渤海湾盆地冀中坳陷天然气地质条件、资源潜力及勘探方向

Geological conditions,resource potential and exploration direction of natural gas in Jizhong Depression,Bohai Bay Basin

自中国第三次资源评价以来,渤海湾盆地冀中坳陷北部新钻井揭示了深层发育厚层烃源岩,并且牛东潜山、杨税务潜山等相继获得重要突破,预示着冀中北部具有较好的天然气勘探前景,有必要对天然气资源潜力重新评价。通过冀中北部天然气藏地质条件综合研究表明,充足的气源是天然气富集的物质基础,二级构造带是天然气的主要富集带,优质盖层是天然气富集的关键,总结建立了新生古储、自生自储及下生上储3种类型的成藏模式。按照"层、区带"的研究思路,综合盆地模拟、类比法及统计法等多方法开展常规天然气资源评价。结果表明:冀中坳陷总生气量达到19.5×10^(12) m^3,具备较强供气能力,天然气总地质资源量约为3 300×10~8 m^3,剩余天然气主要分布在冀中坳陷北部廊固凹陷、霸县凹陷及武清凹陷古近系深层及潜山领域,剩余地质资源约为3 000×10~8 m^3。依据成藏地质条件分析及剩余资源规模,综合评价优选出廊固凹陷中西部、河西务构造带、苏桥文安地区、码头—泗村店潜山带为冀中坳陷天然气增储上产的有利区带。

Since the 3th round of resource evaluation,new drillings show deep zones have thick hydrocarbon source rocks,and natural gas reserves were found in Niudong buried-hills and Yangsuiwu buried hills.h in dicated that northern Jizhong Depression has good gas exploration prospect. Natural gas resource potential need re-evaluate.Through study on gas reservoir geological conditions,it shows that sufficient gas source is the material basis for the natural gas enrichment,the secondary structural belt is the main enrichment re- gion with natural gas,high quality cover is the key to the natural gas enrichment.Three types of gas accu- mulation models are discovered and described as gas generated from young source rock and accumulated in old reservoir rock,self-generation and self-accumulation,and gas generated from lower source rock and ac cumulated in upper reservoir rock.According to the train of thought for studying the formations and zones, we evaluate natural gas resource through basin modeling,analog analysis and statistics.Jizhong Depression whose gas generation volume reaches 19.5×10^12m^ ,suggests strong supply capacity. Natural gas resource is estimatedas 3 300× 10^8m^3 ,which mainly distribute in the deep zones of Es and buried-hills in I.anggusag, Baxian Sag,Wuqing Sag located in northern Jizhong Depression. The remaining geological resource is still over 3 000×10^8m^3.After comprehensive assessment, central-western part of Langgu Sag,Hexiwu tectonic belt,Suqiao-Wenan area, Matou-Sicundian buried-hills are ranked most favorable play fairways enriched with remaining gas resources,as the favorable zones for increasing reserves of natural gas.