川中蓬莱地区须二段气藏特征及有利含气区预测

Gas reservoir characteristics of the second member of Xujiahe Formation and prediction of favorable gas bearing zones in Penglai area,central Sichuan Basin

川中蓬莱地区须二段显示出了良好的天然气勘探潜力,但由于储层孔隙结构和测井响应特征较为复杂,直接影响了其勘探开发效果。为了寻找须二段天然气有利聚集区,综合利用钻井岩心和薄片等资料,对成藏要素,即生、储、盖、运、圈、保的自身条件及其匹配关系等进行了探讨与总结,并对有利含气区进行了预测。结果表明:研究区须二段气藏具有充足的油气来源,且位于油气运移的有利方向,上覆的须三段泥岩为其有效区域盖层;具有有利的生、储、盖组合及良好的保存条件;研究区总体位于有利的构造-沉积相带,沉积作用是储层发育的基础,成岩作用是决定储层质量的关键,裂缝是决定储层产能的重要条件。对须二段有利含气区的预测研究可为其下一步天然气勘探提供地质依据,同时也有助于类似气藏有利含气区预测的研究。

The second member of Xujiahe Formation in Penglai area of central Sichuan Basin is of great potential for gas exploration,but on the other hand,the reservoir is also characterized by low porosity and low permeability,complicated pore structure and well logging response characteristics,so the exploration and development effect is influenced by these existing problems.In order to improve the oil and gas exploration degree and to find more high-quality reservoirs and favorable gas bearing zones,this paper studied the generation,storage,capping,migration,trapping and preservation of the second member of Xujiahe Formation together with their matching relationship with each other,and predicted the favorable gas bearing zones by making full use of drilling,logging,cores and slices data based on the previous research results.The research results show that：① the source rocks are of great potential for hydrocarbon-generating,and Penglai area is located in the superior place for gas accumulation with effective trap;② the mudstone of the third member of Xujiahe Formation can be effective cap rocks;③ source-reservoir-cap rock assemblage is in a good form,the relatively stable hydrodynamics are in good conditions for gas accumulation.The reservoirs of the second member of Xujiahe Formation are generally in the favorable tectonic and sedimentary facies belt.Sedimentation is the foundation for reservoir forming,diagenesis is the key points for reservoir quality,while the fracture development determines the productivity of reservoirs.The prediction of the favorable gas bearing zones can provide certain references for next exploration deployment in the study area,and it is favorable for the petroleum exploration in some areas with similar reservoir characteristics.