Evaluation And Safety Of Oxidation Breaker Potassium Persulfate

Oil and gas occupy the large proportion of national energy sources,and oilfield exploitation attaches great importance to the development of the drilling technology.Gel breaker can effectively remove the filter cake,solid particles during the mining process,and dredge the production capacity of the oil wells.At present,oxidative breaker is the widely used,which can quickly achieve the gel breaking.However,oxidation breaker has strong oxidizing,which will exist security risk.In order to ensure the safety and stability of oxidation breaker in loading,combining the theory with the actual situation,potassium persulfate(K2S20g)was selected as the main raw material and blended with another four kinds of stabilizer.The thermal stability of K2S2O8 and mixed components was characterized by differential scanning calorimetry analyzer(DSC)and thermal gravimetric analyzer(TGA).The results showed that activation energy of K2S2O8 is 170.6 kJ·mol-1,adding carbon black will induce the decomposition of K2S2O8.The activation energy of mixed components is132.88 kJ·mol-1.covalent bonds of K2S2O8.will fracture and release peroxide,the oxygen combines with the carbon bond or functional groups,and hinder the further oxidation and decomposed of K2S2O8,the activation energy is 399.1 kJ·mol-1 at this time.Therefore,carbon black can improve the thermal stability of K2S2O8 significantly and the optimal content was above 2.5%.Applying the principles and approaches into practice,we need to study the basic performance after adding the stabilizer,which contain oxidation,pressure,temperature and breaking test.The results are as follows:oxidizability of oxidation breaker remain unchanged after adding carbon black,and greatly improve the storage stability.When the concentration of gel breaker is at 2%and the temperature is 80 ℃,the optimal breaking time is 4h.With the increase of breaker concentration,the performance of gel breaking has improved.The degradative effect of oxidation breaker is similar with the safety and stable oxidation breaker,when the concentration of gel breaker is at 5%,fracturing viscosity for 4mPa s,gel breaking rate is 95.7%and 94.4%respectively,and it has reached the technical indexes.The safe,efficient and stable oxidation breaker will provide security for the future storage,transportation and application.