镇原地区长8储层特征及控制因素分析

Analysis of characteristics and influence factors of the Chang8 reservoirs in Zhenyuan area

针对镇原长8砂体变化快、储层影响因素复杂等现状，采用精细小层对比技术、储层综合评价法。并结合岩心分析资料，对长8储层特征及控制因素进行研究。结果表明，长8储层三角洲前缘沉积水下分流河道发育，岩性以岩屑长石砂岩为主，主要发育残余粒间孔和长石溶孔，渗流通道以微喉和细喉为主，为典型的低孔、特低孔和低渗、超低渗储层。储层物性受沉积作用控制，水下分流河道主砂体储层物性最好；压实和胶结作用使储层物性变差，而溶蚀作用产生的次生孔隙使储层物性得以改善。

In light of the status of quick change （ strong heterogeneity） of the sand bodies and complex influence factors of the Chang8 oil reservoirs in the Yanchang Formation in Zhenyuan area, a technique of careful correlation of single layers and comprehensive reservoir evaluation methods were utilized to study the characteristics and the controlling factors of the Chang8 oil reservoirs, combined with core analysis data. The study results show that underwater distributary channels developed in the delta front deposition of Chang8 reservoirs, with major lithology of lithic arkose; the major pores are residual intergranular pores and dissolved pores in feldspar; the chief percolation （seepage） channels are micro- and fine throats, being typical reservoirs with low-extra low porosity and low-ultra low permeability; the reservoirs physical properties are controlled by the sedimentation, and the reservoirs physical properties of the main sand bodies in the underwater distributary channels are the best; compaction and cementation can make the physical properties of the reservoir worse, but the secondary pores formed by dissolution improve the physical properties of the reservoirs.