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巴西有90%以上的石油和天然气储量位于海域,并且总储量的60%以上位于深海和超深海域。在深海和超深海域钻井存在一些技术问题,主要为地层破裂压力梯度低、节流管线长、泥浆管线温度低。更好地了解合成基钻井液中天然气的溶解度,有利于井控。现在的工作包括两种有机液体(正链烷烃和酯)的PVT(压力体积温度)特性研究,这两种有机液体目前正在Campos盆地(巴西里约热内卢)的深海和超深海钻井中应用。在158和194温度下测定了甲烷液体混合物的热力学特性,如饱和压力、溶解度、原油的地层体积系数、天然气的地层体积系数和液体的密度。测量由两种不同仪器完成:一种为含汞系统,另一种为无汞PVT系统。结果显示,正确地认识地层天然气在井下条件和井涌循环期间的溶解度对于在深海和超深海安全钻井非常重要。
Over 90% of Brazil’s oil and gas reserves are located in the sea, and more than 60% of the total reserves are located in deep and ultra-deep waters. There are some technical problems in deep-sea and ultra-deep sea drilling, mainly because of low formation pressure gradient, long throttle line and low slurry pipeline temperature. Better understanding of the solubility of natural gas in synthetic base fluids is good for well control. Current work includes studies on PVT (Pressure Volume Temperature) properties of two organic liquids (n-paraffins and esters), which are currently being used in deep and ultra-deep sea drilling in the Campos Basin (Rio de Janeiro, Brazil). Thermodynamic properties of the methane liquid mixture, such as saturation pressure, solubility, formation volume factor of crude oil, formation volume factor of natural gas, and liquid density, were measured at 158 and 194 temperatures. The measurements were made by two different instruments: one for the mercury-containing system and the other for the mercury-free PVT system. The results show that correctly understanding the solubility of formation gas during downhole conditions and kick cycles is important for safe drilling in deep and ultra-deep sea.