Research And Application Of Cation Blocking Agent At High Temperature And Salinity Tolerance In Shengtuo Oilfield

During the high water cut stage of Shengtuo oilfield, water shutoff and profile control technology gradually became one of the main technology to inhibit moisture to increase. But there are still many problems about blocking agent used in Shengtuo oilfield. On one hand, blocking agent can hardly meet the profile control requirment of the high-temperature and salsuginous reservoirs,such as the T142 block, in which,the reservoir temperature is 99.8℃, the salinity is 53897 mg/l, and the average air permeability is 50×10^-3μm². This block has been exploired through waterflood in the year 2001, and now the water cut is up to 80%, with serious water channeling problem. The sensitivity of the particles blocking agent is strong to reservoirs, and in low permeability reservoirs, the block agent is prone to return back. Temperature and salinity tolerance of chromic gel blocking agent is poor, which can not meet the profile control needs of T142 Block.On the other hand, adsorption capacity of the gel block agent used is weak. As a result, sand came out and blocking agent returned in several wells after plugged, which has seriously affected water shutoff efficiency. In view of the above problems, cationic gel plugging agent with high temperature and salinity tolerance has been developed through experiments. Compared with conventional gel blocking agent, the adsorption capacity of this agent is strong, and it can meet the profile control requirment of the high-temperature and salsuginous reservoirs.Through the indoor experiments and numerical simulation, the rational injection process has been decided. After the agent is applied in the T142 block, obvious effect has been achieved to control water cut. This agent is used in oil wells for water shutoff and has prevented the return of blocking agent effectively, which improves the success rate of water shutoff, and has important significance on the exploitation of high-temperature and salsuginous reservoirs and the enhancement of water shutoff effect in Shengtuo oilfield .