Preparation And Evaluation Of Rare Earth Tracer And Its Application In Oilfield Development

Water injection development is the main production mode of oil fields at home and abroad.Due to the heterogeneity of reservoir plane and vertical,the difference of oil-water viscosity and other reasons,with the increase of water injection time,it is bound to cause the phenomenon of sudden and lingual injection of water.In order to solve the above problems,it is necessary to describe the reservoir precisely.Inter well tracer technology is an economic and effective fine description technology for heterogeneous reservoir.Through the dynamic data of tracer between oil wells,the corresponding relationship between oil and water wells,the distribution proportion of injected water and the advancing speed can be determined,and the flooded thickness,permeability,pore size and fault sealing can be determined Sex,etc.However,the chemical tracer used in domestic oilfields has large injection volume,high cost and low detection sensitivity,which can not meet the needs of field dynamic monitoring.After studying the development direction of the new tracer,the rare earth trace material tracer is selected as the research object to develop the tracer products suitable for the ultra-low porosity and ultra-low permeability reservoirs in Yanchang oilfield.In this paper,trace material tracers containing rare earth elements such as La,CE,y and Yb were prepared.The ratio of ligands and p H value in the preparation were tried and optimized,and the compatibility was verified by mixing with formation water.Finally,the molar ratio of rare earth elements to sodium sulfosalicylic acid is 1:3,and the p H value of the preparation is controlled between 5-6.Its performance is evaluated in laboratory.The results show that the loss rate of static adsorption test is less than 15 %,the loss rate of salt resistance test is less than 1 %,and the loss rate of interference test between tracers is less than 10 %.It is well compatible with the formation water in Yaodian and Danba areas,and the detection limit reaches ppb level.All the above performances are better than the industry standard SY/T 5925 Selection method of chemical tracer for oilfield water injection.Five water injection wells in Yaodian and Danba blocks were selected to determine the amount of tracer according to the Brigham Smith formula and the current situation of each test well to carry out the field test of rare earth trace material tracer.It is proved that the monitoring results are reliable.Through tracing and testing the tracer concentration in the water samples of produced wells and drawing the tracer production curve,the results of advancing speed of front water line and fitting interpretation of physical parameters are obtained,which provides scientific basis for the formulation,adjustment and implementation of oilfield water injection development plan.