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磨溪气田嘉二段气藏具有典型的“高压、高渗、高含硫”特点,以往所钻的直井及水平井在φ152.4mm小井眼井段使用聚磺钻井液密度一般为2.30~2.50g/cm3,几乎每口井都出现多次滤饼粘附卡钻;另外该井段富含石膏及夹薄层岩盐对钻井液污染严重,流变性不好控制,钻井中常出现高泵压等问题。针对以上难题,从分析高密度条件下的粘卡原因及出现高泵压的流变性失控原因入手,研制了一种超高密度低油水比水包油钻井液体系,室内进行了产层岩样密封能力、滤饼表面油润湿性、抗膏盐污染等方面的评价,现场应用于磨005-H8井水平段钻井中取得了良好效果。表明该配方体系能较好地满足磨溪气田所钻井的需要,大幅度地降低了钻井扭矩和起下钻摩阻,能有效防止粘附卡钻和高泵压问题,具有高密度条件下流变性易控制、抗膏盐污染能力强、对泵橡胶件损害小、安全经济等优点。
The gas reservoir of Jia2 section in Moxi gas field has the characteristic of “high pressure, high permeability and high sulfur content”. The density of the polysulfide drilling fluid used in the φ152.4mm slim well section of vertical and horizontal wells drilled in the past is generally 2.30 ~ 2.50g / cm3, there are many filter cake sticking stuck in almost every well. In addition, gypsum and thin layers of rock salt are rich in gypsum and thin layers of rock salt, which cause serious pollution to drilling fluid and poor rheology control. Pressure and other issues. In view of the above problems, starting from the analysis of the causes of sticking in high density conditions and the reasons of losing control of the high pumping pressure, an ultra-high density, low oil-water ratio oil-in-water drilling fluid system was developed. Sealing ability, surface wettability of filter cake and anti-gypsum salt contamination. The field application in the horizontal well of the well 005-H8 has achieved good results. The results show that the system can meet the need of well drilling in Moxi gas field, greatly reduce the drilling torque and drag-down resistance, effectively prevent sticking stuck and high pump pressure, and have high density rheological properties Easy to control, anti-gypsum pollution ability, damage to pump rubber parts, safety and economy.