Design and Performance Evaluation of Environmentally Friendly Water-Based Drilling Fluid System for Shale Gas Horizontal Wells
As energy demand continues to grow,the development and utilization of shale gas,as an important unconventional energy source,has received widespread attention.In this study,an efficient and environmentally friendly water-based drilling fluid system was designed and evaluated to address the technical problems in shale gas horizontal well drilling.Through indoor experiments,a drilling fluid system suitable for the area was selected as follows:3%bentonite slurry+3%ASAA+2%ASAB+2%temporary plugging agent+2%ASAC1+5%KCl.The designed drilling fluid system has an average apparent viscosity of 42 mPa∙s at a density of 1.2 g∙cm-3,a dynamic-to-plastic ratio of 0.39,and a water loss of 5.6 mL under high temperature and high pressure;at a density of 1.6 g∙cm-3,the apparent viscosity of the system is 73.1 mPa∙s,the dynamic-to-plastic ratio is 0.41,and the water loss under high temperature and high pressure is 5.5 mL.In addition,the system has good blocking performance and environmental friendliness,and its heavy metal content and biodegradability meet environmental requirements.The research results show that the environmentally friendly water-based drilling fluid system designed in this article can effectively meet the technical requirements of shale gas horizontal well drilling and has important practical application value and environmental protection significance.
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