致密砂岩油藏成岩-烃类充注时序对微纳米孔隙结构的约束机制及石油充注孔喉下限研究

The nano-micro pore structure and oil-charging throat threshold in tight reservoirs are key factors of oil and gas accumulation, as well as evaluation and development of hydrocarbon in tight sandstone oil reservoirs, which would also controlled by digenetic-hydrocarbon filling sequence, but the coupling relationships among them are not clear yet, and the tight sandstone oil reservoir from the 8th Member of Yanchang Formation in Longdong Area as research objects. Tests and analysis in this research are based on the background of dynamics of basin reservoir formation and sandbody configuration unit to explain the modification and optimization that diagenesis has had on minerals and their pore appearance. Accordingly, diagenesis facies will be classified, in which hydrocarbon types, occurrence state, evolution characteristics key accumulation period and diagenetic-hydrocarbon filling sequence will be determined. The dissolution and sedimentation caused by acid-alkali diagenetic environment transformation in different pore scales will be explained and modeled. This research uses hydrodynamic equilibrium and Young-Laplace formula to model lower limits of threshold on the basis of maximum driving forces, thus provide theoretical foundation for reservoir evaluation and development.

致密油藏微纳米孔隙结构与石油充注孔喉下限是影响油气运聚成藏、评价和开发的关键因素。成岩-烃类充注时序对微纳米孔隙结构演化和石油充注孔喉下限具有控制作用，但它们之间的耦合关系和约束机制尚未厘清。课题以鄂尔多斯盆地陇东地区长8致密砂岩油藏为例，开展致密砂岩油藏成岩-烃类充注时序对微纳米孔隙结构的约束机制与石油充注孔喉下限研究。在盆地成藏动力学和成岩演化背景下，结合常规和先进的测试技术，基于砂体构型单元，阐明成岩作用对矿物和孔隙面貌的改造和优化作用，划分成岩相；厘定典型成岩相内烃类类型、赋存状态、演化特征、油气成藏关键期次及建立成岩-烃类充注时序；阐明不同孔喉尺度内烃类充注造成酸-碱性成岩环境转换过程中的溶蚀-沉淀作用及对孔隙结构的控制机制并建立预测模型；应用流体动力学平衡关系及Young-Laplace方程，基于最大充注动力建立石油充注孔喉下限理论模型。对致密油储层评价与开发提供理论依据。

致密油藏微纳米孔隙结构与石油充注孔喉下限是影响油气运聚成藏、评价和开发的关键因素，成岩-烃类充注时序是影响微纳米孔隙结构演化和石油充注孔喉下限的关键因素之一。当前针对成岩-烃类充注时序、微纳米孔隙结构、石油充注孔喉下之间的耦合关系和约束机制的研究较少。本研究以典型致密砂岩油藏为例，在明确盆地成藏动力学和成岩演化背景下，结合实验测试分析与数理统计模拟技术，划分了砂体构型单元，分析成岩演化特征，构建了岩石组构-孔喉结构模型，阐明成岩作用对矿物和孔隙面貌的改造和优化作用，划分成岩相，并建立了全尺度孔喉分布模式；明确了典型成岩相内烃类类型、赋存状态、演化特征、油气成藏关键期次及建立了成岩-烃类充注时序；阐明了不同孔喉尺度内烃类充注造成酸-碱性成岩环境转换过程中的溶蚀-沉淀作用、孔隙结构的演化特征、石油充注孔喉尺度，并建立了石油充注孔喉下限理论模型，并开展了分析评价。项目研究成果对探索致密砂岩油藏致密演化和油气充注机理提供了方法学基础，同时对致密砂岩油藏评价、预测和优选高品质“甜点”与开发具有实践意义和理论指导。在课题研究过程中，共发表SCI收录论文18篇与15篇中文核心论文，申请专利3项、其中授权专利2项，申请授权软件著作权1项，出版专著1部，获厅局级奖2项、其中1等奖1项、3等奖1项，培养1名硕士研究生与2名博士研究生，获得省级人才称号1名。