微观蜡晶特征在流变曲线上的宏观体现
|
摘要
为了研究证明含蜡原油流变曲线和微观蜡晶两者之间存在一定的关联,测试了广范围剪切速率下的含蜡原油流变曲线,确立了微观蜡晶和流变曲线之间的定性关系,并且取得以下认识:广范围剪切速率下的含蜡原油流变曲线能够一定程度地体现微观蜡晶特征,其中低剪切速率下的流变曲线能够体现蜡晶形态,高剪切速率下的流变曲线能够体现蜡晶结构;并非温度越低,剪切速率对粘度的影响程度越大,在高剪切速率下,有可能存在相反的情况;在低温条件下,剪切速率存在一个临界值,只有当剪切速率大于该值时,粘度才会出现较为明显的下降;温度越低,形成的蜡晶网格结构越稳定,需要较大的剪切应力,蜡晶网格结构才能破坏。该研究成果深化了对含蜡原油流变性的认识,具有一定的理论意义。
In order to research to prove that there is a correlation between the rheological curve of waxy crude and the microscopic wax crystal, the rheological curve of waxy crude under wide range of shear rate is tested to build the qualitative relationship between microscopic wax crystal and rheological curve. The result shows that the rheological curve of waxy crude under wide range of shear rate can refl ect the microscopic wax crystal characteristics to some degree and the rheological curve under low shear rate can refl ect the form of wax crystal, while the rheological curve under high shear rate can refl ect the wax crystal structure. Besides, it is not always the case that the lower the temperature is, the bigger the infl uence of shear rate on viscosity is. Under high shear rate, the situation could be the opposite. At low temperatures, shear rate has a critical value and only when the shear rate is higher than the critical value can there be a relatively obvious fall in viscosity. The lower the temperature is, the more stable the formed wax crystal grid structure is, which requires high enough shear stress to break down. This research result deepens the understanding of rheological property of waxy crude and is of some theoretical signifi cance.
In order to research to prove that there is a correlation between the rheological curve of waxy crude and the microscopic wax crystal, the rheological curve of waxy crude under wide range of shear rate is tested to build the qualitative relationship between microscopic wax crystal and rheological curve. The result shows that the rheological curve of waxy crude under wide range of shear rate can refl ect the microscopic wax crystal characteristics to some degree and the rheological curve under low shear rate can refl ect the form of wax crystal, while the rheological curve under high shear rate can refl ect the wax crystal structure. Besides, it is not always the case that the lower the temperature is, the bigger the infl uence of shear rate on viscosity is. Under high shear rate, the situation could be the opposite. At low temperatures, shear rate has a critical value and only when the shear rate is higher than the critical value can there be a relatively obvious fall in viscosity. The lower the temperature is, the more stable the formed wax crystal grid structure is, which requires high enough shear stress to break down. This research result deepens the understanding of rheological property of waxy crude and is of some theoretical signifi cance.
引文
[1]李鸿英,张劲军.蜡对原油流变性的影响[J].油气储运,2002,21(11):6-12.
[2]冯兵,何光渝,蒋华义,等.剪切历史对长庆含蜡原油流变性的影响研究[J].润滑与密封,2009,34(4):67-70.
[3]李鸿英,丁建林,张劲军.含蜡原油流动特性与热历史和剪切历史的关系[J].油气储运,2008,27(5):16-20.
[4]IJEOMAH Cajetan E,DANDEKAR Abhijit Y,CHUKWU Godwin A,et al.Measurement of wax appearance temperature under simulated pipline(dynamic)conditions[J].Energy&Fuels,2008,22(4):2437-2442.
[5]LI H,GONG J.The pressure effect on rheological behavior of water content of waxy crude oil[J].Petroleum Science and Technology,2011,29(13):1344-1352.
[6]关中原.我国油气储运相关技术研究新进展[J].油气储运,2012,31(1):1-7.
[7]姜笃志.管道流体流变性的一般规律研究[J].油气储运,2009,28(4):9-14.
