Utilizing Direct Hydrocarbon Indicators on 3D-Seismic Data to Prove the Existence of Hydrocarbon Accumulation in the Subtle Stratigraphic Trap in the Mishrif Reservoir at the Dujaila Oil Field, SE of Iraq

Abstract

The current study aims to utilize the Direct Hydrocarbon Indicators technique to identify the presence of hydrocarbons in the Carbonaceous Mishrif Formation (Late Cretaceous) from the 3D seismic data (post-stack) integrated with available information of two wells (Du-1 and Du-2). The 3D-seismic survey was carried out in 2010, covering 602.62 km2, at the Dujaila oil field in Maysan, SE of Iraq. Distinct seismic features for hydrocarbon presence indicators were diagnosed and identified on both sections of seismic amplitude and instantaneous phase, such as dim spots, flat spots, and phase polarity reversals. They helped in direct detecting the presence of hydrocarbon accumulation in the stratigraphic trap, in the region around well Du-1 at the upper part of Mishrif Formation, which is located at a time (TWT) extending from -1730 ms in the top Mishrif to underneath at TWT -1775 ms that corresponded with depth 2825 m to 2887.5 m, respectively. Furthermore, based on the well-defined position of a flat spot, which represents oil-water contact; it helped to determine the length of the oil column was 56.8 m in the vicinity of productive well Du-1. It is close to the actual length of the oil column measured in the well was 49 m. As a result, the circular area with a radius of about 3 km around well Du-1 is more suitable for low-risk drilling in the future.