海水中瓜尔胶溶胀性能研究

Swelling Performance of Guar Gum in Seawater

针对海上连续混配海水基压裂液过程中稠化剂溶胀问题,开展了瓜尔胶溶胀性能的研究。考察了瓜尔胶取代基类型、取代度、搅拌速度、瓜尔胶加量、pH值和温度对瓜尔胶溶胀性能的影响。结果表明,我国某海域海水水样矿化度为34440 mg/L,富含Na+、Mg2+、Ca2+和Cl-、SO42-。在常规条件下(20℃、300 r/min、pH=7.5),羧甲基瓜尔胶、羟丙基瓜尔胶(取代度0.30)、羟丙基瓜尔胶(取代度0.15)、未改性瓜尔胶在海水中的溶胀时间分别为25、50、55、60 min,对应的表观黏度分别为63、59、45、23 mPa·s。以羧甲基瓜尔胶为研究对象,考察了其他因素对溶胀性能的影响。优选的配制方案为:搅拌速度400~500 r/min、温度30~40℃、pH值6~7,瓜尔胶加量0.5%以内。溶胀时间能控制在10min以内,满足连续混配海水基压裂液施工要求。

There was swelling problem of thickening agent when the fracturing fluids prepared with seawater was continuously mixed during the offshore hydraulic fracturing operation. So the research on the swelling performance of guar gum was conducted.The effect of the type of modified group,the degree of molar substitutions,stirring speed,guar gum concentration,pH value and temperature on swelling performance of guar gum was studied. The results showed that the seawater sample was rich in Na+,Mg2+,Ca2+,Cl-and SO42-with 34440 mg/L salinity. Under conventional conditions such as 20℃,300 r/min and 7.5 pH value,the swelling time of carboxymethyl guar gum,hydroxypropyl guar gum(DS=0.3),hydroxypropyl guar gum(DS=0.15)and unmodified guar gum was 25,50,55 and 60 min,and the corresponding apparent viscosity of that was 63,59,45 and 23 mPa·s. The effect of other factors on swelling performance of carboxymethyl guar gum was studied and the optimum preparation condition was obtained as follows: 400—500 r/min stirring speed,30—40℃ temperature,6—7 pH value and dosage of guar gum within 0.5%. The swelling time could be optimized within 10 min to meet the requirement of continuously preparing seawater-based fracturing fluids.