Study on the regularity of scale formation and chemical control measures of oil field waterflood
The multi-layer system in Block X of Ordos Basin was developed at the same time,and the produced water in different layers was not separated and mixed for reinjection operation,resulting in the injection pressure rising.In this paper,the scale formation rules of the produced water and its mixed water developed at S,M and Z layers in Block X were analyzed through static simulation experiments,and the compatibility of produced water at each layer was analyzed by testing light transmission and core damage rate.Finally,the evaluation and optimization experiments of five types of chemical scale removal agents were carried out.The results show that the produced water in the S and Z layers of Block X is CaCl2 water type,and the produced water in the M layer is Na2SO4 water type.The scale formation amount of the same water type is very small at 40～90℃,and the compatibility is good.After mixing the produced water of S-layer/M-layer and M-layer/Z-layer,the scale amount is large and the compatibility is poor,and the maximum scale amount and the maximum damage rate to the core appear under the mass ratio of 1∶1 and 3∶1 respectively.Compared with phosphate,phosphate ester and carboxylic acid,the organic compound phosphonic acid anti-scale agent showed the best anti-scale effect and the lowest dosage.The critical concentration of anti-scale agent was 10～15mg·L-1,and the anti-scale rate reached 95.8%.
mixed produced waterformation scalingoptimization of anti-scale agentscaling rulechemical prevention
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