, algunas estimaciones de las propiedades litológicas, petrofísicas e hidrofísicas de los sedimentos (contenido de arcilla, geometría del espacio poroso, saturación de fluidos, salinidad típica de las salmueras), es posible estimar la porosidad efectiva o contenido de arcilla. Debido a su capacidad de estimar las propiedades de yacimiento de la roca sedimentaria y/o las propiedades de la roca de cubierta con base en la conductividad eléctrica, el método MT podría ser especialmente útil en la prospección de hidrocarburos.
Las formaciones geológicas favorables para MT son las cuencas sedimentarias cubiertas con una gruesa capa de basalto o permafrost. Como ejemplos pueden servir las trampas siberianas en Rusia, la cuenca del Paraná en Brasil [Palshin et al., 2017], así como las cuencas sedimentarias cubiertas por basaltos de Deccan en India. Además, MT es uno de los métodos complementarios y eficientes de prospección de hidrocarburos en las cuencas sedimentarias intracratónicas del Mar del Norte y en las zonas de cabalgamiento, como Zagros en Irán, el cinturón plegado Subandino en Perú y Bolivia o la Depresión Yenisei-Khatanga en Siberia. Otro tipo de cuencas sedimentarias donde MT es muy eficaz está asociado con la tectónica de domo de sal [p.ej. Aleksanova et al., 2009]. Los diapiros de sal se encuentran en muchas cuencas sedimentarias que tienen unos depósitos de sal cubiertos por las formaciones con un espesor bastante grande, así como en las áreas de cinturones plegados. Los diapiros de sal clásicos (domes) se forman debido a la inestabilidad gravitacional en las regiones que no han sufrido un estrés tectónico significativo; sin embargo, algunos domos de sal se encuentran en las regiones tectónicamente activas. El primer tipo se encuentra en las áreas de tectónica de sal en el Golfo de México, el norte de Europa continental, el Mar del Norte y la depresión del Caspio, mientras que los diapiros de sal de Oriente Medio, que se encuentran en Irak, Irán y la Península Arábiga, pertenecen al segundo tipo.
La magnetotelúrica tiene ciertas ventajas en cuando se aplica para mapear la estructura en las zonas plegadas, donde los límites geológicos se caracterizan por los ángulos grandes de buzamiento, lo que también dificulta la interpretación de los datos sísmicos. Los cinturones plegados de Subandian, Taimyr, Zagros, Sinú de Colombia, son unos de los ejemplos de las áreas plegadas con el petróleo y gas prometedor [Palshin et al., 2021]. La conductividad eléctrica de las rocas sedimentarias depende del contenido de arcilla, la geometría de poro, la porosidad, la saturación de fluido y, finalmente, la conductividad eléctrica del fluido poroso. Los primeros cuatro factores caracterizan las propiedades petrofísicas e hidrofísicas de la roca. Este último es el más importante, ya que es el principal factor que controla la conductividad eléctrica de la mayoría de las rocas sedimentarias no arcillosas.La resistividad de las rocas sedimentarias depende de varios factores y, por lo general, es poco probable obtener una interpretación inequívoca de las anomalías observadas en términos de estructura geológica sin información petrofísica e hidrofísica adicional. En muchos casos, cuando sean dispones los datos o, por lo menos, algunas estimaciones de las propiedades litológicas, petrofísicas e hidrofísicas de los sedimentos (contenido de arcilla, geometría del espacio poroso, saturación de fluidos, salinidad típica de las salmueras), es posible estimar la porosidad efectiva o contenido de arcilla. Debido a su capacidad de estimar las propiedades de yacimiento de la roca sedimentaria y/o las propiedades de la roca de cubierta con base en la conductividad eléctrica, el método MT podría ser especialmente útil en la prospección de hidrocarburos.
