环保型复合降滤失剂的研制与应用

为从源头上控制钻井液对环境的污染，减少废弃钻井液处理难度和处理费用，实现绿色环保钻井。以生物质材料植物多酚、木质素磺酸钠和玉米淀粉为原料，通过交联改性，合成了一种复合降滤失剂PLS。其EC₅₀为7.78×10⁴ mg/L,BOD₅/COD_Cr为5.05%，无毒且易生物降解。性能评价结果表明，含2%PLS的基浆在180℃下热滚16 h后中压滤失量仅为9.6 mL，且抗盐、抗钙性能优于羧甲基淀粉CMC-LV和两性离子淀粉接枝共聚物SAP。以PLS为唯一降滤失剂，配伍键合型润滑剂、双疏纳米封堵剂和仿生固壁剂等环保友好型处理剂，研制了一套环保型水基钻井液体系，并在大港油田某预探井的泥岩水平段进行了应用。应用井段内钻井液的流变与滤失性能稳定，摩阻低，泥饼薄而韧，无复杂情况发生，施工顺利。

Development and Application of an Environmentally Friendly Compound Filter Loss Reducer

To control the pollution of drilling fluids to the environment from the source and minimize the difficulty and cost of waste drilling fluid treatment, a compound filter loss reducer PLS has been developed through crosslinking modification of plant polyphenol (a biomass material), sodium lignosulfonate and corn starch. PLS is non-toxic and is easy to degrade, it has an EC₅₀ of 7.78 × 104 mg/L, and BOD₅/COD_Cr of 5.05%. Evaluation of PLS shows that a base mud treated with 2% PLS has API filtration rate of only 9.6 mL after hot rolling at 180 ℃ for 16 hours. PLS is better than carboxymethyl starch, CMC-LV and SAP (an amphoteric starch graft copolymer) in resisting salt and calcium contamination. An environmentally friendly water based drilling fluid was formulated with PLS as the only filter loss reducer and other environmentally friendly additives such as bonding lubricant, organo- and hydro-phobic nanometer plugging agent and bionic borehole wall strengthening agent. This drilling fluid was used to drill the horizontal mudstone section of an exploratory well in Dagang oilfield. The rheology, filtration property of the drilling fluid during drilling were very stable, the mud cake had low friction coefficient and was thin and tough. The drilling operation was successful with no downhole troubles encountered throughout the horizontal section.