Compression characteristics of gelled crude oil

In this paper, the Daqing crude oil was studied in terms of compression characteristics by using the independently developed crude-oil compression experiment device. It is shown that the gelled crude oil is characterized by complex compression before its yield failure of wax crystal network structure, but is in line with the elastic compression characteristics after its yield failure of wax crystal network structure. And the compression can be calculated by means of the formulas presented in available literatures. Then, based on the independently developed conduit-flow loop experiment device, analysis was conducted on the elastic-plastic compression characteristics of Sudan gelled crude oil before its yield failure of wax crystal network structure. It is presented that the pressure in loop drops continuously with the recovery of wax crystal network structure in gelled crude oil during the constant-temperature static process after shutdown. It is indicated that the pressure drop in the loop is caused by volume contraction of the wax crystal network structure. The lower the oil temperature is, the greater the pressure drops and the more the volume shrinks. Based on the research results of Sudan crude oil constant-temperature startup, the elastic-plastic compression characteristics of gelled crude oil during the loop initial startup was studied by using an inversion simulation calculation method. Its elastic-plastic compressibility coefficient is much higher than the elastic compressibility coefficient at the same temperature. The lower the oil temperature is, the higher the wax crystal network structure strength is and the greater the elastic-plastic compressibility coefficient is.