深层油气藏盖层封闭能力动态演化过程及完整性定量评价

Taking the deep reservoir caprock in Tarim basin as the key anatomy object, based on the distribution of caprocks in different grades and the testing of parameters to characterize its sealing ability we analysis the diagenetic evolution stages and the sealing mechanism of deep reservoir caprock and then focus on the sealing ability of caprocks in different diagenetic stages. Based on the evolution law of displacement pressure and overpressure during burial - uplifting process and in combination with the conditions where fractures form to evaluate quantitatively the dynamic evolution sealing ability of the deep reservoir caprock. Making the triaxial loading and unloading tests to simulate the burial and uplifting processes and then testing the rock mechanics characteristics, according to mechanical parameters, fracture patterns and microscopic deformation structures we establish the standard of brittle - ductile deformation of caprocks and then research the brittle - ductile deformation characteristics of shale and anhydrite-salt rock during burial and uplift processes to establish the quantitative characterization methods. Make analysis of the internal structure of fault zone in different deformation stages based on the research on faults in outcrop and the microstructures in cores to set up the method to evaluate quantitatively the vertical sealing ability of faults. Based on the change of deep caprock wettability, the quantitative evaluation of the vertical sealing ability of faults, connectivity of fractures and the sand body we set up the quantitative evaluation method of the deep reservoir caprock integrity. Evaluating the dynamic evolution process of sealing ability and its integrity of deep reservoir caprock in Tarim basin, combined with its hydrocarbon distribution, we can analyze the effect of caprocks and faults in different grades on the formation and distribution of reservoirs.

以塔里木盆地深层油气藏盖层为重点解剖对象，在不同级别盖层分布规律和表征封闭能力参数测试的基础上，剖析深层盖层成岩演化阶段和封闭机理，研究不同成岩阶段盖层封闭能力。基于埋藏-抬升过程排替压力变化规律和超压演化规律，结合抬升过程裂缝产生条件，建立盖层封闭能力动态变化定量评价方法。模拟埋藏和抬升过程三轴加载和卸载试验，测试岩石力学特征，依据力学参数、破裂方式和显微变形构造建立盖岩脆-韧性变形标准，研究泥页岩和膏盐岩埋藏过程和抬升过程脆-韧性变形特征并建立定量表征方法，基于露头区断裂和岩心微构造研究，分析不同变形阶段断裂带内部结构，建立断裂垂向封闭能力定量评价方法。依据深层盖层润湿性变化、断裂垂向封闭能力评价、裂缝连通性和裂缝-砂体连通性，建立盖层完整性定量评价方法。对塔里木盆地深层油气藏盖层封闭能力动态演化过程及完整性进行评价，结合油气分布规律，分析不同级别盖层和断裂对油气藏形成和分布控制作用。

无论是深层还是浅层油气勘探，盖层封闭能力动态演化过程及完整性研究一直是油气勘探风险性评价的重要支撑。由于深层埋深、流体压力和构造抬升等多重作用，导致盖层变形机制认识尚不清楚，缺少有效的盖层动态封闭能力和完整性评价体系。本项目以深层盖层埋藏史和油气藏精细解剖为基础，提出了五种区域性深层盖层封盖油气模式，明确了不同层次盖层对油气分布的控制作用。明确了深层盖层毛细管和水力封闭两种封闭机理，提出了表征盖层封闭能力的主要参数，构建了埋藏过程中深层泥岩盖层封闭能力演化过程描述方法。以岩石力学测试为基础，明确了影响不同类型盖层脆韧性的主要因素，系统总结了盖层脆韧性判识标准，建立了盖层脆韧性转化过程定量评价方法；结合岩石力学特征、油藏解剖和地球化学示踪特征研究，构建了适用于不同脆韧性盖层条件下的断层垂向封闭性定量评价体系。提出了三种破坏盖层连通性及深层油气保存的类型：水力破裂、裂缝和亚地震断层-砂体。明确了盖层水力破裂原理和评价参数，建立了盖层水力破裂定量评价方法；基于野外和室内实验，建立了裂缝连通性定量判别标准；结合油藏解剖和分形技术，建立了亚地震断层-砂体连通性定量预测体系。最终，基于盖层成岩演化阶段、封闭能力动态演化过程、裂缝产生条件及连通性、断裂垂向封闭能力及演化过程和盖层水力破裂演化规律，以断裂控藏理论体系为指导，构建了深层盖层完整性定量评价体系，建立了不同类型盖层（砂泥互层型和厚层型）-断层共控油气成藏模式，形成了适用于深层油气勘探的盖-断共控油气富集理论体系。