Cinturón plegable de Taymyr, Rusia
Desde 2005 Nord-West participa en los estudios geofísicos múltiples en el territorio de la península de Taymyr (la parte norte de Siberia, Rusia). The total length of the completed survey lines is about 20 000 lin. km. The main components of the geophysical technology applied for the studies of both the Mountain Taymyr and the Yenisei-Khatanga Trough, are the 2-D CMP seismic survey and the MT. Also, the previously collected data of gravity and magnetic prospecting have been utilized for the interpretation. MT acquisition was conducted along the seismic lines and a joint interpretation of resistivity and seismic images with the involvement of gravity and magnetic prospecting data made it possible to clarify the understanding of the geological structure of the region to identify a series of large previously unknown geological objects that aren’t exposed at the earth’s surface and identify hydrocarbon-prospective areas as well.
Fig. 1 shows the geophysical studies results along one of the survey lines. In the middle part of the line, a large Gydan-Taymyr Trough has been mapped, with the thickness of the sedimentary formation reaching 20 km (filled with about 10 km of Paleozoic sediments and the Upper Riphean sequence of comparable thickness). A joint analysis of the seismic and resistivity models has shown that the largest anomalies of the seismic wave field coincide with the resistivity anomalies; taking the available paleo reconstructions into account, it can be assumed that these anomalies correspond to reef structures and manifestations of salt-dome tectonics (Fig. 2). It was concluded that the distinct-boundary high-resistivity zones correspond to the regions of loss of correlation between the seismic reflectors and resistivity boundaries. In one case, those anomalies are accompanied by low gravity field, which suggests that they might be associated with low-density anhydrite bodies (salt domes), while other certain resistive regions fall within the elevated gravity field zones, which is the evidence for their carbonate (reef) origin.
Desde 2005 Nord-West participa en los estudios geofísicos múltiples en el territorio de la península de Taymyr (la parte norte de Siberia, Rusia). The total length of the completed survey lines is about 20 000 lin. km. The main components of the geophysical technology applied for the studies of both the Mountain Taymyr and the Yenisei-Khatanga Trough, are the 2-D CMP seismic survey and the MT. Also, the previously collected data of gravity and magnetic prospecting have been utilized for the interpretation. MT acquisition was conducted along the seismic lines and a joint interpretation of resistivity and seismic images with the involvement of gravity and magnetic prospecting data made it possible to clarify the understanding of the geological structure of the region to identify a series of large previously unknown geological objects that aren’t exposed at the earth’s surface and identify hydrocarbon-prospective areas as well.
Fig. 1 shows the geophysical studies results along one of the survey lines. In the middle part of the line, a large Gydan-Taymyr Trough has been mapped, with the thickness of the sedimentary formation reaching 20 km (filled with about 10 km of Paleozoic sediments and the Upper Riphean sequence of comparable thickness). A joint analysis of the seismic and resistivity models has shown that the largest anomalies of the seismic wave field coincide with the resistivity anomalies; taking the available paleo reconstructions into account, it can be assumed that these anomalies correspond to reef structures and manifestations of salt-dome tectonics (Fig. 2). It was concluded that the distinct-boundary high-resistivity zones correspond to the regions of loss of correlation between the seismic reflectors and resistivity boundaries. In one case, those anomalies are accompanied by low gravity field, which suggests that they might be associated with low-density anhydrite bodies (salt domes), while other certain resistive regions fall within the elevated gravity field zones, which is the evidence for their carbonate (reef) origin.
Fig. 1. Overlayed seismic and resistivity images (top) and final model interpreted in terms of geological structure (bottom). The black lines indicate the major faults.
Fig. 2. An example of the identification of salt domes based on the joint analysis of resistivity and seismic images. The top surface of the salt domes is shown with a black line.
Cinturón Plegado Subandino, Bolivia
El proyecto único de MT y TDEM (hasta el momento de su finalización, el más grande de América Latina) fue llevado a cabo en 2017 por Nord-West en cooperación con Bolpegas SRL en virtud de un contrato con la empresa nacional boliviana de petróleo y gas YPFB. El objetivo principal fue comprender mejor la estructura geológica de la cuenca sedimentaria y el sistema petrolero en las dos áreas de estudio: Subandino Sur y Subandino Norte.
