The Chemical Treatment to Remove Liquid Block in Hydraulic Fractured Well-A Simulation Study with Leak-Off

摘要

The chemical treatment using surfactants/solvents can mitigate the liquid block by wettibility alteration in gas/condensate wells. Recently, its application has been extended from wettibility change in matrix to wettibility alteration in propant in hydraulic fractures and tested in field trials. The leak-off of working fluids into matrix may mitigate the liquid block in the matrix adjacent fracture walls unintentionally. However, it is not clear yet whether the mitigation in matrix from leak-off is significant, compared with the mitigation in the fracture propant, and how this may affect the job design. The experimental setup and associated results was for assessment of the treatment in fracture propant only. In the lab, the leak-off will not affect the flow in fracture since hydrocarbon is injected along the fracture to simulate the production. In reality, the hydrocarbon produce passing through the matrix blocks along fracture. And all previous modeling study and job design has ignored the leak-off. This work shows by simulation of a generic case how the leak-off may affect the design and outcome of the treatment. This work clarifies several important design concerns for the chemical treatment in hydraulic fractured reservoir, which may be extended to natural fractured reservoir as well. This will affect the optimal treatment volume, prediction of outcome and economic evaluation. The leak off may bring little extra benefit from the removal of the block in matrix along fracture walls. But such extra benefit is not significant compared with that in the fracture propant. Due to leak-off, the treatment volume based on fracture volume is not adequate and the associated outcome prediction is optimistic. There is an optimal treatment distance along with fracture that had not been identified in previous study. There is not need to treat the fracture at its full length. Just the opposite, with leak off accounted for the attempt to treat the whole fracture will cost huge volume of working fluid and lead to extra liquid damage. The unintentional matrix treatment due to leak off will cost much more working fluid than the fracture treatment. Therefore, it is necessary to optimize the treatment volume during the job design.