考虑井筒温度场与压力场的深井井涌风险控制

深井、超深井井筒内温度场、压力场变化幅度较大。温度场及压力场的大幅度变化影响到了钻井液密度场,进而对井控安全产生影响。建立了井筒当量密度场分布模型,利用该模型计算了钻井液循环和静止时钻井液当量密度场分布情况,并探讨了井筒温度场压力场对井控过程的影响。研究表明:深井、超深井钻井井控过程中,应该考虑井筒温度场、压力场变化对钻井液物性参数的影响;钻井液循环和静止时,实际钻井液井底当量循环密度和当量静止密度低于将钻井液作为地面常数时的当量密度,井控时应该注意适当增大钻井液密度以平衡地层孔隙压力。采取相应的措施预防环空井底压力的减小带来的溢流、井涌甚至井喷。进行井身结构设计时,可以不考虑温度场与压力场的影响;另外井控事故预防控制需要技术及管理措施相结合。

Risk Control of Deep-well Well Blowout Considering Wellbore Temperature Field and Pressure Field

The range of wellbore temperature and pressure field is great for deep and ultra deep wells,it will have a significant impact on drilling fluid density field and then well control security.Develop a wellbore temperature field model,the drilling fluid density distribution is calculated when it is circulate and still,and then the influence of wellbore temperature and pressure field on well control process is discussed.Research shows:in the process of deep and ultra deep wells control,wellbore temperature and pressure field variation should be considered.When drilling fluid is circulating and still,the actual equivalent circulating density and equivalent static density is lower than as a ground constant,drilling fluid density should be enlarged to balance formation pore pressure,and some measures should be taken to prevent decrease of downhole annular pressure which may result in overflow,kicks and even blowout.When wellbore structure is designed,the influence of wellbore temperature and pressure field can be ignored.Prevention of well control accidents needs not only technologies but also management measures.