生物酶可降解钻井液降解效果评价方法

Evaluation Methods of Degradation Performance of Enzymatic Degradable Drilling Fluid System

生物酶可降解钻井液通过在钻进过程中对储层实现有效封堵、钻进完成后又可自动降解的原理,可对油气储层起到有效的保护作用。以实验数据为基础,以与实际生产的接近程度为标准,总结了生物酶可降解钻井液降解效果的6种评价方法,即黏度衰减法、泥饼清除法、渗透率恢复测定法、还原糖测定法、二氧化碳排放测定法、溶解氧测定法。结果表明,渗透率恢复测定法评价效果最有效,还原糖测定法、二氧化碳排量测定法测试过程太过繁琐、不适于现场实施,溶解氧测定法不适于评价生物酶对可降解钻井液的降解效果评价。

The biodegradable drilling fluid system can seal the reservoirs while drilling, and then it can be degraded automaticwhile drilling finished.As a result, the oil and gas reservoirs can be effectively protected.Based on the experimental data andactual production standard, six current degradation performance evaluation methods of enzymatic degradable drilling fluidsystem are summarized, which are viscosity attenuation method, mud cake clearance method, penetration rate of recoverymethod, reducing sugar testing method, carbon dioxide emissions method and dissolved oxygen method.The results showthat the method of permeability recovery rate is the most effective method, however, the method of reducing sugar assayand carbon dioxide emissions are not suitable for field applications, and the dissolved oxygen method is not suitable forevaluation of the biodegradable drilling fluid system which are degraded by enzyme.