Para adquirir 3628 sondeos de MT y 1130 de TDEM en menos de 1 año, Nord-West trajo a Bolivia más de 50 operadores de campo con una alta experiencia y utilizó la gran cantidad de reseptores MT a la vez (54 conjuntos de MT en campo a la vez). En la logística de campo se incluyó el transporte todoterreno, los ferrys y barcos, los helicópteros, así como las marchas a pie de larga distancia y establecimiento de los campamentos remotos en la jungla.La tecnología empleada se concistía de la adquisición de datos MT de banda ancha en el rango de período de 0.0001 a 1000 s. The data were acquired about 14 –20 h (overnight) for better quality. Los datos estaban grabando mas que 14 h durante la noche para obtener una mejor calidad. Más detalles se encuentra en [Palshin et al., 2020].
El proyecto único de MT y TDEM (hasta el momento de su finalización, el más grande de América Latina) fue llevado a cabo en 2017 por Nord-West en cooperación con Bolpegas SRL en virtud de un contrato con la empresa nacional boliviana de petróleo y gas YPFB. El objetivo principal fue comprender mejor la estructura geológica de la cuenca sedimentaria y el sistema petrolero en las dos áreas de estudio: Subandino Sur y Subandino Norte.
Para adquirir 3628 sondeos de MT y 1130 de TDEM en menos de 1 año, Nord-West trajo a Bolivia más de 50 operadores de campo con una alta experiencia y utilizó la gran cantidad de reseptores MT a la vez (54 conjuntos de MT en campo a la vez). En la logística de campo se incluyó el transporte todoterreno, los ferrys y barcos, los helicópteros, así como las marchas a pie de larga distancia y establecimiento de los campamentos remotos en la jungla.La tecnología empleada se concistía de la adquisición de datos MT de banda ancha en el rango de período de 0.0001 a 1000 s. The data were acquired about 14 –20 h (overnight) for better quality. Los datos estaban grabando mas que 14 h durante la noche para obtener una mejor calidad. Más detalles se encuentra en [Palshin et al., 2020].
The Subandean fold belt is a thin-skinned in-sequence system with several detachment levels. The geological structure of the Subandean fold belt is typical for many fold belts characterized by a quasi-2D structure with wide relatively low resistivity synclines with horizontal layering and narrow complicated anticlines often fragmented by a large number of fault zones and subvertical layering forming mountain ridges with steep slopes. Disharmonic folding is also typical for this region: folding in upper structural levels does not coincide with those in the lower levels.
The Subandean fold belt is characterized by very complex structures with steep (even vertical) dips in the anticline nuclei. Available seismic data have not provided enough information in the axis of the structures, which might lead to a false interpretation when planning exploration wells. Detailed MT studies were carried out in addition to seismic acquisition to understand the structural behavior of the study area.
The Subandean fold belt is characterized by very complex structures with steep (even vertical) dips in the anticline nuclei. Available seismic data have not provided enough information in the axis of the structures, which might lead to a false interpretation when planning exploration wells. Detailed MT studies were carried out in addition to seismic acquisition to understand the structural behavior of the study area.
Fig. 3. MT projects in Subandean Fold Belt, Bolivia:
1 – Subandino Norte, 2 – Subandino Sur, 3 – Itacaray.
1 – Subandino Norte, 2 – Subandino Sur, 3 – Itacaray.
