基于“岩石物理相-流动单元”测井响应定量评价特低渗透油藏优质储层——以延长油田东部油区长6油层组为例

Quantitative evaluation of favorable reservoir in ultra-low permeable reservoir based on“petrophysical facies-flow unit”log response:a case study of Chang 6 oil reservoir set in Yanchang Oilfield

岩石物理相和流动单元均可从不同角度表征储层的非均质性,鄂尔多斯盆地东部地区特低渗透储层非均质性极强,单独利用岩石物理相或流动单元对该地区进行储层评价会存在一定偏差。通过定性识别和定量划分,建立了"岩石物理相-流动单元"定量综合评价指标体系,并提出利用这一体系来定量评价优质储层。研究结果表明:一类、二类"岩石物理相-流动单元"具有较好的储集性能和渗流结构,由其圈定的近期可开发或评价后可开发的优质储层共49个,从而确定了含油甜点区的分布规律和延展方向。这一研究成果能兼顾岩石物理相对于油气富集的控制作用和流动单元的流动特性,可有效减小单独利用岩石物理相或流动单元筛选优质储层所造成的误差,现场应用效果较好,为研究区增储上产提供了有利井位和区域。

Petrophysical facies and flow unit can both represent the heterogeneity of the reservoir from different angles. The ultra-low permeability reservoir is characterized by strong heterogeneity in the eastern Ordos Basin, so there will be some deviations in reservoir evaluation by using petrophysical facies or flow unit. Combined with qualitative identification and quantitative classification, a comprehensive assessment target system of ＂petrophysical facies-flow unit＂ was established to quantitatively evaluate the high quality reservoirs. Meanwhile, it utilized grey system theory to integrate multiple information and established relationship between limited core da- ta and logging data, achieving to use well log information to quantitatively evaluate and divide ＂petrophysical fa- cies-flow unit＂. The results show that the first-class and the second-class＂petrophysical facies-flow unit＂ possess relatively preponderant reservoir properties and seepage structure, by which 49 high quality reservoirs was opti- mized for developing, and the distribution and extension direction of oiliness zones were determined. This meth- od can effectively reduce the error caused by the use of petrophysical facies or flow unit only to optimize high quality reservoirs. At the same time, the field application effect is good, and it also can provide favorable well site and district for enhancing reserve and productivity in the study area.