Application of MT data in the study of ultra-deep basement structure of Precambrian in Tarim Basin

The magnetotelluric sounding (MT) method is characterized by large detection depth and strong ability to identify lithology, not shielded by the near-surface high resistivity layer. MT has been widely used as an essential approach to detect the deep earth structure. According to the requirements of the oilfield company, this work focuses on the study of the Precambrian ultra-deep geological structure guided by the plate tectonics theory. Based on the characteristics of geoelectric structure of several MT inversion sections in the basin, combined with the joint inversion technique of gravity, magnetic, electromagnetic and seismic on the plane, and guided by the theory of plate tectonics, the study on the ultra-deep geological structure of Precambrian system is carried out, and some new understandings are preliminarily obtained. From a non-seismic perspective, this paper provides new insights on the distribution of tectonic layers, such as the Neoproterozoic Nanhua-Sinian rift trough, the Mesoproterozoic Great Wall-Jixian system, the Taikoo-Middle-Lower Proterozoic. The new findings also include the discovery of the Mesoproterozoic residual oceanic crust in the northern basin, and the identification characteristics of the ancient subduction zones and the distribution characteristics of igneous rocks from both its north and south sides. It is found that the geological structure in the deep layer has a decisive effect on the oil and gas accumulation conditions of the entire basin, which provides significant guidance for the future exploration and deployment of oil and gas.