胶态FeS颗粒在电脱水器油水界面上的沉积与防治

Deposition of Colloidal FeS Particles on Oil-Water Interface in Electric Dehydrators and Its Control

大庆油田杏二联合站电脱水器内油水过渡层加厚 ,导致脱水电流过高 ,电场频繁破坏。为解决这一问题 ,研究了油水过渡层加厚的原因 ,研制了可防止这一现象出现的原油破乳剂。在电场破坏时脱出的污水呈黑色 ,含大量FeS颗粒 (134mg/L) ,SRB菌 (1.1× 10 5个 /mL)及其他细菌。FeS颗粒为胶态粒子 (粒径范围 <0 .0 4— 2 0 μm) ,为SRB产生的H2 S腐蚀油井和地面设备的产物。将黑色含油污水与含水原油配制成含水 70 %的乳状液 ,乳状液静置破乳时 (5 0℃ )脱出淡黄色污水 ,而油水过渡层破裂时脱出黑灰色污水 ,表明FeS颗粒沉积在油水界面。通过专门程序将FeS颗粒从污水分离 ,用含分离出的FeS颗粒的盐水和 45号变压器油配制含水 5 0 %的W/O乳状液 ,在乳状液分层时 (5 0℃ )出现了被胶态FeS颗粒稳定的油水中间层。筛选出了一种可使FeS颗粒表面转变为油湿从而进入油相的破乳剂 (DODD 3) ,以防止油水过渡层生成并增厚 ,用于人工配制的含FeS颗粒的含水 5 0 %的W /O型原油乳状液的破乳脱水时 (5 0℃ ,加量按总液量计为 5 0g/t) ,脱出污水水质 (吸光度 )和净化油含水两项指标均优于原用破乳剂。

The growth of an intermediate layer(IL) between oil and water phases in electric dehydrators at oil gathering/water treating plant Xing 2 of Daqing led to rather high electric current and frequent electric field destroy. To solve this problem, the causes of IL growth are investigated and a novel demulsifier is developed. The oily water separated while the electric field being destroyed is black in color and contains large amounts of FeS particles(934 mg/L) and SRB (1.1×10 5 cell/mL) and other bacteria. The FeS particles are of colloidal size (<0.04-20 μm) and are downhole and surface corrosion products by H 2S which is generated by SRB. In the course of breakdown at 50℃ of a water/crude emulsion prepared with the black oily water, yellowish water is separated and on rupture of the residual IL black liquor is relieved which indicates deposition of FeS particles on oil/water interfaces. Through a special procedure the FeS particlec are isolated from the oily water and dispersed again in a salt water. From this salt water and tranformer oil #45, an W/O emulsion (50/50) are prepared. When the emulsion is breaks down at 50℃ an IL stabilized by FeS particles appears. To prevent IL growth, a demulsifier, DODD 3, is developed to make the FeS particles oil wetting and transfered into the oil phase. In the use of DODD 3 for demulsifying/dehydrating W/O emulsion with FeS added at 50℃ the separated water quality (light transmmision) is better and the oil content in the purified crude oil is lower than that by the demulsifier used then.