裂缝性致密砂岩储层裂缝孔隙度建模——以四川盆地平落坝构造须家河组二段储层为例

Fracture porosity modeling of fractured tight sandstone reservoir:a case study of the reservoir in Member 2 of Xujiahe Formation,Pingluoba structure,Sichuan Basin

裂缝性致密砂岩储层的非均质性突出,相对于沉积相变对储层所造成的影响,后期成岩与构造运动对储层的改造更重要,裂缝的发育特征常是影响这类储层有效性的关键因素。常规描述储层性质的孔隙度、渗透率参数难以确切描述该类储层的性质。在评价裂缝性致密砂岩储层时,将裂缝破碎带作为优质储层研究对象,以裂缝孔隙度作为储层评价关键参数,是研究裂缝性致密砂岩有效储层分布规律的重要途径。在裂缝孔隙度建模过程中,构造裂缝孔隙度的空间结构信息是建模的关键,在建立地震属性与裂缝的相关性基础之上,使用地震属性构造了裂缝孔隙度的空间结构参数。生产数据表明,地震分频属性能够在整体上指示裂缝孔隙度的平面分布特征,可以用来构造裂缝孔隙度的变差函数,但该属性不能定量给出裂缝孔隙度的空间分布特征,因此不能用于辅助参数进行协同计算。将地震蚂蚁体数据和通过成像测井校正的单井裂缝孔隙度解释数据共同作为模拟裂缝孔隙度模型的输入参数,使用协同建模的方法建立裂缝孔隙度的空间分布,从而定量评价了裂缝性致密砂岩储层裂缝孔隙度的空间展布规律,为数值模拟提供数据支持。

Fractured tight sandstone reservoirs are highly heterogeneous.In contrast to the effect of sedimentary facies change,diagenesis and tectonic movements play more important role.The properties and distribution of fractures are always the key factors to evaluate such type of reservoir.The porosity and permeability parameters,which are normally used to describe reservoir properties,could not describe fractured tight sandstone reservoir sufficiently.It is an important method to evaluate the distribution of the effective reservoir of the fractured tight sandstone by treating fracture porosity as a random variable and using it as a key evaluating parameter.Constructing the spatial structure of the fracture porosity is the key step for modeling,and therefore the spatial structure parameters created by using seismic properties after the correlation was established.Production data indicated that frequency spectral decomposition properties of seismic could show the similar plane distribution of the fracture porosity,and could be used to calculate the varigram of the fracture porosity.However,the properties were 2D and could not be used as secondary data in modeling.Ant tracking data of seismic and log interpreted fracture porosity being as input data and using collaborative modeling method to create the spatial distribution of the fracture porosity were established and then evaluated the reservoir quantitatively.