页岩气地质储量计算新方法

A new method to calculate shale gas geological reserves

页岩气是一种重要的非常规能源,资源丰富,具有良好的勘探开发前景。页岩气主要由游离气、吸附气2个部分组成,其中吸附气储量可利用测试数据,通过Langmuir等温吸附曲线计算,而游离气储量常采用容积法计算,众多学者在计算过程中忽略了吸附气占据的孔隙体积,因而得出的游离气储量往往偏大。首先给出了利用线性回归确定兰氏压力和兰氏体积的方法;然后通过引入平均分子自由程,从单个吸附相分子所占体积入手,计算出吸附相占据的总体积,最终推导出除去吸附相体积的游离气储量计算方法。通过实际数据和Ambrose提出的方法进行了对比,验证了该方法的可靠性。最后,分析了基质吸附能力、地层温度和压力对页岩气储量计算结果的影响。

Shale gas is an important unconventional energy,which has a good development prospect due to its rich resources.Shale gas mainly consists of free gas and adsorbed gas.Adsorbed gas reserves can be calculated by Langmuir isothermal adsorption curve,and free gas reserves can be calculated by volume method.However,the pore volume occupied by the adsorbed gas is always ignored in the process of free gas reserves calculation,thus the result of free gas reserves is often larger than its actual value.First,this paper provided a method of linear regression to determine Langmuir Volume and Langmuir pressure;then by introducing the mean free path of molecules,we calculated the volume of single molecules volume in adsorbed phase and got the total volume of adsorbed gas,ultimately derived the free gas reserves removing adsorbed phase volume.In addition,by comparing with Ray J.Ambrose＇s method using actual data,reliability of the new method was verified.Finally,this paper analyzed the impact of matrix absorption capacity,formation temperature and pressure on the calculation of reserves.