Subandino Norte
Broadband MT data were acquired along 15 profiles following old seismic profiles with length from 30 to 50 km oriented across geological strike. Due to quasi-2D structure of the Subandean fold belt the main interpretation tool was a 2D inversion. A TM mode in our particular case is more informative, but a bimodal inversion with a downweighted TE mode at a limited period band clearly gave the best result. Theoretically TM mode has a better resolution to resistive targets, while TE is responsible for imaging conductive objects, but in practice for real geological settings even for quasi-2D fold belts where targets are geological structures, which could be both resistive (anticlines) and conductive (synclines) a bimodal inversion is preferable. There is also another reason for applying a bimodal inversion: a regularized 2D inversion of TM mode-only data in some cases can result in “overfitting”, when a number of artefacts appear in resistivity images. These artefacts are caused by deviation of a real structure from a 2D one. Application of a bimodal inversion even with a downweighted TE mode helps to avoid such situations and obtain reliable resistivity images for both resistive anticlines and conductive synclines. A case study showed that a 2D bimodal inversion with a reference background resistivity model as a starting one (soft constraint) is the most efficient approach. The procedure consists of three main stages: (1) unconstrained 2D and 3D MT data inversion, (2) construction of 2D reference background resistivity models using all available data: unconstrained MT data inversion, seismic and logging data and constrained inversion – in our case MT data inversion with a reference background model as starting one. An example of resistivity image is shown in Fig. 4.
Broadband MT data were acquired along 15 profiles following old seismic profiles with length from 30 to 50 km oriented across geological strike. Due to quasi-2D structure of the Subandean fold belt the main interpretation tool was a 2D inversion. A TM mode in our particular case is more informative, but a bimodal inversion with a downweighted TE mode at a limited period band clearly gave the best result. Theoretically TM mode has a better resolution to resistive targets, while TE is responsible for imaging conductive objects, but in practice for real geological settings even for quasi-2D fold belts where targets are geological structures, which could be both resistive (anticlines) and conductive (synclines) a bimodal inversion is preferable. There is also another reason for applying a bimodal inversion: a regularized 2D inversion of TM mode-only data in some cases can result in “overfitting”, when a number of artefacts appear in resistivity images. These artefacts are caused by deviation of a real structure from a 2D one. Application of a bimodal inversion even with a downweighted TE mode helps to avoid such situations and obtain reliable resistivity images for both resistive anticlines and conductive synclines. A case study showed that a 2D bimodal inversion with a reference background resistivity model as a starting one (soft constraint) is the most efficient approach. The procedure consists of three main stages: (1) unconstrained 2D and 3D MT data inversion, (2) construction of 2D reference background resistivity models using all available data: unconstrained MT data inversion, seismic and logging data and constrained inversion – in our case MT data inversion with a reference background model as starting one. An example of resistivity image is shown in Fig. 4.
Fig. 4. Resistivity model obtained by 2D bimodal inversion for exemplary profile at Subandino Norte with seismic data overlapped. Survey site locations are shown by triangles. Main structures: A1 – Lliquimuni anticline, A2 – Tacuaral anticline,
S1 – Mayaya syncline, S2 – Inicua syncline, R1 – resistive Paleozic sediments, R2 – crystalline basement [Palshin et al., 2020].
S1 – Mayaya syncline, S2 – Inicua syncline, R1 – resistive Paleozic sediments, R2 – crystalline basement [Palshin et al., 2020].
The results of MT data interpretation are presented as a scheme of the depth to Devonian sediments (second structural level) and a scheme of geological structure of upper structural level with faults zones outlined (see Fig. 5 and 6). Two structural resistivity levels were identified in resistivity images. Resistivity structural levels differ in resistivity and rheological properties: the lower one in more resistive and brittle, while the upper one is much less resistive and ductile. This fact determines disharmonic folding in the survey area. The boundary between levels corresponds approximately to the top of Gr. Retama (or Tomachi) Devonian formation, which shows how an important geological boundary (detachment) could be imaged by MT.
Depth to the top of Devonian formations differs in the northeastern and southwestern parts of the survey area: boundary between two regions could be defined (see Fig. 5 and 6). The structures (anticlines) in the upper level do not coincide with uplifts in the lower level. It's worth mentioning that Gr. Retama and lower Devonian formations are the main source rocks in the northern part of Subandean fold belt. At the NW part of the survey area the depressions with depth up to 8 km (a.s.l.) divided by elongated uplift 4–5 km was imaged, while at the south-eastern part a depression with depth about 5 km dividing two uplifts with depth up to 2 km was outlined. The topography of top of the of Gr. Retama formations correlates with structures outlined by surface geology only in a limited area (SE end of Lliquimuni anticline), while the rest part of the survey area spatial correlation of structures of in the upper and lower level is absent. Thus, the elongated depression is located in the NW part of the area and coincides with NW extension of Liquimuni anticline.
