库车前陆盆地深层致密砂岩储层构造成岩强度的定量评价方法

A quantitative evaluation method of structural diagenetic strength of deep tight sandstone reservoirs in Kuqa foreland basin

含油气盆地中储层的形成和演化受构造作用和成岩作用共同控制,构造成岩作用的定量评价对深入认识储层的形成演化过程及储层质量具有重要意义。通过分析构造成岩作用的内涵以及储层形成演化的主要影响因素,提出了利用构造成岩强度来定量表征构造作用和成岩作用对储层形成演化及储层质量的影响。构造成岩强度是指储层在形成演化过程中所受构造作用和成岩作用的影响程度,可以用构造成岩指数进行定量表征。构造成岩强度不仅能够反映储层在埋藏过程中所经历的时间、深度、温度和压力等成岩演化控制因素对储层的影响,同时还能够反映不同构造时期的构造变形强度及其演化对储层的影响。对库车前陆盆地深层白垩系致密砂岩储层开展的构造成岩强度定量评价表明,储层的形成演化与构造成岩强度密切相关,随着构造成岩强度增加,储层基质的孔隙体积减少,天然裂缝的发育程度增加。从库车前陆盆地山前构造带到前缘隆起带,构造成岩强度依次由大变小,储层的基质孔隙度逐渐增高,而天然裂缝发育程度则逐渐降低。构造成岩强度的定量评价方法可为深层致密砂岩储层的定量评价及预测提供新途径。

The formation and evolution of reservoirs in petroliferous basins are jointly controlled by tectonism and diagenesis.Quantitative evaluation of structural diagenesis is of great significance for deeply understanding the formation and evolution of reservoirs and reservoir quality.By analyzing the connotation of structural diagenesis and the main influencing factors for the formation and evolution of reservoir,this paper proposes that structural diagenetic strength can be used to quantitatively characterize the influence of tectonism and diagenesis on the formation and evolution of reservoirs and reservoir quality.Structural diagenetic strength refers to the degree of influence on tectonism and diagenesis during the formation and evolution of reservoir,which can be quantitatively characterized by the structural diagenetic index.The structural diagenetic strength can reflect not only the influence of time,depth,temperature,pressure and other controlling factors for the diagenetic evolution occurred during burial process on the reservoir,but also the impact of tectonic deformation intensity and its evolution in different structural periods on the reservoir.Quantitative evaluation of the structural diagenetic strength of the deep Cretaceous tight sandstone reservoirs in Kuqa foreland basin shows that the formation and evolution of reservoir is closely related to the structural diagenetic strength.As the structural diagenetic strength increases,the pore volume of reservoir matrix decreases and the development degree of natural fractures increases.From the piedmont structural belt to the frontal uplift belt of Kuqa foreland basin,the structural diagenetic strength successively increases from large to small;the matrix porosity of reservoir gradually increases,while the development degree of natural fractures gradually decreases.The quantitative evaluation method of structural diagenetic strength can provide a new way for the quantitative evaluation and prediction of deep tight sandstone reservoirs.