中国页岩气水基钻井液技术研究应用进展及发展展望OA

In the context of high-speed development of shale gas industry in China,the shortages of oil-based drilling fluid in environmental protection and cost get increasingly prominent.Driven by the demand for green and efficient development of shale gas in China,it is in urgent need to develop high-performance water-based drilling fluid which is comparable to oil-based drilling fluid in comprehensive performance,so as to achieve the strategic goal of"water replacing oil".To this end,this paper systematically reviews the history of shale gas development in China,analyzes the key technical bottlenecks of water-based drilling fluid,and summarizes the research progress of core treating agent and system construction as well as the application performance of domestic typical systems.Based on this,the development direction of novel high-performance water-based drilling fluid system is pointed out.The following results are obtained.First,China's researches on the water-based drilling fluid technologies for shale gas focus on three core aspects,i.e.,borehole stability,friction and drag reduction,and wellbore cleaning.The high-performance water-based drilling fluid system suitable for the target block is developed by optimizing treating agent while giving consideration to compatibility and synergism.Second,the drilling fluid systems for the main shale gas producing areas in China are all prepared focusing three core functions of strong inhibition,strong plugging and high lubrication,which achieves the effective replacement of oil-based drilling fluid preliminarily,promoting the water-based drilling fluid systems for shale gas to be refined,diverse,and environmentally friendly.Third,existing systems face great difficulty in ensuring long-term borehole stability,the drag torque in long horizontal sections is still high,and some systems suffer deteriorating rheological property.And these problems restrict the drilling process of extra-long horizontal wells.In conclusion,China's water-based drilling fluid for shale gas has already possessed the foundation for large-scale replacement.And in the future,it is necessary to research the technologies applicable to ultra-long horizontal wells with simple formula,environmental friendliness,and low cost by interpolating nano materials and intelligent control technologies,so as to realize the transformation from"empirical trial and error"to"mechanism driven".