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流变测试系统内,经剪切处理后的胶凝原油存在明显的各向异性,其各向异性将导致现有的管道非稳态流动数值模型不再适用。为了对比在不同剪切条件下胶凝原油剪切力学特性与轴向力学特性的差异,分析其各向异性,以胜利原油和南阳原油为例,控制不同剪切速率、剪切时间等因素对原油进行预剪切处理,分别开展剪切应力松弛实验和轴向压缩松弛实验。对实验数据进行拟合,对比相同条件下胶凝原油的剪切松弛模量和轴向压缩松弛模量,结果表明:相同条件下,胶凝原油的压缩松弛模量远远大于其剪切松弛模量,且随剪切速率的增大、剪切时间的增加,其剪切松弛模量和压缩松弛模量相差越来越大,即各向异性更加显著。研究结果为胶凝原油管道的停输再启动提供了理论依据与技术支持。
In the rheological test system, there is obvious anisotropy of shear-treated gelatinized crude oil. The anisotropy of the gelation crude oil will not be applicable to the existing numerical model of unsteady flow in pipelines. In order to compare the shear mechanical properties and axial mechanical properties of gelatinized crude oil under different shear conditions, the anisotropy was analyzed. Taking Shengli Crude Oil and Nanyang Crude Oil as examples, the factors such as shear rate and shear time were controlled The crude oil was subjected to pre-shear treatment, and the shear stress relaxation experiment and the axial compression relaxation experiment were carried out respectively. The experimental data were fitted to compare the shear relaxation modulus and the axial compression relaxation modulus of gelatinized crude oil under the same conditions. The results show that under the same conditions, the compressive relaxation modulus of gelling crude oil is far greater than its shear relaxation Modulus, and with the increase of shear rate, shear time increases, the shear relaxation modulus and compressive relaxation modulus difference is more and more large, that is more pronounced anisotropy. The results provide a theoretical basis and technical support for the shutdown of cementitious crude oil pipeline.