钻井液用双保加重剂的研制与应用

Development and Application of Double-protection Weighting Agent for Drilling Fluid

针对重晶石、铁矿粉、钛铁矿粉和碳酸钙类加重剂环保性能及应用性能的不足,通过优选碳酸钙类加重剂方解石,并按重晶石、方解石的质量比为7∶3复配得到双保加重剂,通过粒度匹配、干法活化处理和表面涂覆改性等生产工艺对双保加重剂的性能进行了优化,研究了双保加重剂与4种钻井液的配伍性及对油气层的保护效果,并在大港油田10口井进行了现场应用,评价了其对环境的影响。结果表明,双保加重剂降低了对钻井液黏度的影响,与钻井液的配伍性较好,解决了砷超标问题,对油气层的保护效果良好,岩心渗透率恢复值较重晶石加重可提高15.2百分点。现场应用结果表明,实施井均安全钻进,与邻井均值相比,机械钻速提高49.18%,平均井径扩大率降低1.84百分点,投产井平均单井每米产层增油0.60 t,滤饼重金属砷含量低于60 mg/kg,达到国家标准要求。

In view of the deficiency of environmental protection and application performance of weighting agent including barite,iron ore powder,ilmenite powder and calcium carbonate,the double-protection weighting agent was obtained by optimizing calcium carbonate weighting agent calcite,and compounded barite and calcite in mass ratio 7∶3.The performance of doubleprotection weighting agent was optimized by particle size matching,dry activation treatment and surface coating modification.The compatibility of double-protection weighting agent with four kinds of drilling fluids and its protective effect on oil and gas reservoir were studied.It was applied on 10 wells in Dagang oilfield to evaluate its impact on the environment.The results showed that the double-protection weighting agent reduced the influence on the viscosity of drilling fluid,had good compatibility with drilling fluid,solved the problem of arsenic exceeding the standard requirements and had a good protection effect on oil and gas reservoir.The core permeability recovery value could be increased by 15.2 percentage points compared with that of barite.Field application results showed that the drilling of implementation wells was carried out safely.Compared with the average value of adjacent wells,the rate of penetration was increased by 49.18%,the average diameter expansion rate was reduced by 1.84 percentage points,and the single well in average had an oil increase of 0.60 t per meter in production zone.The heavy metal arsenic content of filter cake was less than 60 mg/kg,which met the requirements of national standard.