当抽油井流压低于原油饱和压力时，环空中由于气体从油中分离出来而产生泡沫段，从而失去明显的油气界面，无法采用回声仪测试油井的真实液面。根据物质平衡方法设计的拟液面测试仪，可通过测试油井环空排气量来确定油井的真实液面。现场测试表明，该方法比回声仪测试法减少误差10％以上。 When the pumping well flow pressure is lower than the saturation pressure of crude oil, the bubbles in the annulus are separated due to the separation of the gas from the oil. As a result, the obvious interface between the oil and gas is lost and the real surface of the oil well can not be tested by the echo meter. The quasi-level tester designed according to the material balance method can determine the actual level of the oil well by testing the annulus displacement of the well. Field tests show that the method is less than 10% error reduction than the echo test method.