Applications of integrated geophysical exploration techniques for deep oil and gas targets in the Ordos Basin

The high-accuracy gravity survey was carried out to address the long-standing exploration constraints in the western margin of the Ordos Basin, such as the unclear structural pattern of the Lower Paleozoic, and the difficulty in highlighting the favorable areas and main hydrocarbon-generating strata. This paper proposes and applies the multi-interface gravity inversion of medium and shallow layers loosely constrained with few well, seismic and electromagnetic data, and a new technique to extract gravity anomalies caused by deep targets with the normalized gravity stripping based on the background density distribution of the basement. Gravity anomalies directly reflecting the thickness of the Lower Paleozoic were effectively obtained by improving the procedures and parameters of gravity stripping, which indicated that a Lower Paleozoic rift developed in the southern part of the western margin of the basin, where a very thick low-density stratum deposited and the potential area for oil and gas exploration is located. The successful applications guided the future oil and gas exploration for Paleozoic formations, and supported the oil and gas breakthrough of the YT3 well, which encountered oil and gas in the western margin of the basin, and provided an effective method and technique for oil and gas exploration in frontier areas, especially in the deep targets.