页岩含气量计算新方法

A new method to calculate the shale gas content

通过分析常规页岩含气量测试所面临的问题,从页岩含气量本质入手,提出了利用绝对吸附量计算含气量的可行性方法。通过假设吸附相体积与比表面积间的关系及孔隙中密度分布最小值与体相密度之间随着压力的变化关系,提出了页岩含气量计算的新方法,并借助简化局部密度函数理论和页岩实测等温吸附曲线实现了页岩含气量的计算。研究发现:简化局部密度函数理论可以精确拟合页岩等温吸附曲线,说明该理论可以有效地描述页岩的吸附特性;利用简化局部密度函数理论及页岩等温吸附曲线可实现页岩含气量的计算,该方法的优势在于基本上能够还原储层温度、压力下气体在页岩中的原始赋存状态。

Through analyzing problems of the conventional tests on gas content of shale,a feasible method was proposed to calculate gas content in shale using absolute adsorption.With the assumption of the relation between adsorption phase volume and specific surface area as well as change of the least density distribution and bulk-phase density in pores with pressure,a new method was put forward to calculate the gas content of shale.The gas content of shale was calculated via the simplified local density function theory and the adsorption isotherm of shale.Results indicate that the simplified local density function theory can be used to precisely fit the adsorption isotherm of shale.This method presents an advantage in basically restoring the original occurrence state of gas in shale under reservoir temperature and pressure.