Experimental Study on the Oxidative Degradation of Coalbed Methane Fracturing Flowback Fluid

This article conducts a water quality analysis of the coalbed methane fracturing flowback fluid in a certain gas field in Yulin. Based on the characteristics of the water quality, four oxidative degradation methods, namely chemical oxidation, electro-Fenton, electro-oxidation, and electrocoagulation, are selected. Taking the removal rate of CODcr as the index, the optimal oxidation conditions for each oxidative method are screened out, and a nanofiltration experiment is carried out on the fluid treated by the optimal method. The results show that: (1) The chemical oxidation method cannot effectively oxidize and degrade the coalbed methane fracturing flowback fluid in a certain gas field in Yulin; (2) Electro-Fenton oxidation can effectively oxidize and degrade this fracturing flowback fluid. When the pH value is 3.0, the current intensity is 9.0 A/m2, and the hydrogen peroxide dosage is 1.0%, after 180 min of electro-Fenton oxidation, the removal rate of CODcr can reach 78.52%; (3) Electro-oxidation cannot effectively oxidize and degrade this fracturing flowback fluid; (4) The best scheme for removing CODcr is electrocoagulation, and the optimal conditions are: pH = 4, current density = 15 A/m2, and the electrocoagulation time is 40 min. Under these conditions, the CODcr value decreases from the original 1441.67 mg/L to 108.33 mg/L, and the removal rate of CODcr is 92.49%. This provides a feasible technical path and important data support.