基于孔径分布和T_2谱的低孔渗储层渗透率确定方法

Permeability confirmation method of low porosity and permeability reservoirs based on pore distribution and T_2 spectrum

为了能够准确地计算低孔渗储层的渗透率,以渤海某油田低孔渗储层为研究对象,进行孔径分布对渗透率的影响研究。基于压汞孔径分布与核磁共振测井T_2谱均可以表征储层岩石的孔径分布信息,通过利用孔径分布直方图数据刻度核磁共振测井T_2谱数据,从而得到岩石不同孔径区间对应的T_2谱区间。通过渗透率贡献值确定各T_2谱区间每单位孔隙度分量的孔径对渗透率的贡献因子,最终建立基于孔径分布和T_2谱的低孔渗储层渗透率计算方法。结果表明,该方法避免了以往基于孔径分布的渗透率计算方法在划分T_2谱区间时的盲目性,以及根据经验确定不同区间贡献值的不可靠性。建立的基于孔径分布和T_2谱的渗透率模型对于低孔渗储层渗透率的评价有很好的指导作用。

To accurately calculate the permeability of low porosity and permeability reservoirs,we use a low porosity and permeability reservoir in an oilfield in Bohai to study the influence of pore size distribution on permeability. The pore size distribution information of reservoir rocks can be characterized based on the mercury penetration pore size distribution and the nuclear magnetic resonance（ NMR） logging T2 spectrum. The T2 spectrum data of different pore size intervals can be obtained by using the pore size distribution histogram data to calibrate the NMR logging T2 spectrum data. Permeability contribution values are used to determine the contribution factor of the pore size per unit porosity component to the permeability of each T2 spectral interval. A calculation method for permeability of low porosity reservoirs based on pore size distribution and T2 spectrum is then established. The results show that this method avoids the blindness of the previous calculation method of permeability based on the pore size distribution in the division of T2 spectral range,and avoids the unreliability of the contribution value of different intervals empirically determined. The established permeability model based on pore size distribution and T2 spectrum provides a good guidance to evaluate permeability of low porosity reservoirs.