七里村采油厂油井结蜡机理

Waxing Mechanism of Oil Wells in Qilicun Oil Production Plant

对七里村采油厂易结蜡区块典型原油基本物性、析蜡点、石蜡胶质沥青质含量进行了分析,考察了原油含水量、轻组分含量、流速、温度和管线表面状态等对原油结蜡的影响。结果表明:原油凝点低,粘度低,密度低,石蜡胶质沥青质含量高,析蜡点高;原油结蜡速率随原油含水量、轻组分含量增加而减小,随着原油温度升高先增大后减小,随着结蜡室温度升高而降低,管线表面越光滑结蜡速率越小。其结蜡机理为:原油中蜡、胶质含量高轻组分含量低,地层压力低,地层温度与原油析蜡点相近,在开采过程中,原油中伴生气溢出使轻组分减少,降低了原油对蜡的溶解能力,因此导致原油结蜡。试验区域油井普遍产量低,采取间断方式采油,原油在油管中流速低、滞留时间长,有利于析出蜡晶在油管表面附着、聚集长大并吸附在油管内壁和油杆外壁,从而造成油井结蜡现象发生。

The basic properties,such as condensate point,viscosity,density,wax-producing point,the content of heavy constituents(resin,asphaltene,and wax)of typical crude oil in the waxy block of Qilicun oil production plant were analyzed.And the influence of the water content,the light constituents content,the flow rate,the temperature of crude oil and the surface state of pipelines on the wax were studied.The results show that the condensate point,the viscosity and the density are low,and the content of heavy constituents is high.The wax rate of crude oil decreased as the content of water and light constituents increased.When the temperature of crude oil increased,the wax rate increased first and then decreased;the wax rate decreased as the temperature of wax chamber(outside the waxy tube)rose,and the smoother of the pipeline surface,the slower the rate of wax deposition.The wax precipitation is as follows:the content of resin and wax in crude oil is higher,while the condensate point,the content of light constituents and the reservoir pressure is lower.The reservoir temperature is close to the wax precipitation point of crude oil;the overflow of associated gas in crude oil,the content of light constituents decreased during the production process,and the ability of wax to be dissolved decreased,resulting in wax deposition of crude oil.The production of oil wells in the test area is universally low.The crude oil produced by intermittent method has low flow rate and long residence time in tubing.The wax precipitated easily adhered to the surface of the oil well,accumulates and adsor.