概率法在煤层气储量估算中的应用

Application of probability method in coalbed methane reserves estimation

油气勘探过程中,地质储量的评估是非常重要的一项工作,而地质储量评估的关键在于对相关地质参数的把握。容积法是计算地质储量的常用方法,但是由于地质参数的不确定性,容积法对于地质储量的计算存在一定偏差。概率法储量估算以概率论为基础,视储量参数为一定范围内变化的随机变量,并要求参数之间相互独立。估算结果为一条储量概率分布曲线(或累计概率曲线),按规定概率值估算各类地质储量。本文研究用概率法分析煤层厚度、含气量、单点丰度分布形态等参数,通过概率统计的方式,结合沁水盆地一个开发后期的煤层气含气区进行储量评估,估算煤层气含气区不同风险值下煤层气地质储量。研究结果给出不同风险值下的煤层气储量,为勘探开发决策提供更好的技术支持。

In the process of oil and gas exploration,the evaluation of geological reserves is a very important work,and the key of the evaluation of geological reserves is to grasp the relevant geological parameters.Volume method is a common method to calculate geological reserves.However,the geological parameters are uncertain,there are some deviations in the calculation of geological reserves by volume method.Probabilistic reserve estimation is based on probability theory,which regards reserve parameters as random variables varying in a certain range,and parameters are independent.The estimated result is a probability distribution curve of reserves(or a cumulative probability curve),estimating all kinds of geological reserves according to the prescribed probability value.In this paper,the parameters of coal seam thickness,gas content and single point abundance distribution are analyzed by probability method.By means of probability statistics,combined with a coalbed methane gas bearing area in Qinshui basin at the later stage of development,the geological reserves of coalbed methane under different risk values are estimated.According to the evaluation results,the CBM reserves under different risk values are given,to provide better technical support for exploration and development decision-making.