Study On Mixed Multilayer Water And Scaling Formation In Yanchang Oilfield

Yanchang oilfield is located in a serious shortage of water resources in the north of Shaanxi province,which is the reservoir with low pressure,low permeability,multiple layer,and output water composition differences between the layers.In the process of oilfield development,the pipeline and equipment clogging in ground reinjection system and the formation pore blockage as a result of the phenomenon of serious scaling in the surface of the pipeline and gathering and transferring process,which is caused by the differences of different nature of the composition of produced water,and the thermodynamic instability of produced water,ultimately results in a drop in oil field production.This can seriously influence the oilfield development benefit.Therefore,the researches on compatibility and scaling formation of different layer of Yanchang oilfield produced water have very important significance,and then to provide a strong basis for oilfield anti-scaling measures.In this paper,the SY/T 5523-2006 standard was used in the field to analyze the characteristics of water quality in produced water system of Hengshan production plant and Xingzichuan production plant.And the static simulation method was used to analyze the scaling properties of different layers produced water mixed.We also discuss the different mixing ratio and mixing time on two series of mixed water scaling properties.Ion activity product method was applied to forecast trend of scaling.And then we can study their compatibility.The results show that:The produced water in Chang 2,Chang 6 of Hengshan Oil Production belongs to the high-salinity water.The two layers of water at the temperature of 30 Centigrade and stand for 72 hour will produce calcium sulfate scale.When the blending ratio of Chang 2 and Chang 6 is greater than 1:0.7,the fouling mass was above 300 mg/L and the calcium loss rate is more than 10%.When the mixed proportion of Chang 2 and Chang 6 ranges from 1:4 to 1:10,the calcium loss rate is less than 1%.With the loss of the long 2 proportion,the scale quantity is reduced.The mixed water of Chang 2 and Chang 6,and Chang 6 formation water were well distributed after dealing with the flocculation filtration and other processing,so you can return the mixed water to Chang 6 formation.The fouling mass of the mixture of output water in Chang 2,Chang 4+5 of Xingzichuan Oil Production is relatively low,and their compatibility is good.The mixed water after processing and then reinjection to Chang 2 and Chang 4+5 layer respectively is also stable.Apricots the Sichuan Oil Production director 2 6 mining the amount of water mixed scaling is relatively high,the most serious when the mixing ratio is 9:1 scale.The mixed water after treatment,mixed with Chang 2 and Chang 6,the mixing ratio of 1:9 to 2:8 range,good compatibility,can be reinjected into Chang 6;Apricots the Sichuan Oil Production director 6 and Chang 4+5 produced water mixed amount of scale is relatively low,the mixed water after treatment,and long4+5 good compatibility,you can re-injection layer 4+5;when mixing water with 6 mixed proportion in the range of from 1:9 to 3:7,preferably compatibility.