Depth to the top of Devonian formations differs in the northeastern and southwestern parts of the survey area: boundary between two regions could be defined (see Fig. 5 and 6). The structures (anticlines) in the upper level do not coincide with uplifts in the lower level. It's worth mentioning that Gr. Retama and lower Devonian formations are the main source rocks in the northern part of Subandean fold belt. At the NW part of the survey area the depressions with depth up to 8 km (a.s.l.) divided by elongated uplift 4–5 km was imaged, while at the south-eastern part a depression with depth about 5 km dividing two uplifts with depth up to 2 km was outlined. The topography of top of the of Gr. Retama formations correlates with structures outlined by surface geology only in a limited area (SE end of Lliquimuni anticline), while the rest part of the survey area spatial correlation of structures of in the upper and lower level is absent. Thus, the elongated depression is located in the NW part of the area and coincides with NW extension of Liquimuni anticline.
Fig. 5. Depth to the top of the second structural level. The boundary between two regions is shown by red dotted line. Black dashed lines show the location of Lliquimuni and Tacuaral anticlines axis. The location of observation sites is show as dots [Palshin et al., 2020].
Fig. 6. Geological structure of upper level. Resistivity at levels 0 m (a) and 1200 m (b).
1- backthrusts, 2- overthrusts, 3 – strike-slip [Palshin et al., 2020].
1- backthrusts, 2- overthrusts, 3 – strike-slip [Palshin et al., 2020].
Another example is clearly seen in the SE part of the survey area where wide uplift the surface of Paleozoic formations coincides with two surface structures: Southern Inicua syncline and Sillar Anticline (see Fig. 5 and 6). The disconformity of structural levels could be explained by geological history and indicates only partial involvement of the lower structural level in the main phase of Andean folding. The lower structural level is characterized by resistivity increasing with depth and by duplex folding according to seismic data. Large numbers of fault zones were outlined in the upper structural level (see Fig. 6) by using resistivity models. Lliquimuni and Tacuaral anticlines are characterized by complicated structure (palm-tree structures). It could be explained by the peculiarity of stratigraphic sequences in the study area: interlayering of ductile clayish sediments and ductile sandstones and limestones. Clay searing is expected to be an important process responsible for fluid migration and accumulation in Subandean fold belt. Despite the spatial resolution of the resistivity images is less than that of seismic stacks, they give valuable additional independent information. In particular, for the northern Subandean fold belt geological settings MT gives the true position of the buried axes of anticlinal folds in lower structural level corresponding to Carboniferous-Devonian formations. The use of MT data opens the possibility of correcting seismic results using modern approaches to joint inversions and vice versa – updating resistivity images using constraints from seismic data interpretation. Integrated approach, which includes joint application of seismic and MT method could open fresh opportunities of effective exploration of fold and thrust belts, which are commonly considered as ‘difficult’ places to explore for hydrocarbons [Palshin et al., 2020, 2021].
Conclusions
The MT method is increasingly used in hydrocarbon prospecting. It provides important information about the structure of buried folds, complex salt bodies and fault zones. The results of magnetotelluric studies make it possible to solve both structural and petrophysical problems in the search and exploration of hydrocarbons and deep aquifers.
The experience of studying areas of complex geological structure shows the feasibility of combining various geophysical methods to reduce the uncertainties of geological models. The use of MT data in combination with seismic survey and logging data besides other geological and geophysical studies can significantly increase the reliability of mapping prospective structures and determining the targets of exploratory drilling.
