大庆稠油热采汽窜封窜剂的研究

发布时间：2018-12-29 08:05

【摘要】：我国稠油资源丰饶,截至目前为止探明稠油地质储量16亿吨。热力采油(主要是蒸汽驱和蒸汽吞吐)是我国稠油藏开采的主要方法。大庆油田稠油热采时,由于储层非均质性、油气流度比差异等因素,导致汽窜现象经常出现,给大庆稠油的有效开发带来了困难。本文针对大庆油田稠油区块前期蒸汽驱、蒸汽吞吐中出现的汽窜问题,综合分析以往解决汽窜的化学封堵技术,根据稠油热采现场工艺特点,提出了以PVA改性脲醛树脂作为蒸汽驱封窜剂、以热致可逆凝胶作为蒸汽吞吐封窜剂的技术方案。首先,通过正交实验,得出脲醛树脂合成中各个因素对反应的影响程度,然后通过单因素实验,得到最佳合成工艺参数为:甲醛与尿素摩尔比为1:1.5;PVA加入量为0.5%;尿素分批加入的比例为70:25:5。并对合成的改性脲醛树脂进行了红外表征及可注入性分析。之后考察了PVA改性脲醛树脂质量分数、固化剂种类及浓度、延迟固化剂浓度对固化时间、固化强度的影响,最终确定了最佳的蒸汽驱封窜剂配方体系为:50%PVA改性脲醛树脂+500mg/L固化剂氯化铵+1000mg/L~10000mg/L延迟固化剂硫酸铵。其次,对以上配方体系进行了性能评价,评价内容包括:耐温、抗盐、抗老化、抗剪切、封堵性能等。评价结果表明:该配方体系在300℃下老化60d抗压强度仍能达到30Mpa;在3200r/min的转速下剪切1min后再次成胶,抗压强度仍能达到35Mpa;在10000mg/L矿化度的水中,其成胶状态仍为白色均匀固体;岩心封堵率在96%以上。再次,针对蒸汽吞吐的封窜剂进行了研究。从热致可逆凝胶的封堵机理、成胶机理出发,筛选出具有热可逆特性及良好成胶状况的MC20、MC450、HPMC50三种纤维素醚,研究了主剂用量对黏度、成胶温度及析水量的影响;蒸汽温度对凝胶析水量、成胶效果的影响;通过调节剂对凝胶析水量、成胶温度进行调节,最终确定了蒸汽吞吐封窜剂体系的配方为:主剂6.5%MC20+调节剂(1%~5%NaCl,1%~10%尿素,1%~10%NH4SCN)。最后,对上述蒸汽吞吐封窜剂配方体系进行了性能评价,评价内容包括:耐盐性能、热稳定性、封堵性能等。研究结果表明:在80℃下,随着矿化度的增加,相同质量分数的纤维素醚凝胶的粘度变化不大;热致可逆凝胶在200℃下的环境中恒温86h后,仍然能够成胶;岩心封堵率可达95%,封堵强度可达3.08MPa。根据室内研究结果可见,以上两种封窜剂对于汽窜的封堵效果,能够达到大庆稠油热采工艺要求,对于提高大庆稠油采收率具有非常重要的意义。
[Abstract]:Heavy oil resources in China are abundant, so far proved heavy oil geological reserves of 1.6 billion tons. Thermal recovery (mainly steam drive and steam huff and puff) is the main method of heavy oil production in China. During thermal recovery of heavy oil in Daqing Oilfield, due to the heterogeneity of reservoir and the difference of mobility ratio of oil and gas, the phenomenon of steam channeling often appears, which brings difficulties to the effective development of Daqing heavy oil. Aiming at the steam channeling problem in steam drive and steam huff and puff in the early stage of heavy oil block in Daqing Oilfield, this paper comprehensively analyzes the chemical plugging technology to solve steam channeling in the past, and according to the technical characteristics of thermal recovery of heavy oil, The technical scheme of using PVA modified urea-formaldehyde resin as steam drive channeling agent and thermally induced reversible gel as steam huff and puff sealing agent was put forward. First of all, through orthogonal experiment, the influence degree of each factor in the synthesis of UF resin was obtained. Then, through single factor experiment, the optimum synthetic parameters were obtained as follows: the molar ratio of formaldehyde to urea is 1: 1.5; The amount of PVA added is 0.5 and the proportion of urea in batches is 70: 25: 5. The modified UF resin was characterized by IR and its injectability was analyzed. The effects of mass fraction of PVA modified UF resin, type and concentration of curing agent and concentration of delayed curing agent on curing time and curing strength were investigated. Finally, the best formula of steam displacement channeling agent was determined as follows: 50%PVA modified urea-formaldehyde resin, 500mg/L curing agent, ammonium chloride, 1000mg/L~10000mg/L delayed curing agent, ammonium sulfate. Secondly, the properties of the above formulations were evaluated, including temperature resistance, salt resistance, aging resistance, shear resistance, plugging performance and so on. The results show that the compressive strength of the formula system can still reach 30Mpaafter aging at 300 鈩，

本文编号：2394556