鄂尔多斯盆地神木气田山2段砂岩成岩相定量划分及其特征差异

Quantitative Classification and Characteristics Difference of Diagenetic Facies in Shan 2 Sandstone of Shenmu Gasfield,Ordos Basin

为探讨成岩相的定量划分方法,以鄂尔多斯盆地神木气田山2段砂岩为研究对象,综合利用测井资料和实验测试结果,依据成岩和测井参数,建立了成岩相定量划分标准,阐述了不同成岩相的特征差异。研究区山2段砂岩岩性为岩屑石英砂岩、岩屑砂岩和石英砂岩,发育岩屑溶孔、晶间孔、粒间溶孔、杂基溶孔和粒间孔。经历了压实压溶作用、胶结作用和溶解作用,压实率中等—强,胶结率中等,溶解率中等—强。根据成岩作用定量参数划分出5种成岩相类型,基于自然伽马、深侧向电阻率、声波时差和密度测井建立的识别标准可进行有效区分。发育于分流河道砂体中间的中等压实伊利石胶结—粒间孔+溶蚀孔相,孔隙发育程度最高、物性最好,孔喉分布范围最宽,大孔喉含量高,是研究区最有利的成岩相带,中等压实伊利石、高岭石胶结—溶蚀孔+晶间孔相次之。

In order to probe the quantitative classification method of diagenetic facies,logging data and test results have been used to establish classification standard and state characteristics of diagenetic facies according to diagenesis and logging parameters taking Shan 2sandstone of Shenmu Gasfield in Ordos Basin as an example.The lithology is lithic quartz sandstone,lithic sandstone and quartz sandstone.It develops lithic dissolved pore,inter-crystalline pore,inter-granular dissolved pore,mixed solution pores and inter-granular pore.Shan 2sandstone experienced compaction pressure-solution,cementation and dissolution with medium to strong compaction rate,medium cementation rate,moderate to strong dissolution rate,respectively.Five types of diagenetic facies can be classified according to the diagenesis quantitative parameters and diagenetic facies can be effectively distinguished based on natural gamma ray,deep lateral resistivity,acoustic and density logging.The moderate compaction,illite cementation,intergranular pore and dissolution pore facies distributing in the middle of distributary channel sand body is the most favorable diagenetic facies because of the highest pore development degree,the best properties,the widest distribution of pore throat and high content of large pore throat,followed by moderate compaction,illite and kaolinite cementation,dissolution pore and intergranular pore facies.