Development And Evaluation Of Temperature And Salt Resistance Konjac Gum Profile Control Agent

Gasikule E31 reservoir is high temperature and high salinity reservoir,its average temperature is 126 degrees and average salinity of formation water is 10.5×104mg/L.The reservoir has strong heterogeneity with its residual oil dispersed in water,leading to serious water channeling during water flooding process and lower water flood sweep efficiency.Besides,due to high temperature and high salinity,the common plugging agent is easily to break and degradation,this phenomenon is difficult to play a significant role.Based on the sufficient study of profile control technology of high temperature and high salinity reservoir,it is proposed to use konjac powder as the main agent research of temperature resistant and salt resistant agent system,and the profile control agent were evaluated systematically.Core flow experiment have shown that the best formula of the profile control agent system in freshwater is crude konjac powder concentration 5.0g/L+suspensions concentration700～1000mg/L+crosslinking agent volume fraction 0.5%～1.2%+oxygen scavenger 100-200mg/L.And the optimum formula of formation water is crude konjac powder concentration 5.Og/L+suspensions concentration700～1000mg/L+crosslinking agent volume fraction 1.0%～1.2%+oxygen scavenger 100～200mg/L.The profile control agent has good temperature resistance,salt resistance and good long-term stability under high temperature condition,which can be well adapted to high temperature and high salinity reservoir environment.After gelling in the formation temperature for 120d,gel shows stability with only a small amount of dehydration and the strength remains unchanged.The profile control agent has good long-term stability under different high temperature conditions.When the fluid salinity below the salinity of formation water,the concentration of NaCl is lower than 80000mg/L,CaCl2 concentration lower than 5000mg/L,MgCl2 concentration lower than 1600mg/L,the gel strength is high,and the performance is stable.When the pH value is too low or too high is not conducive to the profile control agent,Suitable for konjac powder profile control agent pH is in the range of 6-10.Core flow test show that The konjak gel profile control agent has good injection performance before gel;when inject 0.5PV profile control agent,sand filling tube plugging rate reached 99.2%,indicating that the profile control agent has good sealing performance for micro porous props;After the gel profile control agent,continuous water flooding 12PV,The plugging rate of sand filled pipes is still 93.0%,so the profile control agent resistant erosion performance good.The parallel core flow experiment show that profile control agent has preferably chosen performance into high permeability layer,after profile control,core profile improvement rate was91.5%～97.0%.The low permeability sand filling tube increased 16.3%～26%recoveries.The high permeability reservoirs sand filling tube increased 4.3%～9.6%recoveries.Single round profile control and Stage multi rounds of profile control experiments showed that Single rounds after profile control is to improve the recovery rate was 12.2%,multi round profile control after a total increase recovery rate was 13.1%,multi round profile control is more conducive to enhance oil recovery.The results of this study have important significance for improving the high temperature and high salinity reservoir water flooding.