Water shut-off pilot test at a deep well with high temperature and bottom water in Shixi oilfield

A successful water shut-off pilot test was carried out at a deep production well with high temperature and bottom water in the Carboniferous reservoir of Shixi Oilfield.After the water shut-off treatment had been made in the reservoir for 189 days,the cumulate liquid production decreased by about 3159 tons,and the cumulate oil increment reached about 570 tons.The liquid production per day gradually reduced from 105 tons to 78 tons after treatment for three months.A new method of three-section plugging was used to deal with the harsh reservoir conditions.The temporary plugging agent,main slug (surfited larch tannin extract) and sealing cement were injected into the reservoir separately.The injected temporary plugging agent could seal the zones for about 15 hours,and then the main slug of water shut-off agent gets into the water zones selectively.The formed gel of plugging agent with the surfited larch tannin extract may resist high temperature at bottom hole and have a good thermal stability.The slug of sealing cement could enhance the strength of the water shut-off agent.