(304d) Optimal Use of Thermal Membrane Distillation (TMD) for Treatment of Flowback Water

Kaiyu Cao¹, Priscille I. Etoughe², Rajib Mukherjee^2,3, Debalina Sengupta³, Joseph S. Kwon^1,2,3*, Mahmud M. El-Halwagi^1,2,3

1. Artie McFerring Department of Chemical Engineering, Texas A&M Univrsity, College Station, TX
2. Texas A&M Energy Institute, Texas A&M University, College Station, TX
3. Gas and Fuels Research Center, Texas A&M Engineering Experiment Station, College Station, TX

The flow rate of flowback water from hydraulic fracturing varies with time. Most of the water are produced within the first two weeks after hydraulic fracturing is completed. The concentration of total dissolved solids (TDS) in the flowback water also changes with time. For efficient recovery and reuse of flowback water, treatment with thermal membrane distillation (TMD) for the removal of TDS has been found to be the method of choice [1]. Even though flowback water is a continuous process, in this work, for modeling purpose a multi-period optimization problem has been formulated to account for the time-dependent variation of the flow rate and TDS concentration of flowback water, accounting for the time-; hereeach day is treated as a period. Then, we have integrated a TMD unit, considering the largest capacity of flowrate from a well in any given period. An upper limit on the concentration of TDS in the discharged (reject) water is considered to avoid precipitation. Utilizing the field data of flowback water from a given well for each period, the optimization formulation has been solved to determine the maximum period of time for optimal use of TMD, maximizing annualized profit from recovered water per period. Our result shows that it is not profitable to use water recovery beyond first few days, depending on the formation. The performance of the optimization formulation is measured in terms of percentage of recovery and is compared with cost associated with them.

References:

[1] Elsayed, N. A., Barrufet, M. A., Eljack, F. T., & El-Halwagi, M. M. (2015). Optimal design of thermal membrane distillation systems for the treatment of shale gas flowback water. Int J Membr Sci Technol, 2, 1-9.