Study On The Properties Of Startup Pressure Attenuation For Gelled Crude Oil

The objective of this paper which is based on the experiments which make use of The Model Loop-line Test Apparatus is to study the startup pressure under different pipe lengths and the startup pressure transmission and attenuation properties of Nan Yang crude oil with rate-controlled and pressure-controlled tests .The startup pressure transmitting speed with two kinds of startup methods and compressibility of the gelled crude oil are researched as well.The study finds that:1.For the rate-controlled restart tests of the open type pipeline, the startup pressure under different pipe lengths increases with the pipe lengths and the restart flow rate boosting and the startup temperature reducing.When the startup temperature is 40℃and the restart flow rate is 9.2mL/s, the startup pressure distribution along the loop appears linear approximately.2.For the rate-controlled pipeline restart tests,the pressure and time differences and the pressure gradient between the adjacent oil pressure sensors along the loop increase with the startup temperature decreasing ,and the increasing speed is faster.Also,the temperature point of oil rheology behavior variation exists,namely the pressure difference of each adjacent oil pressure sensor will increase markedly.3. Comparing the rate-controlled restart tests to the pressure-controlled restart tests,we can find that increasing pressure within a second of each adjacent oil pressure sensors along the loop appears increases with the restart flow rate and the startup pressure raising.However, the startup temperature produce different results.Because the pressure difference is the major factor in the rate-controlled restart tests and the time difference is the major factor in the pressure-controlled restart tests.4.In the process of rate-controlled and pressure-controlled restart tests,the pipe pressure reduces along the loop and appears linear approximately.The lower the startup temperature is, the larger the pressure attenuation will be and the faster the attenuation speed is.But the startup flow rate produce opposite effects.Besides,the higher the startup pressure is, the sharper the curve gradient of pressure drop along the pipe is,namely, the larger the pressure drop along the pipe will be.5.Under the low temperature state of rate-controlled pipeline restart tests,the pressure propagation speed reduces with the startup temperature falling and appears linear approximately.However, under the high temperature state of pressure-controlled pipeline restart tests,the pressure propagation speed reduces with the startup temperature raising.But the pressure propagation speed is independent of restart pressure and it has no changing at the same startup temperature.6. During the low and high temperature state of pipeline restart tests,the compressibility coeffcient and the compression wave speed are independent of temperature and they have no changing mostly.The pressure propagation speed in low temperature state is obviously smaller than the compression wave speed,but the pressure propagation speed in high temperature state is approximately equal to the compression wave speed.Therefore, the pressure propagation speed is much more useful in the practice.