Objective Aiming to effectively solve the problems of severe scaling in the wellbore of the gas lift drainage well in the Longwangmiao Formation gas reservoir of Moxi block, short effective time for acidification to remove blockages, and difficulty in ensuring the effectiveness of corrosion and scale inhibitors in high-temperature environments, the high-temperature corrosion and scale inhibitor optimization and on-site testing were carried out to extend the gas well blockage cycle and ensure stable drainage of the gas well.

Method In response to the dynamic characteristics and blockage status of gas well production, scaling prediction software was used to simulate wellbore scaling. Based on this, indoor tests were conducted on compatibility with water, calcium carbonate scale inhibition performance evaluation, calcium carbonate scale and corrosion inhibition performance evaluation under operating conditions,and optimized the compound of organic phosphine carboxylic acid C and pH regulator, and scale inhibition field tests were carried out in Well A.

Result Indoor performance evaluation experiments showed that the compound of organic phosphine carboxylic acid C and pH regulator had good corrosion and scale inhibition performance. At high temperature (140 ℃) and high mineralization (110 g/L) conditions, the scale inhibition rate was 49%, and the corrosion rate was 755 g/(m²·h). After on-site corrosion and scale inhibition tests in Well A, the unblocking period was extended by 50 days, and the stage drainage increased by 26 651 m³, the daily drainage showed a slow upward trend, and the drainage effect was good. The annual operating cost was saved by 3.6 million yuan, with good economic benefits.

Conclusion The scale inhibition process using organic phosphine carboxylic acid C and pH regulator compound corrosion and scale inhibitor effectively delays wellbore scaling and blockage, ensures the drainage effect of gas wells, and provides technical support for delaying water invasion trend and maintaining stable production in gas reservoirs. It is suitable for scale inhibition in the same type of perforated gas lift drainage wells or other high temperature high-yield water wells.