【摘要】 研发了适用于高温低渗油田调剖堵水的改性落叶松栲胶堵剂。基础配方(以质量计)为:6.0%磺化落叶松栲胶+2.5%~3.0%甲醛+1.0%~1.5%促进剂+水,pH值8~10。基础配方堵剂溶液25℃、3500 1/s黏度为1.5mPa.s;温度由120℃升至180℃时,成胶时间由7.5 h缩短至约4 h;从成胶时间和代表凝胶强度的突破真空度确定其适用的pH值范围为4~10;外加NaCl特别是CaCl2使其成胶时间缩短,突破真空度在NaCl加量≤50 g/L时下降幅度很小,NaCl加量为100 g/L时仍不低于66 kPa。减少任一组分用量而保持其他组分用量不变,均使堵剂溶液成胶时间缩短,通过改变各组分用量和加盐量可在很大范围内调节堵剂溶液的成胶时间。堵剂在120℃放置48h后质量变化小于5%,在180℃放置120 h后质量变化小于8%。堵剂凝胶在250℃的5%盐酸、5%苛性钠、10%NaCl溶液中至少可稳定存在6 h。加入原油量超过10%的堵剂溶液不能成胶,因而该堵剂有一定选择性。在2支填砂管封堵实验中,封堵率为98.5%和97.6%,突破压力梯度为25.3和36.4 MPa/m。讨论了栲胶与甲醛的交联反应。图7表1参5。更多还原

【Abstract】 A modified larch tannin extract(MLTE)/formaldehyde (FA) gelling solution is developed for injectivity profile modification/water plugging in high temperature,low permeable oil reservoirs.Its basis recept is composed of 6.0% MLTE,2.5—3.0% FA,and 1.0—1.5% crosslinking promotor in water solution with pH value adjusted to 8—10.This gelling solution has viscosity of 1.5 mPa·s at 25℃ and 3500 1/s,its gelation time decreases from 7.5 to ～4 hrs when the crosslinking temperature is raised from 120℃ to 180℃;it can be used at pH value ranged in 4—10 as shown by gelation time and breakthrough vacuum (representing gel strength) measurements;NaCl and,in particular,CaCl2 added shorten its gelation time in general and its breakthrough pressure decreases a little at NaCl dosage ≤50 g/L and keeps a value of 66 kPa at NaCl dosage=100 g/L.Reducing mass fraction of an ingredient in the gelling slution and keeping invariable mass fraction of other two always lead to shortening its gelation time, which can controlled in a large range through changing mass fraction of ingredients and salinity.The change in mass of the gelled solution is within 5% after ageing at 120℃ over 48 hrs or within 8% after ageing at 180℃ over 12 hrs.The gelled solution is stable in 5%HCl,5%NaOH,and 10%NaCl solutions at 250℃ at least in 6 hrs.The gelling solution with more than 10% crude oil added can not gelatinate and thus it is a selective plugging agent.On two sand packs a plugging rate of 98.5% and 97.6% and a breakthrough pressure gradient of 25.3 and 36.4 MPa/m are obtained with the gelling solution.The crosslinking reactions of tannin extract with formaldehyde are presented.更多还原