鄂尔多斯盆地东缘雷家碛地区盒8段致密储层“甜点”预测

鄂尔多斯盆地东缘雷家碛地区盒8段广泛发育辫状河砂体，为典型的致密砂岩气储层。为解决因地震资料品质约束造成的气层预测困难问题，开展了实验室岩心分析测试等方面的研究。结果表明：①雷家碛地区盒8段以岩屑砂岩和长石岩屑砂岩为主，储集空间类型包括残余粒间孔、粒间溶孔、粒内溶孔等，面孔率低，孔喉分选差，孔隙结构复杂，为典型致密砂岩储层；②压实作用、压溶作用和胶结作用均为破坏性成岩作用，而溶蚀作用和构造破裂作用均有效改善了岩石的储集性；③各成岩作用对岩石的改造可引起岩石物理参数变化，依据在三维地震数据体中提取的"甜点"属性与叠前反演得到的泊松比属性，在平面上划分出建设性成岩作用所形成的有利区，可有效预测天然气富集区。根据上述方法部署的LX-41井，其钻探结果与预测结论较为一致。研究成果对类似区域的"甜点"预测具有一定的借鉴意义。

Sweet spot prediction of tight reservoir of He 8 member in Leijiaqi area,eastern margin of Ordos Basin

Braided river sand bodies are widely developed in He 8 member in Leijiaqi area,eastern margin of Ordos Basin,which is a typical tight sandstone gas reservoir. In order to solve the difficulty of gas reservoir prediction caused by poor quality of seismic data,laboratory core analysis and testing were carried out. The results show that:(1)The reservoir sandstones of He 8 member in Leijiaqi area are mainly lithic sandstone and feldspathic lithic sandstone. The reservoir spaces include residual intergranular pores,intergranular dissolved pores and intragranular dissolved pores. The reservoir is a typical tight sandstone reservoir with low porosity,poor pore throat sorting and complex pore structure.(2)Compaction,pressure dissolution and cementation are the main destructive diagenesis,while dissolution and structural fracturing can effectively improve the reservoir properties.(3)According to the variation of petrophysics parameters caused by different diagenesis,combined with the attributes of sweet spot extracted from 3 D seismic data and Poisson's ratio obtained by simultaneous pre-stack inversion,favorable areas formed by constructive diagenesis can be divided in plane,and gas enrichment areas can be effectively predicted. The drilling results of well LX-41 deployed according to the above methods are consistent with the prediction results. The research results have a certain guiding significance for the prediction of sweet spot in similar zones.