鄂尔多斯盆地延长组储层质量差异化和影响因素

Differences in Reservoir Quality and Influencing Factors of Yanchang Formation in the Ordos Basin

鄂尔多斯盆地延长组是致密油富集的主要层系,其砂岩储层具低孔低渗特征,油气垂向和平面分布主要受储层质量差异性影响。基于岩心、分析化验、测井和录井资料,分析储层质量差异性成因和影响因素。研究表明:①延长组储层物性属低孔-特低渗储层,垂向上油层组之间有差异,长2+3储层物性好于长6、长8储层。引起储层质量差异的原因主要是储层形成的沉积环境和成岩作用;②沉积相带差异和碎屑粒径是影响储层物性的原因之一,水下分流河道微相和砂质碎屑流沉积储层具较厚的砂体叠置和较高的储层物性,浊流次之,碎屑粒径越大,物性越好;③成岩作用是造成储层垂向物性差异的主要原因之一。长2+3储层埋藏浅,压实作用普遍较弱,胶结作用主要为高岭石自生矿物的胶结。长6、长8经历强烈压实作用,胶结作用主要为碳酸盐矿物胶结、绿泥石胶结和伊利石胶结,长6储层碳酸盐矿物胶结是储层物性变差的主要原因。含油气盆地中,油气充注、构造作用和事件性沉积等都是引起储层质量差异的因素。

Yanchang Formation is the main layer of tight oil enrichment in the Ordos Basin.Its sandstone reservoirs have low porosity and ultra low permeability.characteristics.The distribution of oil and gas in the vertical and on the plane is mainly affected by the reservoir quality variation.Based on core datum,analysis of laboratory datum,logging and logging datum,the reasons and influencing factors of reservoir quality are analyzed.The results showed that the physical properties of the Yanchang Formation are low-porosity-ultra-low permeability reservoirs,and there are differences between vertical oil-layer groups,and the physical properties of Chang 2+3 reservoirs are better than those of Chang 6 and Chang 8 reservoirs.The reasons for the difference in reservoir quality are mainly the sedimentary environment and diagenesis of reservoir formation.The difference of sedimentary facies and the size of debris particles are one of the reasons affecting the physical properties of reservoirs,and the microfacies of underwater distributary channels and sandy clastic flow sedimentary reservoirs have thicker sand body overlap and higher reservoir physical properties,followed by turbidity;The larger the particle size of the debris,the better the physical properties.Diagenesis is one of the main reasons for the difference in vertical physical properties of reservoirs.The Chang 2+3 reservoir is shallowly buried,and the compaction is generally weak,and the cementation effect is mainly manifested as the cementation of kaolinite autogenic minerals.Chang 6 and Chang 8 have undergone strong compaction,and the cementation effect is mainly manifested as carbonate mineral cementation,chlorite cementation and illite cementation,especially carbonate mineral cementation in Chang 6 reservoir is the main reason for the deterioration of the physical properties of the reservoir.In oil-bearing basins,oil and gas injection,tectonic action and event sedimentation are all factors that cause reservoir quality differences.