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鄂尔多斯盆地上古生界砂岩岩性气藏地质特征复杂，其储集层普遍具有低孔、低渗、低产特征，试气中很难发现绝对意义干层，使评价勘探与储量计算难度较大。本文通过对盆地上古生界典型砂岩岩性气藏勘探历程的回顾，结合评价勘探生产与储量计算实践，认为大型砂岩岩性气藏在评价勘探中要重视地震储层横向预测技术的应用，在勘探阶段，地震网测密度可适当放宽，探井井距保持在复合砂体1/2一1/3之间。同时对该类气藏在储量计算中合气面积圈定、有效厚度产气量下限确定、孔隙度计算和合气饱和度等关键参数的求取方法进行了探讨。

Research on the Evaluation Exploration and Reserve Calculation Metho ds of Lithologic Gas Reservoirs

??The geological features of the sandstone lithologic gas reservoirs in Upper Paleozoic in E'erduosi Basin are complicated and their reservoir beds are commonly possessed of the characteristics of low-porosity,low-permeability and minor-production,an absolutely lean gas reservoir being difficult to be discovered in well testing,which increases the difficulty in doing evoluation exploration and reserve calculation.On the basis of studying the exploration process of the typical sandstone lithologic gas reservoirs in Upper Paleozoic the basin and in combination with the practice of evaluation exploration,production and reserve calculation,it is considered that the application of seismic reservoir lateral prediction technique in evaluation exploration of giant sandstone lithologic gas reservoirs must be highly thought of;and in exploration stage,the seismic line density may be properly widened and the exploration well spacing is 1/2??1/3 the diameter of composite sandstone body.Meanwhile,the methods of acquiring these key parameters as gas-bearing area,effective pay thickness cutoff,porosity and gas saturation,etc.,in reserve calculation for this kind of gas reservoir are discussed in the paper.