致密气资源评价与储量计算方法研究

致密砂岩气是我国非常重要的一类非常规油气资源,但针对致密气资源储量计算方法的相关规范或标准至今尚未出台。本文在简要对比非常规油气与常规油气资源评价方法基础上,对现阶段致密砂岩气资源评价方法进行讨论,针对致密砂岩气藏特性,提出了适用于致密气储量计算的不确定性容积法。研究表明,考虑到致密砂岩气藏空间准连续分布、含气面积难确定、有效厚度与储层物性参数非均质性强的特点,利用不确定性的概率容积法计算致密砂岩气地质储量更为科学;以鄂尔多斯盆地康宁地区盒2段为例,利用地质统计学随机模拟算法计算得到P90、P50、P10不同概率地质储量;按照完井时间顺序依次计算不同探井数时地质储量,发现地质储量计算结果与已钻井数有关,在达到饱和勘探点之前应采用不确定性概率容积法计算地质储量,降低勘探风险。利用不确定性概率容积法计算地质储量有利于致密砂岩气资源的健康有序勘探开发。

Study on resources evaluation and reserve calculation method of tight gas

Tight sandstone gas is very important type of unconventional oil and gas resources, but the relevant industry standards or regulations for tight gas reserves estimation has not yet introduced. Based on a brief comparison of resource evaluation methods of unconventional oil and gas and conventional oil and gas, and a discussion on tight sandstone gas resource evaluation methods at present, this paper puts forward an uncertainty volume method for tight gas resource estimation. The results show that, considering tight sandstone gas reservoirs characteristics of quasi-continuous spatial distribution, difficulty in determining gas-bearing area, and the strong heterogeneity of the effective thickness and reservoir parameters, it"s more scientific to estimate tight gas geological reserves using uncertain probability volume method. Taking He-2 member in Kangning area of Ordos Basin as an example, by using geostatistics stochastic simulation, P90, P50, P10 probability of different geological reserves are calculated based on volume method. The geological reserves are estimated in different exploration well numbers in accordance with the completion time order, which shows the reserves estimation results have been related to the drilled well number, for reducing exploration risk, the uncertain probability volume method should be used to calculate tight gas geological reserves before reaching the saturation exploration point. Using uncertain probability volume method to calculate geological reserve is benefit to tight sandstone gas resources healthy and orderly exploration and development.