低压、小产气井自生气药剂泡沫排水技术及其应用

针对四川盆地中部地区上三叠统须家河组气藏低压、小产气井积液后排液困难的问题，将井下化学产气技术与起泡剂排水技术复合应用，利用自生气药剂的产气作用使井底压力达到起泡剂排水所需启动压力，并使起泡剂与积液快速、充分混合，改善了气井排水能力，形成了适合低压、小产气井的自生气药剂泡沫排水技术。采用多种产气物质复配物作为自生气药剂，其产气量最高可达160 mL/g，抗盐能力可达200 g/L。高温、低pH值有利于自生气药剂产气反应的进行，现场可以通过调节pH值来控制自生气药剂的产气量；采用一种两性离子表面活性剂作为起泡剂，在70℃、10%凝析油条件下，起泡能力可达109 mm，携液能力可达135 mL。现场应用表明，２口低压、小产气井采用自生气药剂泡沫排水技术获得了成功，快速将积液排除，提高了日产气量和产水量，转入普通泡沫排水作业后能维持正常排水生产。该排水技术为积液气井的排水作业提供了一种新方法。

Foam drainage technology by use of a self-foaming agent and its application in low-pressure and low-yield gas wells

The drainage of accumulated fluids is a difficult problem for low pressure and low yield gas reservoirs of the upper Triassic Xujiahe Formation in the Sichuan Basin. In view of this, a composite technology is applied combining the technologies of downhole chemical gas generation and the foaming agent drainage. The gas generated from the self foaming agent is used to make the downhole pressure up to the starting pressure as required by the foaming agent drainage; the foaming agent can be mixed with the accumulated fluids rapidly and completely, thus to improve the drainage capacity and to complete a process of self generating drainage for low pressure and low yield gas wells. The self foaming agent is a compound of multiple gas producing substances, with a maximum gas output of 160 mL/g and salt tolerance of 200 g/L. Besides, high temperature and low pH value facilitate its gas production. Therefore, pH value can be adjusted on site to achieve a higher yield of this gas agent. In addition, a zwitterionic surfactant is used as the foaming agent; its foaming ability and liquid carrying capability can reach 109 mm and 135 mL respectively under the condition of 70℃ and 10% condensate oil. In case histories, the self foaming drainage technology has been successfully implemented in 2 low pressure and low yield gas wells. The accumulated fluids were drained so quickly that daily gas output and water output were both increased. Moreover, normal drainage and production were also able to be maintained after the production was switched to regular foaming drainage operation. In conclusion, this technology provides a new method for water drainage of the gas wells with accumulated fluids.