西北大学学报(自然科学版)

在前人对鄂尔多斯盆地长7致密油储层特征研究的基础上,为了更好地确定合理致密油开发技术政策,按照全面和简洁的储层分类原则,筛选了有效孔隙度、有效吼道半径、可动油饱和度和启动压力梯度4项关键参数表征长7致密油的储渗特征;通过恒速压汞、启动压力梯度和可动油饱和度测试实验,建立有效孔隙度、有效吼道半径、可动油饱和度和启动压力梯度与储层渗透率的定量关系。依据将含油性评价和渗流能力评价相结合的原则,构建了致密油四元分类系数新方法。依据该方法,将四元分类系数值在1. 6～2. 3的分类为致密油Ⅰ类,在0～1. 6的分类为致密油Ⅱ类,在-3. 0～0的分类为致密油Ⅲ类。结合致密油不同类型水驱极限流动距离,初步形成了致密油Ⅰ类采用五点井网注水开发,致密油Ⅱ类初期采用自然能量开发,后期注水吞吐;致密油Ⅲ类初期采用自然能量开发,后期注气吞吐的3种开发方式。近年来,鄂尔多斯盆地长7致密油主要动用Ⅰ+Ⅱ类,均取得了较好的实施效果。

On the basis of previous studies on Chang 7 tight oil reservoir characteristics in Ordos Basin,in order to better determine the reasonable development policy of tight oil,the four key parameters of effective porosity,effective pore throat radius,the movable oil saturation and the threshold pressure gradient are selected to characterize Chang 7 tight oil reservoir under the comprehensive and concise way of reservoir classification.The quantitative relationships of reservoir permeability with the four parameters have been established by the testing results of constant-rate mercury injection,the threshold pressure gradient and movable oil saturation experiments. Combined with the petroleum-bearing and seepage capacity evaluation,the quaternary coefficients method has been newly created. Based on the new method,the tight oil can be categorized as Type Ⅰ whenits value of quaternary coefficient is 1. 6 to 2. 3,as Type Ⅱ when the value is 0 to 1. 6,and as Type Ⅲ when the value is-3. 0 to 0. Three development modes have been initially formed which Type Ⅰis applied to water-flooding with five-spot well pattern,Type Ⅱ applied natural energy development at the initial stage then water-injection and production at the late stage,and Type Ⅲ applied natural energy development at the initial stage then gas-injection and production at the late stage. The Type Ⅰ and Type Ⅱ of Chang 7 tight oil have been employed primarily in Ordos Basin in recent years,and have taken good implementation effects.