ABSTRACT

The Nanpu sag is an important secondary tectonic division of the Bohai Bay Basin and has an area of 1532 km2 (591 mi2), of which 1000 km2 (386 mi2) has been explored near Bohai. Recently, exploration has gradually shifted from continental to beach to shallow-marine settings, with significant exploration breakthroughs having occurred in the Nanpu 1, 2, and 3 tectonic belts, indicating good resource potential. However, a systematic resource assessment has yet to be performed, which strongly restricts the exploration progress. In this study, we improved upon the Pareto model and reevaluated the area’s resource potential using two new methods. In one method, the traps are divided into several types, including structural, stratigraphic, and buried hill traps, to predict their individual resource potential and total resources of this area; in the other method, the normalized fluid potential is used to divide the area into several accumulation systems to calculate the resource potential. The Nanpu sag resources are estimated at 1.45 × 109 t (10.6 × 109 bbl), which represents an increase of approximately 2.70 × 108 t (19.8 × 108 bbl) compared with previous evaluations because of the increase in exploration maturity and information validation. The main residual resource is distributed in beach to shallow-marine settings. The stratigraphic and buried hill traps present better resource potential using the trap-type method. Such information can guide the direction of exploration and selection of potential traps.

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