液体胍胶非水悬浮液的制备与水合性能

Preparation and Hydrating Property of Non-Aqueous Guar Concentrated Suspensions

采用羟丙基胍胶、聚乙二醇及悬浮剂等制备了液体胍胶非水悬浮液,分别考察了液体胍胶非水悬浮液的表观黏度、悬浮率及水合速率,进一步探讨了该液体胍胶体系快速水合起黏的影响因素。流变及静置沉降实验结果表明,季铵盐改性的有机黏土适合作为液体胍胶的悬浮剂,液体胍胶的黏度随悬浮剂加量的增加而轻微增加,且其悬浮率随该悬浮剂加量的增加而急剧增大。悬浮剂加量为5%的液体胍胶在340 s-1下的表观黏度为650m Pa·s左右,在1 d内基本不沉降,在2 d内的悬浮率能够保持在98%以上。粉液比(胍胶与聚乙二醇的质量比)在1∶5~1∶2之间时,其对应的液体胍胶于340 s-1下的表观黏度值在200~700 m Pa·s之间,具备较好的流动性,便于连续混配设备泵送。水合起黏实验结果表明,与在中性环境下相比,弱酸性环境下采用该液体胍胶配制的压裂液基液具有更快的水合起黏速率,而碱性环境下该压裂液基液基本不起黏。配液用水pH值为5时,基液黏度在3~5 min内即达到最佳基液黏度的85%~90%。配液时采用高剪切循环速率会加快液体胍胶的起黏速率。

In this paper,non-aqueous liquid guar concentrated suspensions(NALGCS)were prepared by mixing hydroxypropyl guar gum,polyethylene glycol and suspending agent. Apparent viscosities,suspension ratio and hydration rates of the NALGCS were evaluated and the influencing factors of quick hydration of the NALGCS were further discussed. Results of rheological experiments and settlement observations showed that quaternary ammonium salt modified montmorillonite was suitable as a suspending agent of the NALGCS. With the increase of the suspending agent content,apparent viscosities of the NALGCS slightly increased,and suspension ratio sharply increased. The apparent viscosity of the NALGCS with 5% of the suspending agent was about 650 m Pa·s at shear rate of 340 s-1,the suspension ratio was approximate 100% within 1 d and above 98% within 2 d.Apparent viscosities of the NALGCS with powder liquid ratio(mass ratio of guar gum to polyethylene glycol solution)of 1:5—1:2was 200—700 m Pa·s at shear rate of 340 s-1,indicating that the NALGCS possessed good flowability,moreover,it was beneficial to pump guar concentrated suspensions into continuous mixing vehicles. Results of hydration experiments showed that a quicker hydration rate of fracturing base fluid prepared using the NALGCS was found under the condition of weak acid,comparing with under the condition of neutral environment,however,the NALGCS could not hydrate under alkaline condition. The p H value of the dosed water was 5,the 85%—90% of maximum viscosity of the base fluids was achieved within 3—5 min. Higher shear rate would also accelerate hydration of guar concentrated suspension.