非均质超稠油疏松砂岩储层可压性评价

Evaluation of Fracability of Heterogeneous Ultra-Heavy Oil Loose Sandstone Reservoirs

目前国内针对超稠油疏松砂岩储层可压性尚无统一的评价方法。在研究新疆风城非均质超稠油储层可压性的基础上,用洛伦兹系数法评价储层的非均质性,定义超稠油储层可压性概念。选取多维地质工程参数作为评价新疆风城非均质超稠油储层可压性的指标,使用灰色关联法指导建立参数权重选取时的判断矩阵,采用灰色关联-层次分析法建立该类储层的可压性评价模型。计算新疆风城油田两个区块8个层段储层改造前的可压性系数,结果显示储层可压性与非均质性具有负相关关系。当储层可压性系数大于0.7时,对应洛伦兹系数小于0.5,通过微压裂储层改造后能获得较大的张性扩容量。该可压性评价方法能够判断非均质超稠油储层的可压性优劣,对现场微压裂改造具有一定的指导意义,帮助油田现场提高油井最终采收率。

At present,there is no standard method for evaluating the fracability of ultra-heavy oil loose sandstone reservoirs in China.On the basis of the study exploring the fracability of heterogeneous ultra-heavy oil reservoirs in Fengcheng,Xinjiang,the Lorenz coefficient method was used to evaluate the heterogeneity of reservoirs and define the concept of fracability of ultra-heavy oil reservoirs. Multidimensional geological engineering parameters were selected as indicators to evaluate the fracability of heterogeneous ultra-heavy oil reservoirs in Fengcheng,Xinjiang,the gray correlation method was used to guide the establishment of the judgment matrix when selecting parameter weights,and the gray correlation-hierarchy analysis method was used to establish the fracability evaluation model of this type of reservoir. The fracability indexes of eight layers of two blocks of the Xinjiang Fengcheng Oilfield before reservoir stimulation were calculated,which showed that the reservoir fracability index is negatively correlated with heterogeneity. When the reservoir fracability index is greater than 0.7,the corresponding Lorenz coefficient is less than 0.5,and larger tensile dilatancy can be achieved through microfracturing reservoir stimulation. This fracability evaluation method can help assess the fracability of heterogeneous ultraheavy oil reservoirs,which provides guidance for on-site microfracturing stimulation,and helps oilfields to improve the final oil recovery of wells.