Effect of Shale Fracturing Cleanup Agents Stepwise Addition to Fluid Recovery

The effect of applying method for cleanup agent to fluid recovery is still ambiguous. Three cleanup agents were chosen. Basing on the method of gas drainage, the simulation and evaluation through saturated by stage was set up and the results proved that the drainage ratio can be affected significantly by the variation of applying method. The drainage ratio of stepwise addition was obviously lower than the case of the addition in the whole process. But the drainage ratio of stepwise addition for CT5-13 was nearly the same as the case of the addition in the whole process. Besides, the mechanism was discussed by the variation of surface tension and the contact angle. Basing on the results of CT5-13 with microemulsion and non-oil structure, the formation of microemulsion structure of CT5-13 can be an important mechanism for ensuring the flow-back performance in the case of stepwise addition.