保护油气层的防塌钻井液技术研究

保持井眼稳定和保护油气层不受损害涉及较多的工程环节,存在诸多影响因素,钻井液则是系统工程中的一个重要环节.钻井液是打开油气层的第一种工作液,其性能好坏不仅影响钻井施工的正常进行,而且直接影响油气层保护和油气产量.钻井液密度是钻井液的重要性能指标,直接关系到钻井压差的高低.如果按照钻井压差的大小则可把钻井液技术分为两大类,即正压差钻井液技术和负压差钻井液技术.从油气层保护的角度,分析了钻井液密度与井眼稳定和油气层保护的辩证关系,以及钻井液对油气层的损害机理和相应的保护措施,提出了多元协同防塌新原理,即在处理井眼不稳定现象时,除了要考虑钻井液的因素外,还要综合考虑地质、工程、水力学等方面的因素.重点介绍了目前国内外防塌与保护油气层的稀硅酸盐钻井液、有机盐钻井液、聚合醇(又称多元醇)钻井液和合成基钻井液等代表性钻井液新技术.

Study on anti-sloughing drilling fluid technology for oil and gas reservoir protection

To maintain a stable hole and to keep the reservoir from damaged, several engineering factors are involved, of which the drilling fluid is an important one. Drilling fluid is the first working fluid that opens oil and gas reservoir, and its properties affect both drilling performance and formation damage control. The density of drilling fluid is an important property index which has direct influence on drilling pressure differential. According to the drilling pressure differential, drilling fluids can be classified into two types: positive and negative pressure different drilling fluids. In this paper, from the point of formation damage control, the relationships between driling fluid density and well bore stability, and drilling fluid density and oil/gas reservoir protection were firstly analyzed respectively;secondly the mechanism of the damage of drilling fluid to oil and gas reservoir was analyzed and the methods for formation damage control and anti-sloughing were proposed, that was, when a problem of well bore stability was dealt with, not only the drilling fluid, but also other factors of the well such as geology, engineering and hydraulics etc.should be taken into consideration. Finally the new anti-sloughing drilling fluid technologies for reservoir protection at home and abroad including dilute silicate drilling fluid, polycol drilling fluid and synthetic base drilling fluid were introduced.