[8]柳建军,程华,崔秀国,等.应用非线性隐式迭代法回归含蜡原油触变模型[J].油气储运,2011,30(1):12-14.
[9]李其抚,苗青,胡森,等.控应变流变仪测试含蜡原油的胶凝过程[J].油气储运,2010,29(12):891-892.
[10]孙长征,宇波,孙昌赞,等.含蜡原油管道停输再启动数值模拟触变流体的简化方法[J].油气储运,2010,29(6):417-418.
[11]LETOFFE J M,CLAUDY P,KOK M V,et al.Crude oils:characterization of waxes precipitated on cooling by DSC and thermomicroscopy[J].Fuel,1995,74(6):810-817.
[12]ANDERSON Tor,PETERS H Scott,TORRES Rosario A,et al.Wax crystal size distribution versus composition[J].Fuel,2001,80(11):1635-1638.
[13]FERWORN Kevin A,HAMMAMI Ahmed,ELLIS Herb.Control of wax deposition:An experimental investigation of crystal morphology and an evaluation of various chemical solvents[C].International Symposium on Oilfield Chemistry,Houston,Texas,USA,February 18-24,1997.
[14]KANE Moussa,DJABOUROV Madeleine,VOLLE Jean luc,et al.Morphology of paraffin crystals in waxy crude oils cooled in quiescent conditions and under flow[J].Fuel,2003,82(2):127-135.
[15]黄启玉,张劲军,严大凡.高速剪切后加剂原油低温流动性的恢复[J].油气储运,1999,18(10):6-8.
[2]冯兵,何光渝,蒋华义,等.剪切历史对长庆含蜡原油流变性的影响研究[J].润滑与密封,2009,34(4):67-70.
[3]李鸿英,丁建林,张劲军.含蜡原油流动特性与热历史和剪切历史的关系[J].油气储运,2008,27(5):16-20.
[4]IJEOMAH Cajetan E,DANDEKAR Abhijit Y,CHUKWU Godwin A,et al.Measurement of wax appearance temperature under simulated pipline(dynamic)conditions[J].Energy&Fuels,2008,22(4):2437-2442.
[5]LI H,GONG J.The pressure effect on rheological behavior of water content of waxy crude oil[J].Petroleum Science and Technology,2011,29(13):1344-1352.
[6]关中原.我国油气储运相关技术研究新进展[J].油气储运,2012,31(1):1-7.
[7]姜笃志.管道流体流变性的一般规律研究[J].油气储运,2009,28(4):9-14.
[8]柳建军,程华,崔秀国,等.应用非线性隐式迭代法回归含蜡原油触变模型[J].油气储运,2011,30(1):12-14.
[9]李其抚,苗青,胡森,等.控应变流变仪测试含蜡原油的胶凝过程[J].油气储运,2010,29(12):891-892.
[10]孙长征,宇波,孙昌赞,等.含蜡原油管道停输再启动数值模拟触变流体的简化方法[J].油气储运,2010,29(6):417-418.
[11]LETOFFE J M,CLAUDY P,KOK M V,et al.Crude oils:characterization of waxes precipitated on cooling by DSC and thermomicroscopy[J].Fuel,1995,74(6):810-817.
[12]ANDERSON Tor,PETERS H Scott,TORRES Rosario A,et al.Wax crystal size distribution versus composition[J].Fuel,2001,80(11):1635-1638.
[13]FERWORN Kevin A,HAMMAMI Ahmed,ELLIS Herb.Control of wax deposition:An experimental investigation of crystal morphology and an evaluation of various chemical solvents[C].International Symposium on Oilfield Chemistry,Houston,Texas,USA,February 18-24,1997.
[14]KANE Moussa,DJABOUROV Madeleine,VOLLE Jean luc,et al.Morphology of paraffin crystals in waxy crude oils cooled in quiescent conditions and under flow[J].Fuel,2003,82(2):127-135.
[15]黄启玉,张劲军,严大凡.高速剪切后加剂原油低温流动性的恢复[J].油气储运,1999,18(10):6-8.