钻井液用石蜡乳油的制备及应用

针对钻井液用O/W型石蜡乳液易破乳分层、析蜡结块的乳液稳定性难题，采用复配乳化剂将液体石蜡、植物油、白油组成的油脂相在一定条件下制备成有效成分含量达100%的石蜡乳油。为进一步提高石蜡乳油的润滑性，采用捏合干燥工艺对纳米二氧化硅微球表面进行预处理，并借助二氧化硅专用分散剂和稳定剂球磨分散到乳油体系中，经稳定性研究试验发现充分悬浮分散的纳米二氧化硅微球具有良好的热稳定性和机械稳定性。石蜡乳油相比于传统石蜡乳液具有更高的存储稳定性和使用便利性，可与水任意比例混溶形成O/W型石蜡乳液。性能试验表明：1%石蜡乳油加入淡水聚磺钻井液体系，API滤失量降低33.8%，润滑系数降低率28.6%，加入5%盐水聚磺钻井液体系，API滤失量降低26.7%，润滑系数降低率23.4%，石蜡乳油与聚磺钻井液体系配伍性良好，可完全替代传统石蜡乳液。该石蜡乳油在松辽盆地北8井进行了现场入井试验，试验井段井壁稳定、钻井液润滑性能提升明显，试验效果良好。

Preparation and application of paraffm emulsifiable concentratefor drilling fluids

To solve the emulsion stability problem of paraffin emulsion in drilling fluid, which is easy to demulsification and agglomeration, a paraffin emulsifiable concentrate (EC) with an effective component of 100% was prepared by using compound emulsifiers under certain conditions. In order to improve the lubricity of paraffin EC, nano silica microspheres were preprocessed by kneading drying process and dispersed to the EC system with special dispersant and stabilizer. The stability test showed that the fully suspended nano silica microspheres had good thermal stability and mechanical stability. Compared with the traditional paraffin emulsion, paraffin EC has higher storage stability and ease of use. It can be mixed with water at any ratio to form O/W paraffin emulsion. Performance tests showed that: when 1% paraffin EC was added to the fresh polysulfonate drilling fluid system. the API filtrate loss decreased by 33.8% and the lubricating coefficient decreased by 28.6%. Added 5% salt water polysulfonate drilling fluid system, the API filtrate loss decreased by 26.7%, and the lubricating coefficient reduction rate was 23.4%. Paraffin EC has good compatibility with polysulfonate drilling fluid system and can completely replace traditional paraffin emulsion. Paraffin EC has been tested in the well Bei8 of Songliao Basin. The results showed that the wellbore of Bei8 was stable, the lubricity of drilling fluid was improved obviously, achieved the experimental goals.