北部湾盆地低勘探程度凹陷烃源岩发育规律评价与潜力比选OA

To address the challenges of limited drilling data and the difficulty of evaluating exploration potential in low-explo-ration sags of the Beibu Gulf Basin,this study systematically assesses and compares the potential of such sags through de-tailed analysis and quantitative/semi-quantitative characterization of structural and depositional features during the hydrocar-bon source rock formation period.A systematic evaluation methodology,termed the"tectonic three-rate and sedimentary three-unit"approach,was established using hydrocarbon-rich sags as analogs to assess the distribution patterns and explora-tion potential of source rocks in low-exploration sags within the Beibu Gulf Basin.The results indicate that during the deposi-tion of the source rocks of the second member of the Liushagang Formation,the Beibu Gulf Basin was primarilly controlled by NE-trending faults,resulting in extensional tectonic styles and the development of single-fault half graben or double-fault gra-ben sag structures.The rate of fault activity,horizontal extension rate,and basement subsidence rate jointly controlled the structural framework and sedimentary infill of the sags.Significant differences are observed among the sags in terms of parent rock type and uplift rate,sediment dispersal systems and the locations of"grit chambers"during sediment transport,the scale of semi-deep to deep lacustrine environments,paleowater depth,paleo-oxidation conditions,and source-to-sink ratios during source rock deposition.Based on the comprehensive evaluation,two highly prospective subsags,the eastern subsag of the Haizhong sag and the eastern subsag of the Maichen sag,are identified as favorable exploration targets.