高温高压井ECD计算

随着深部油气藏的勘探和开发，高温高压深井及超深井的数量大幅度增加，而高温高压、窄安全密度窗口安全钻井是当前国内外未能很好解决的重大技术难题，钻井工艺技术面临易发生井漏、井喷等事故的挑战，准确计算钻井过程中井下ECD分布对突破该技术难关有重要意义。为此，文章从研究高温高压钻井过程中循环温度场分布出发，分析了温度和压力对钻井液密度的影响规律，建立了不同温度和压力条件下的ECD实时耦合模型。该模型由动态压力和温度模型耦合而成。通过计算分析表明，井底钻井液密度和地表钻井液密度有很大差别；温度增加，钻井液密度下降；压力增加，钻井液密度增加。在高温高压钻井过程中，随着循环时间的增加，环空下部井段温度呈指数降低，ECD升高；环空上部井段温度呈指数升高，ECD降低。随着排量增加，环空下部井段温度降低，ECD近似呈线性升高；环空上部井段温度升高，ECD呈指数降低。

ECD COMPUTATION FOR HPHT WELLS

Starting from the study on the temperature field in the annular space, it is discussed about the rule by which the temperature and pressure affect the density. Thus, it is developed the real-time ECD models for different temperatures and pressures. The research indicates that when the circulating time increases, the temperatures at the lower annular space will decrease exponentially and the ECD will increase; the temperature in the upper annular space will increase exponentially and the ECD will decrease. And with the higher flow rate, the temperature at the lower annular space will decrease and the ECD will increase linearly; the temperature at the upper annular will increase and the ECD will decrease exponentially.