致密砂岩气储量不确定性计算方法及意义

Uncertainty reserves calculation for tight sandstone gas and its significance

致密砂岩气藏储层非均质性强、厚度变化快,空间准连续分布,含气面积难确定。为了解决当前致密气资源评价与储量计算方法存在的局限性问题,提出不确定性计算方法,并对鄂尔多斯盆地A地区盒2段致密砂岩气地质储量进行评价。结果表明:利用地质统计学随机模拟算法对储量计算参数进行随机模拟,采用不确定性容积法分阶段计算不同探井数时不同概率下的地质储量,可以有效识别饱和勘探点,降低勘探成本和地质风险,最大效益化整个气田的勘探开发过程;计算同一概率条件下储量丰度,按照分级评价、"好带差"的开发理念,可优先选择计算储量至少有90%可靠性的资源进行开发,有效指导开发节奏。不确定性容积法计算地质储量对致密砂岩气资源的健康、合理、有序的勘探开发具有重要指导意义。

Based on the quasi-continuous distribution of tight sandstone gas reservoirs,the difficulty in determining the gas-bearing area,the strong heterogeneity of reservoirs and the rapid change of thickness,in order to solve the limitations of current tight gas resources evaluation and reserves calculation methods,an uncertainty volume method is proposed.Taking Member He-2 in the A area of the Ordos Basin as an example,the geological reserves of tight sandstone gas were calculated,and its significance of exploration was expounded.The results show that using the geostatistics stochastic simulation algorithm to randomly simulate the reserves calculation parameters,and then the uncertainty volume method to calculate the different probabilistic geological reserves under different exploration well numbers in different stages,the saturated exploration point can be effectively identified,and the exploration cost and geological risks are reduced,maximizing the exploration and development process of the entire gas field.According to calculating reserves abundance under the same probability condition and considering classification evaluation and the development concept of"first the good area and second the bad area",the geological resources of P90 in sweet spot should be preferentially developed.This method could guide the development rhythm effectively.Using uncertain probability volume method to calculate geological reserves has important guiding significance for the healthy,reasonable and orderly exploration and development of tight sandstone gas resources.