温度和压力对深水钻井油基钻井液液柱压力的影响

根据不同温度和压力下油基钻井液密度的测量结果 ,建立了温度、压力影响下的油基钻井液密度计算模型。在模型中引入了热膨胀系数和弹性压缩系数 ,利用该模型计算了不同温度和压力下的钻井液密度值。模型计算的密度与实测值之间的最大相对误差小于 0 .3% ,平均相对误差为 0 .11%。利用该模型对深水钻井时不同条件下井眼内钻井液密度和液柱压力变化进行了计算和分析。结果表明 ,在深水钻井中 ,井眼内的钻井液密度通常大于井口钻井液密度 ;最大钻井液密度出现在海底泥线处 ;井眼内钻井液液柱压力的当量密度大于井口的钻井液密度。采用无隔水管钻井时的环空钻井液密度小于隔水管钻井时的钻井液密度。

Effect of temperature and pressure on fluid column pressure of wellbore drilling fluid in deep-water drilling with oil-based drilling fluid

A model for predicting densities of oil-based drilling fluid at different temperatures and pressures was developed on the analysis of measured data. The thermal expansion coefficient and elastic compression coefficient of oil-based drilling fluid were adopted in the model. The maximum error between the predicted results from the model and the measured data was less than 0.3 percent for each datum point, and the average error was less than 0.11 percent for all data points. This predicting model was used to analyze the variation of drilling fluid density and fluid column pressure in well bore at the different conditions during deep-water well drilling using oil-based drilling fluid. The analysis results show that the density of drilling fluid in the well bore is usually greater than the density of drilling fluid at the wellhead, and the maximum density of drilling fluid appears on the seafloor. The equivalent density of drilling fluid column pressure in well bore is usually greater than that at wellhead in riser drilling. The drilling fluid density in well bore annulus of drilled well without riser is less than that of riser drilling.