热采井耐高温低密度水泥浆体系研究
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摘要
针对稠油油藏埋藏浅且地层的破裂压力较低的特点,基于晶体化学中的紧密堆积排列理论,设计了一套耐高温低密度水泥浆体系。该体系以玻璃漂珠为减轻剂,碳纤维为增韧剂,具体配方以G级水泥为基础,其他添加剂加量(w)为:35%硅粉+2%膨胀剂Bond+76.7%淡水+6%降滤失剂CG88L+2.4%分散剂CF44L+8%填充剂MX+3%增强剂STR+1%消泡剂CX601L+0.6%缓凝剂H21L+28%漂珠+0.3%增韧剂XW-3,该水泥浆体系密度为1.4 g/cm~3。室内试验评价结果表明:该体系的水泥具有良好的韧性,其80℃养护24 h的抗冲击强度可达1.91 kJ/m~2,抗压强度25.8 MPa,API静态滤失量37 mL,稠化时间195 min。水泥石在经过350℃的超高温养护7 d后,其强度依然有20.5 MPa。说明该低密度体系水泥耐高温性极好,满足固井作业的基本需求。
In view of the low buried pressure of the heavy oil reservoir and the low fracture pressure of the formation,a low density cement slurry system with a density of only 1.4 g/cm~3 is designed based on the compact packing theory in crystal chemistry. The system uses hollow floating beads as density reduce agent and carbon fiber as toughener,and the formula is based on G-grade cement,the dosage( mass fraction) of other additives is determined as follows: 35% ganister sand + 2% expanding agent Bond + 76.7% fresh water +6% filtrate reducer CG88L + 2.4% dispersing agent CF44 L + 8% filler MX + 3% strength agent STR + 1% defoaming agent CX601L+ 0.6% retarder H21L + 28% floating bead + 0.3% toughener XW-3. The laboratory evaluation results show that the cement of this system has good toughness,its impact strength at curing at 80 ℃ for 24 hours can reach 1.91 kJ/m~2,API water loss is 37 mL,and the thickening time control can be around 195 min. After 7 days of ultra-high temperature curing at 350 ℃,the strength of cement stone is still 20.5 MPa,which is only slightly weaker than that at 80 ℃ for 24 h. It shows that the low density cement has excellent high temperature resistance and meets the basic needs of cementing operations.
In view of the low buried pressure of the heavy oil reservoir and the low fracture pressure of the formation,a low density cement slurry system with a density of only 1.4 g/cm~3 is designed based on the compact packing theory in crystal chemistry. The system uses hollow floating beads as density reduce agent and carbon fiber as toughener,and the formula is based on G-grade cement,the dosage( mass fraction) of other additives is determined as follows: 35% ganister sand + 2% expanding agent Bond + 76.7% fresh water +6% filtrate reducer CG88L + 2.4% dispersing agent CF44 L + 8% filler MX + 3% strength agent STR + 1% defoaming agent CX601L+ 0.6% retarder H21L + 28% floating bead + 0.3% toughener XW-3. The laboratory evaluation results show that the cement of this system has good toughness,its impact strength at curing at 80 ℃ for 24 hours can reach 1.91 kJ/m~2,API water loss is 37 mL,and the thickening time control can be around 195 min. After 7 days of ultra-high temperature curing at 350 ℃,the strength of cement stone is still 20.5 MPa,which is only slightly weaker than that at 80 ℃ for 24 h. It shows that the low density cement has excellent high temperature resistance and meets the basic needs of cementing operations.
引文
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[2]姚晓,李华,王玉军,等.耐高温低密度油井水泥的研究及应用[J].南京工业大学学报(自科版),2003,25(5):24-27.
[3]刘艳红.高温低密度水泥浆研究[D].北京:中国石油大学(北京),2001.
[4]徐伟祥,王成文,刘巍,等.新型抗高温粉煤灰低密度水泥浆[J].钻井液与完井液,2015,32(4):55-58.
[5]秦伟堂,张宏军,郑成胜,等.国内外油井水泥降失水剂概述[J].钻井液与完井液,2005,22(2):54-58.
[6]李早元,郭小阳,罗发强,等.油井水泥环降脆增韧作用机理研究[J].石油学报,2008,29(3):438-441.
[7]程荣超,步玉环,王瑞和.碳纤维增韧防窜油井水泥体系的试验研究[J].钻井液与完井液,2006,23(3):23-26.
[8]李波,邵鲁华,韩立国,等.固井用水泥外加剂研究进展[J].当代化工,2014,43(5):863-866.