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为解决泥浆污染、压裂液污染、水锁伤害、结垢堵塞等气井井底污染问题,川西气田每年都会进行20余井次的井底净化施工,但在对近5年井底净化施工井进行跟踪发现,不正确的选井施工不仅无法取得预期效果,而且浪费了作业费用。针对这个问题,利用模糊决策方法 ,以近3年的井底净化施工效果为基础,采用统计分析的方法,确定不同指标对决策结果的影响权重,并按照其相对比重进行评分:污染类型、井口压力、产量和剩余储量等四项正相关指标的最高分值为5分,一项负相关指标(根据施工成本、施工难度及是否污染储层确定综合评价排名)的最高分值定为-20分,进而形成井底净化选井模糊决策打分表。利用该表对2015年施工的井底净化井进行指导选井及背靠背评价,结果表明,该模糊决策打分系统与气井净化效果符合率达到100%,说明该方法能够有效指导施工选井。
In order to solve the problems of mud pollution, fracturing fluid contamination, water lock damage and scale fouling, etc., the well bottom purification work in more than 20 wells in the western Sichuan gas field is completed every year. However, Tracking found that incorrect selection of well construction not only failed to achieve the desired results, but also a waste of operating costs. Aiming at this problem, based on fuzzy decision-making method and based on nearly three years of bottom hole cleaning effect, statistical analysis is used to determine the influence weight of different indexes on the decision-making results, and the weight is calculated according to their relative proportions: pollution type, wellhead pressure , The highest score of four positive related indicators such as output and remaining reserves is 5 points. The highest score of a negative correlation indicator (based on construction cost, construction difficulty and whether to determine the ranking of comprehensive evaluation of contaminated reservoirs) is set as -20 , And then form a fuzzy decision scoring table of bottom hole cleaning selection well. The table is used to guide the well selection and back-to-back evaluation of the well bottom purification wells constructed in 2015. The results show that the coincidence rate of the fuzzy decision scoring system with the gas purification effect reaches 100%, which shows that the method can effectively guide the selection of wells.