Preparation and rheological properties of tannin extract gel for sealing steam channeling
The formation temperature of offshore heavy oil reservoir is low and steam channeling frequently occurs during steam flooding.In this paper,the tannin extract gel formed by using 6％bayberry tannin extract,0.2％urotropine and 3％clay has a controllable glue formation time at 55 ℃,high strength after heat treatment at 300 ℃,and dehydration rate of less than 5％after one month of heat treatment.Rheological analysis showed that the thixotropy of the extract and the strength of the extract after gelling were significantly enhanced by adding clay without increasing the viscosity of the extract.In addition,the tannin extract gels strengthened by clay can maintain the stability of the gel structure under large strain shear.The results of Cryo-SEM analysis of gels showed that the addition of micron clay particles could form multi-group cross-linked multi-network structures with the active hydroxyl of tannin extract molecules,which enhanced the water-locking ability of the gels,and is the reason for the increased stability of gels at high temperatures microscopically.The above experimental results showed that the tannin extract gel formed by strengthening clay particles have high strength and good thermal stability,which is suitable for the actual demand of steam channeling in the process of steam flooding in low-temperature reservoirs.
offshore heavy oil reservoirsteam channelingtannin extract gelrheological propertieslow temperature formed-gelthermal stability
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