聚乙烯醇凝胶堵漏剂的室内研究

摘要

In this paper,a new PVA gel plugging agent was developed to deal with lost circulation.It is composed of polyvinyl alcohol (PVA),sodium borate,dibutyl and sodium carboxymethyl cellulose obtained through chemical crosslinking reaction.According to the performance requirements on plugging materials used for geological exploration drilling,this plugging agent was tested in terms of its gelling time,gelling viscosity,swelling,anti-dilution,mineral pollution resistance and plugging property.It is shown that the PVA gel plugging agent has the best performance when it is prepared with 3％ PVA,0.8％ sodium borate,0.3％ Dibutyl,0.3％ sodium salt of carboxymethyl cellulose(C-MC-Na) in the environment with crosslinking temperature at 35 ℃ and pH value at 10.Its gelling viscosity is 358 600 mPa · s and gelling time is 18 min.The gelling time is adjustable between 0.1 h and 1.0 h,well adapting to different channels.Besides,the maximum pressure resistance of an individual gel plugging agent is 6.0 MPa,and it increases to 7.0 MPa after 1％ wood dust is added,presenting a good plugging effect.It is concluded that this PVA gel plugging agent is advantageous with strong swelling,anti-dilution,mineral pollution resistance and plugging capacity.Moreover,its preparation is convenient with a low cost.Therefore,it can be used in fractures,caverns,pores and complex thief zones with movable water.%为解决地质钻孔钻井液漏失的问题,研制了一种新型堵漏剂——聚乙烯醇凝胶堵漏剂,该堵漏剂由聚乙烯醇、硼砂、二丁酯、羧甲基纤维素钠等化学交联反应而成.根据地质钻探钻孔堵漏材料性能的要求,对该堵漏剂进行了成胶时间、成胶黏度、溶胀性、抗稀释性、抗矿化物污染、堵漏等实验.结果表明:①当聚乙烯醇为3％、硼砂为0.8％、二丁酯为0.3％、羧甲基纤维素钠为0.3％、交联温度为35℃、pH值为10时,制备的聚乙烯醇凝胶堵漏剂性能为最好,成胶黏度达358 600 mPa·s,成胶时间为18min;②成胶时间在0.1～1.0h范围内可调,对不同大小通道适宜性好;③单独的凝胶堵漏剂最大承压能力达到6.0 MPa,加入1％木屑后最大承压能力提高到7.0 MPa,具有很好的堵漏效果.结论认为,所研制的聚乙烯醇凝胶堵漏剂具有较强的溶胀度、抗稀释、抗矿化物污染和堵漏能力,并且制备方便、价格低廉,可应用于裂缝、溶洞、孔隙及含有动水的复杂漏失地层.