The Bohai Bay Basin is a typical oil-prone basin, in which natural gas geological reserves have a small proportion. In this basin, the gas source rock is largely medium-deep lake mudstone with oil-prone type II₂-II₁ kerogens, and natural gas preservation conditions are poor due to active late tectonic movements. The formation conditions of large natural gas fields in the Bohai Bay Basin have been elusive. Based on the exploration results of Bohai Bay Basin and comparison with large gas fields in China and abroad, the formation conditions of conventional large-scale natural gas reservoirs in the Bohai Bay Basin were examined from accumulation dynamics, structure and sedimentation. The results show that the formation conditions of conventional large natural gas reservoirs in Bohai Bay Basin mainly include one core element and two key elements. The core factor is the strong sealing of Paleogene “quilt-like” overpressure mudstone. The two key factors include the rapid maturation and high-intensity gas generation of source rock in the late stage and large scale reservoir. On this basis, large-scale nature gas accumulation models in the Bohai Bay Basin have been worked out, including regional overpressure mudstone enriching model, local overpressure mudstone depleting model, sand-rich sedimentary subsag depleting model and late strongly-developed fault depleting model. It is found that Bozhong sag, northern Liaozhong sag and Banqiao sag have favorable conditions for the formation of large-scale natural gas reservoirs, and are worth exploring. The study results have important guidance for exploration of large scale natural gas reservoirs in the Bohai Bay Basin.

渤海湾盆地是典型的易生石油盆地，天然气地质储量所占比例很小。在该盆地，气源岩主要为中深湖泥岩，油类易发类型为II ₂ -II ₁由于活跃的后期构造运动，干酪根和天然气的保存条件很差。渤海湾盆地大型天然气田的形成条件难以捉摸。根据渤海湾盆地的勘探成果，并与国内外大型气田进行比较，从成藏动力学，构造和沉积等方面研究了渤海湾盆地常规大型天然气藏的形成条件。结果表明，渤海湾盆地常规大型天然气藏的形成条件主要包括一个核心要素和两个关键要素。核心因素是古近纪“被子状”超压泥岩的强密封性。这两个关键因素包括后期烃源岩快速成熟和高强度气生成以及大型储层。在此基础上，建立了渤海湾盆地大规模天然气成藏模式，包括区域超压泥岩富集模型，局部超压泥岩减贫模型，富砂沉积下陷凹陷模型和晚期强发育断层消除模型。发现渤中凹陷，辽中北部凹陷和板桥凹陷具有形成大型天然气藏的有利条件，值得探索。研究结果对渤海湾盆地大型天然气藏的勘探具有重要的指导意义。包括区域超压泥岩富集模型，局部超压泥岩消耗模型，富砂沉积下陷凹陷模型和晚期强发育断层破坏模型。发现渤中凹陷，辽中北部凹陷和板桥凹陷具有形成大型天然气藏的有利条件，值得探索。研究结果对渤海湾盆地大型天然气藏的勘探具有重要的指导意义。包括区域超压泥岩富集模型，局部超压泥岩消耗模型，富砂沉积下陷凹陷模型和晚期强发育断层破坏模型。发现渤中凹陷，辽中北部凹陷和板桥凹陷具有形成大型天然气藏的有利条件，值得探索。研究结果对渤海湾盆地大型天然气藏的勘探具有重要的指导意义。并且值得探索。研究结果对渤海湾盆地大型天然气藏的勘探具有重要的指导意义。并且值得探索。研究结果对渤海湾盆地大型天然气藏的勘探具有重要的指导意义。