前陆盆地前隆带沉积演化及勘探方向OA

The forebulge zone is an important component of the foreland basin system.Due to its close proximity to hydrocarbon genera-tion centers such as foredeep zone and backbulge zone,it is rich in oil and gas resources.However,there is currently limited research on the sedimentary facies types and evolution of the forebulge zone.Based on logging,core,seismic,and analytical testing data,the sedi-mentary facies types,sedimentary facies evolution,and provenance of the forebulge zone were analyzed in detail,and the direction of oil and gas exploration in the forebulge zone was pointed out.It is held that tectonic activity is the main factor in the sedimentary evolution of the forebulge zone.The sedimentary facies types of the forebulge zone are simple,including braided river delta facies and lacustrine facies,among which braided river delta facies is the main sedimentary facies type of the forebulge zone.The sedimentation process of the forebulge zone is influenced by two main provenances:in the rising period of the forebulge zone(Carboniferous--early Jurassic),the central uplift area provides provenance for both sides of it,and the cessation period of tectonic activity in the forebulge zone(after the middle Jurassic),and the thrust nappe zone is the provenance of the forebulge zone.Due to changes in provenance and sedimentary fa-cies,the distribution characteristics of sand bodies in the slope area of the forebulge zone are different.The lower sand body is character-ized by the pinch out towards the high part of the forebulge zone structure,while the upper sand body is characterized by the pinch out towards the thrust nappe zone(in the opposite direction).Therefore,the lower strata are mainly focused on searching for lithofacies oil and gas reservoirs,while the upper strata are mainly focused on structural oil and gas reservoirs.This study clarifies the main controlling factors of sedimentary evolution,types of sedimentary facies and distribution laws of sand bodies in the forebulge zone of foreland ba-sins,providing an important theoretical basis for oil and gas exploration in such areas.