The MT method is increasingly used in hydrocarbon prospecting. It provides important information about the structure of buried folds, complex salt bodies and fault zones. The results of magnetotelluric studies make it possible to solve both structural and petrophysical problems in the search and exploration of hydrocarbons and deep aquifers.
The experience of studying areas of complex geological structure shows the feasibility of combining various geophysical methods to reduce the uncertainties of geological models. The use of MT data in combination with seismic survey and logging data besides other geological and geophysical studies can significantly increase the reliability of mapping prospective structures and determining the targets of exploratory drilling.
Referencias
Aleksanova E.D., Alekseev D.A., Suleimanov A.K., and Yakovlev A.G., 2009. Magnetotelluric studies in salt-dome tectonic settings in the Pre-Caspian depression, First Break, vol. 7, no. 3, pp. 105-109.
Berdichevsky M.N. Electrical prospecting using telluric current method (en Ruso), Moscow: Gostopteckhizdat, 1960.
Berdichevsky M.N. Electrical prospecting using magnetotelluric profiling method (en Ruso), Moscow: Nedra, 1968.
Keller G. Electrical prospecting for oil, Quarterly Journal of the Colorado School of Mines, 1968, vol. 63, no 2, pp. 1-268.
Palshin, N.A., Aleksanova, E.D., Yakovlev, A.G., Yakovlev, D.V. and Breves Vianna, R., 2017. Experience and prospects of magnetotelluric soundings application in sedimentary basins, Geophysical Research, 2017, V.18, No 2. P. 27-54
Palshin, N.A., Giraudo, R.E., Yakovlev, D.V. Zaytsev, S. V, Aleksanova, E.D., Zaltsman, R.V. and Korbutiak, S. V., 2020. Detailed magnetotelluric study of the northern part of Subandian fold belt, Bolivia, Journal of Applied Geophysics, 2020, V.181, 104-136
Palshin, N.A., Sobornov, K.O., Bolourchi, M.J., Aleksanova, E.D., Yakovlev, D.V., Aliyari, A., Yakovlev, E.D., 2021. Magnetotelluric studies of fold belts (en Ruso). Geofizika, 2021(4): 81-95.
Vozoff K. The magnetotelluric method in the exploration of sedimentary basins, Geophysics, 1972, vol. 37, pp. 98-141.
Aleksanova E.D., Alekseev D.A., Suleimanov A.K., and Yakovlev A.G., 2009. Magnetotelluric studies in salt-dome tectonic settings in the Pre-Caspian depression, First Break, vol. 7, no. 3, pp. 105-109.
Berdichevsky M.N. Electrical prospecting using telluric current method (en Ruso), Moscow: Gostopteckhizdat, 1960.
Berdichevsky M.N. Electrical prospecting using magnetotelluric profiling method (en Ruso), Moscow: Nedra, 1968.
Keller G. Electrical prospecting for oil, Quarterly Journal of the Colorado School of Mines, 1968, vol. 63, no 2, pp. 1-268.
Palshin, N.A., Aleksanova, E.D., Yakovlev, A.G., Yakovlev, D.V. and Breves Vianna, R., 2017. Experience and prospects of magnetotelluric soundings application in sedimentary basins, Geophysical Research, 2017, V.18, No 2. P. 27-54
Palshin, N.A., Giraudo, R.E., Yakovlev, D.V. Zaytsev, S. V, Aleksanova, E.D., Zaltsman, R.V. and Korbutiak, S. V., 2020. Detailed magnetotelluric study of the northern part of Subandian fold belt, Bolivia, Journal of Applied Geophysics, 2020, V.181, 104-136
Palshin, N.A., Sobornov, K.O., Bolourchi, M.J., Aleksanova, E.D., Yakovlev, D.V., Aliyari, A., Yakovlev, E.D., 2021. Magnetotelluric studies of fold belts (en Ruso). Geofizika, 2021(4): 81-95.
Vozoff K. The magnetotelluric method in the exploration of sedimentary basins, Geophysics, 1972, vol. 37, pp. 98-141.