摘要
致密砂岩储层脆性评价对指导压裂施工等具有重要意义。针对目前岩石脆性评价中存在的脆性矿物不明确以及忽略成岩作用对岩石脆性影响的问题,首先根据鄂尔多斯盆地东北部某区块26块岩心样品的薄片、岩心资料和地层条件下的三轴压缩应力实验结果,系统地分析各矿物组分与岩石脆性的关系,明确石英和长石为研究区主要的脆性矿物;其次基于脆性指数与主要脆性矿物具有2种不同的相关关系,明确成岩作用、孔隙发育程度及类型差异对岩石脆性指数的影响;进而综合岩石中成岩矿物对孔隙发育程度及成岩作用的指示作用,利用石英和岩屑含量与长石含量的比值作为成岩作用的分类指标,将研究区致密砂岩储层分为Ⅰ类和Ⅱ类成岩作用储层;最终提出基于矿物组分和成岩作用的致密砂岩储层脆性评价方法,建立相应的脆性指数评价模型。利用该方法对鄂尔多斯盆地某致密气井的致密砂岩储层进行脆性评价,结果表明,基于矿物组分和成岩作用的脆性指数评价模型可以得到更为准确的致密砂岩储层脆性指数,为高脆性有利压裂目的层的识别及增产方案设计提供参数依据。
The evaluation of brittleness of tight sandstone gas reservoir is of great significance in guiding fracturing construction. In view of the problems that the brittle minerals could not be determined in the evaluation of the brittleness and ignorance of influence of diagenesis on the rock brittleness,first of all,the relationship between the mineral components and the brittle index was systematically analyzed according to information of thin sections,core data and the triaxial compressive stress under formation condition based on 26 samples from the block in the northeastern Ordos Basin. The quartz and feldspar are the main brittle minerals in the study area. Secondly,based on two different correlations of brittle index with the main brittle minerals,the influence of diagenesis,pore size and brittle mineral difference on the brittle index wasdetermined. And then the influence of the diagenetic minerals on the pore size and the degree of diagenesis was synthesized to classify tight sandstone reservoirs into two types ofⅠreservoir andⅡreservoir by using ratio of quartz and debris to feldspar content. Finally,the brittleness evaluation method for tight sandstone reservoirs based on mineral compositions and diagenesis was proposed and the corresponding brittle index evaluation model was established. The results show that the brittle index evaluation model based on mineral compositions and diagenesis can obtain more accurate brittle index of tight sandstone reservoir,which can provide parameter basis for the identification and stimulation of high-brittle fracturing target layer.
出处
《油气地质与采收率》
CAS
CSCD
北大核心
2017年第5期10-16,26,共8页
Petroleum Geology and Recovery Efficiency
基金
国家自然科学基金项目"致密气储层岩石导电机理研究及饱和度评价"(41404084)及"页岩油储层岩石物理特性数值模拟研究"(41504094)
油气资源与勘探技术教育部重点实验室(长江大学)开放基金项目"基于成岩相相控的致密砂岩储层饱和度建模及测井评价"(K2016-09)
关键词
致密砂岩储层
脆性评价
测井曲线
矿物组分
成岩作用
tight sandstone reservoir
brittleness evaluation
logging curves
mineral compositions
diagenesis
