油井产能评价是通过产能测试完成的。 常规的产能测试是在地下进行的，即通过测量油井产量和井底压力来确定油井的产能指数，从而对油井产能做出评价。 对于某些油井，井底压力测试十分困难，产能评价往往难以实现。 为了有效评价油井的产能，对其评价方法进行了改进，即把产能测试从地下移至地面，通过测试油嘴的产能方程来评价油井的产能，并采用油嘴产能指数的大小来评价油井产能的高低。通过测量不同油嘴大小的油井产量，即可确定油嘴产能指数。 研究表明，油嘴产能测试不影响油井的正常生产，也不增加任何测试费用，方法简单、实用。

Productivity evaluation of wells is completed through productivity test of wells. Conventional productivity tests are accomplished at well bottom through measuring production rate and flowing pressure of well bottom in order to determine the productivity index of wells. Productivity index is a parameter to evaluate productivity of wells. However, some wells are difficult to measure their bottom pressure and the productivity index cannot be obtained. In order to evaluate the productivity of wells effectively, productivity evaluation method was improved with measurement at wellhead other than at well bottom. Test of well productivity at wellhead is completed through the determination of nozzle flow equation, which can determine the nozzle productivity index to evaluate the productivity of wells. The nozzle productivity test is completed through measuring flow rate of wells and the size of choke nozzle, which can calculate the nozzle productivity index. The nozzle productivity test can be done simultaneously with the production of wells without any negative effect on the production of oil and gas and any additional cost. Nozzle productivity test is quite simple and practical to the conventional test at well bottom.