超深层碎屑岩油气藏渗流物理基础研究

Ultra deep reservoir is one of the key areas of oil and gas exploration and development. Due to the characteristics of complex geological features, high risk and it is difficult to be developed, geology, reservoirs, engineering multidisciplinary collaborative research is necessary. The main objective of this project focuses on the scientific problems of physical properties, seepage characteristics and their variation under formation conditions, and the physical experiment and theoretical study of seepage will be carry out. Firstly, reservoir physical properties, fluid saturation and its variation will be studied under reservoir conditions, as well as stress changes significantly, then porosity model, permeability model and original oil/water/gas saturation model will be established under formation conditions. In addition, the impact of significant changes in pressure on the seepage characteristics of the reservoir and the mechanism will be analyzed. A mathematical model of seepage flow considering dynamic change will be established. The characteristics of the multi-phase fluid seepage in the reservoir under high temperature and high pressure conditions will be studied, and the change mechanism of the multi-phase fluid seepage characteristics caused by the stress changes significantly will be revealed. And a three-dimensional seepage relative permeability curve model will be established. Finally, fluid flow law in micro-nano pore throat under high overburden pressure will be studied. By revealing the mechanism of oil and gas reservoir utilization, the lower limit map of ultra deep layer will be established. This research will provide theoretical support for the efficient development of deep oil and gas reservoirs.

超深层是油气勘探开发接续和发展的重点领域之一。面对超深层油气藏地质特征复杂、开发难度大、风险大的难点，需要地质、油藏、工程多学科协同攻关，本项目以碎屑岩超深层油气藏为对象，围绕‘储层条件下的物性、渗流特征及变化规律’的科学问题，开展渗流物理实验及理论研究。研究超深层油气藏储层原始条件下、以及应力状态“巨变”条件下储层岩石物性、流体饱和度及其变化，建立地层条件下孔、渗以及原始油水/气水饱和度精算模型。研究储层条件下的油、气藏的渗流特征，研究开发过程中‘大幅度’压力变动对储层渗流特性的影响及机理，建立考虑动态变化的渗流数学模型。研究储层高温压条件下的多相渗流特性，揭示‘大幅度’有效覆压变动引起的多相渗流特性的变化机理，建立“三维”渗流相渗曲线。研究有效覆压变化下微纳米孔喉内流体运动规律，揭示油、气藏储层动用机理，建立超深层动用物性下限图版。为形成深层油气藏高效开发技术提供理论支持。

针对我国超深层气藏地质特征复杂、开发难度大、风险大的特点，根据岩心孔渗参数、表面特征、微观孔隙结构，对龙王面组和震旦系灯影组碳酸盐岩气藏储层的岩心类型进行了划分。搭建高温高压实验平台，形成了地层条件下的渗流实验技术，通过常规条件和地层条件下的可视化实验、渗流实验、气水相渗实验、应力敏感实验、衰竭实验等多种实验和模型推导，得到了深层碳酸盐岩气藏在地层条件下的单相和气水两相渗流特征及其影响因素，确定了不同生产压差、储层厚度下的储层物性下限，评价了不同类型储层的应力敏感程度和采收率特征，并得到了层内和层间非均质以及生产制度、含水饱和度等对供气能力和产气速度的影响规律。研究结果表明，近井地带渗透率是影响深层碳酸盐岩气藏开发的关键。当近井地带渗透率相对较高时能够降低水平非均质性的影响，有效提高远井地带的动用程度；而如果近井地带渗透率过低则会抑制远井地带的动用程度，降低整体的采收率。水相的存在会降低衰竭速度和远井地带的供气能力。通过研究，为形成超深层气藏高效开发技术提供理论支持。