恒速压汞在鄂尔多斯东南部致密砂岩储层中的应用

Application of Constant-Rate Mercury Intrusion in the Tight Sandstone Reservoirs of Southeastern Ordos Basin

为准确评价鄂尔多斯盆地东南部上古生界致密砂岩气藏孔喉分布特征,利用典型岩心的恒速压汞实验,研究了孔隙和喉道的分布特征以及孔喉半径比特征参数与孔渗间的关系,进而提出了喉道特征参数预测方法。结果表明:孔喉半径比峰值主要由喉道半径峰值决定,而孔喉半径比峰值比例主要受孔隙半径峰值比例影响;孔隙度受到孔隙和喉道的共同影响;渗透率主要由喉道特征参数决定,其中,喉道半径峰值对渗透率的影响最大;孔喉半径比平均值是同时影响孔隙度和渗透率的唯一参数。根据研究结果,建立了喉道特征参数预测模型,预测精度和敏感程度综合分析表明,预测结果可靠程度高。该项研究为准确评价鄂尔多斯盆地东南部上古生界致密砂岩气藏的孔喉分布提供了参考,实现了在未开展恒速压汞实验的情况下对喉道特征参数的准确预测,同时也为同类气藏的储层评价拓宽了思路。

Constant-rate mercury intrusion tests of typical core samples were carried out to accurately characterize the pore-throat distribution pattern of the Upper Paleozoic tight sandstone gas reservoirs in southeastern Ordos Basin.The pore-throat distribution pattern and the relationship between the characteristic parameters of pore-throat radius ratio and porosity-permeability were investigated to propose a method to predict the characteristic throat parameters.Result shows that the peak value of pore-throat radius ratio is mainly dependent on the peak of throat radius,and the peak proportion of pore-throat radius ratio is dependent on the peak proportion of pore radius.The porosity is controlled by both the pore and throat properties.The permeability is mainly influenced by the characteristic parameters of throat,and the most sensitive parameter is the peak of throat radius.The average pore-throat radius ratio is the only parameter influences both the porosity and permeability.According to the research result,a model was established to predict the characteristic parameters of throat.The accuracy and sensitivity analysis show a reliable prediction.This research could provide certain references for the accurate evaluation of the pore-throat distribution of the Upper Paleozoic tight sandstone gas reservoirs in southeastern Ordos Basin.This model could accurately predict the characteristic parameters of throat without constant-rate mercury intrusion experiment and also broaden the understanding for reservoir evaluation of similar gas reservoirs.