| As we know, the stratum temperature of Jidong Oilfield, Tuha Oilfield and other oildeposits that have high temperature is generally90to120℃in our country. Besides, thesestratums are always in high water cut stage. Current profile control agents are mostly subjectto temperature, total dissolved solids and layer cutting so that they often degrade and loseeffect. For instance，Tarim Oilfield shaft bottom has a circulate temperature about110℃andthe majority are horizontal wells. What is more, the current profile control agents is difficultto meet the needs of on-site construction. Therefore, the development of late-acting hightemperature deep profile control agent can be a fundamental solution to the problem of "shortcircuit" of oil deposit’s water driving, which has high temperature and high content water.Nowadays chromium gel is the most widely used, whose colloidal viscosity and shearresistance can be profile and block effectively. However, chromium gel does not have a goodstability of heat and will raise its dehydration degradation rate when it encounter thetemperature above100℃. In addition, the heavy metal ion must pollute groundwaterseriously. Consequently, the development of resistance to high temperature and a longer termof validity is of great significance for deep profile control agent.We choose polyacrylamide that is most widely used in the spot as the primary agent andchoose Aluminum citrate and phenolic aldehyde as the crosslinking agent. We investigate thefluid viscosity, temperature resistance, salt tolerance and gel properties of the two profilecontrol system to determine the best gelation conditions; we will pick out the concentrationrange of the two crosslinking agents that have a longer time in gelation and use the twocrosslinking agents respectively in order to determine the conditions of the the composite gelinto plastic and investigate the performance in the end.The results of the research showed that: when reaching the temperature under60℃，thesystem that consists of the polyacrylamide solution1500mg/L and0.12%of the phenoliccrosslinking agent profile is adjustable from1to5days in gelation time. At the same time, ithas a viscosity of7000to9000mPa·s. What is more，The system can be applied in thecondition that high-salt (less than14000mg/L) and strata in the pH=3to7of thehigh-temperature (less than155℃) exist and will not dehydrate and degradate during60days;when reaching the temperature under60℃and the pH=7,1500mg/L polyacrylamidesolution and0.18%of lemon acid aluminum cross-linking agent will gelatinize during1to5days. Furthermore, the time is controllable and it will have a viscosity of7500to8500mPa·s,when reaching the temperature under105℃，the system will have a good thermal stabilityand a maximum resistance to salinity12000mg/L; When reaching under60℃,1500mg/L ofthe polyacrylamide solution and the composite-type crosslinking agent (phenol: aluminum citrate=4:1to6:1) may be prepared as a controllable composite gel system that has a gelationtime within120h, moreover, its final viscosity is greater than12000mPa·s, and thetemperature resistance can reach190℃, when the total dissolved solids reach under16000mg/L; for the heterogeneous core100~120mD, composite gel can greatly reduce itspermeability, the plugging rate was more than90%, and improve the recovery rate of morethan3.2%. The scope of application of composite gel is very wide, the system sometimeschanges the proportion of cross-linking agent to apply to the deep profile control (drive)operations in different high-temperature and high-salinity oil deposit. |
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