弹性二相法是评价气井控制原始地质储量的动态法，又称为拟稳态法（pseudo-steady-state method）或气藏范围测试法（reservoir limit testing method）。该法主要用于气井初期测试，评价岩性、断块和裂缝类型气藏井控的原始地质储量。由压力平方表示的弹性二相法，在中国从1994年起，连续4次被列入国家油气行业标准（SY/T 6098—1994，SY/T 6098—2000，SY/T 6098—2010，SY/T 6098—2022）。与拟压力表示的弹性二相法相比，由压力平方表示的弹性二相法是一种较好的近似评价方法。利用AL-HUSSAINY（1966）指出的拟压力关系式，经理论推导，得到了拟压力的弹性二相法，并应用WATTENBARGER（1968）对μ_gZ随p的变化关系研究，对拟压力弹性二相法进行了简化，分别得到了由压力一次方和压力平方表示的弹性二相法。目前，在国内外的文献中，尚看不到有关拟压力弹性二相法推导的报道。通过实例应用表明，压力一次方表示的弹性二相法评价的井控原始地质储量明显偏低，而由压力平方表示的弹性二相法评价的结果明显偏高。

The elastic two-phase method, also known as the pseudo-steady-state method or reservoir limit testing method, is a pivotal dynamic technique for estimating the original gas in place（OGIP）in well-controlled scenarios. This method is primarily employed in the initial testing of gas wells and for the OGIP assessment in varied lithologies, fault blocks, and fracture types of gas reservoirs. Since 1994, the pressure squared variant of this method has been recognized in the Chinese national oil and gas industry standards across four editions: SY/T 6098—1994，SY/T 6098—2000，SY/T 6098—2010，SY/T 6098—2022. This method, based on the pressure squared calculation, offers a robust approximation compared to its pseudo-pressure counterpart. The theoretical derivation of the elastic two-phase equation for pseudo-pressure, originally proposed by AL-HUSSAINY（1966）, and further simplified using WATTENBARGER's（1968）study on the relationship between μ_gZ and p, allows for representations using both pressure to the first and second powers. Notably, while the pressure to the first power method tends to under-estimate OGIP, the pressure squared method is inclined to over-estimate, as evidenced by practical applications. Currently, there is a lack of substantial literature on the pseudo-pressure elastic two-phase method both domestically and internationally.