Abstract: The components of the representative oil sample acquired from Unity 21 Well in Sudan were analyzed.The cloud point of wax was tested, and the wax deposition rate was measured with the automatic high-pressure wax deposition flow loop developed by the Research Institute of Petroleum Exploration and Development in cooperation with TEXACO of U.S.A.In order to simulate the production conditions, the cooling procedure was used to study the effects of the flow rate, oil temperature and ambient temperature on the wax deposition. The temperature in the cooling procedure ranges from that higher than the cloud point to lower one. The increase of flow rate resulted in a lower wax deposition rate. The experimental data were scaled up for waxy crude production line with a semi-empirecal scale-up wax deposition model. The wax deposition mechanism was described with the molecular diffusion and shear effects. The critical wax tension was used as a scalar. The wax deposition profiles along the production lines in the Unity 21 Well were predicted. The modeling results show that some factors have some impacts on the wax deposition profiles such as oil production rate and production time. No wax deposit in production line when the production rate is high enough. When the oil production rate is low, wax might deposit in the production line, and some wax-control techniques should be applied.

Key words: wax deposition, critical wax tension, simulation, production status, well bore, wax deposition mechanism, waxy crude

摘要： 对从苏丹Unity油田现场取得有代表性的原油样品进行了原油组分分析和析蜡点测试。并针对油田的生产状况,利用与美国德士古石油公司合作建立的自动化高压石蜡沉积循环管道模拟系统,采用冷却实验步骤测试了苏丹原油从高于原油析蜡点温度到较低环境温度范围内在现场流速、油温和环境温度下的石蜡沉积速率,定量研究了流速和油温对石蜡沉积速率的影响,并采用分子扩散和剪切效应的总效应来描述石蜡沉积机理。利用临界蜡张力作为模拟放大因子,采用半经验的石蜡沉积数学模型,预测了Unity油田21井的生产井筒在现场生产条件下的石蜡沉积情况,模拟了不同产量和不同时间的蜡沉积剖面。结果表明,该油井在目前高产条件下,未发生石蜡沉积问题;在低产时,须考虑清蜡和防蜡措施。

关键词: 石蜡沉积, 临界蜡张力, 模拟研究, 生产工况, 井筒, 石蜡沉积机理, 含蜡原油