JV TASK 7-FIELD APPLICATION OF THE FREEZE-THAW/EVAPORATION (FTE) PROCESS FOR THE TREATMENT OF NATURAL GAS PRODUCED WATER IN WYOMING

Abstract

The freeze-thaw/evaporation (FTE{reg_sign}) process treats oil and gas produced water so that the water can be beneficially used. The FTE{reg_sign} process is the coupling of evaporation and freeze-crystallization, and in climates where subfreezing temperatures seasonally occur, this coupling improves process economics compared to evaporation alone. An added benefit of the process is that water of a quality suited for a variety of beneficial uses is produced. The evolution, from concept to successful commercial deployment, of the FTE{reg_sign} process for the treatment of natural gas produced water has now been completed. In this document, the histories of two individual commercial deployments of the FTE{reg_sign} process are discussed. In Wyoming, as in many other states, the permitting and regulation of oil and gas produced water disposal and/or treatment facilities depend upon the legal relationship between owners of the facility and the owners of wells from which the water is produced. An ''owner-operated'' facility is regulated by the Wyoming Oil and Gas Conservation Commission (WOGCC) and is defined as an entity which only processes water which comes from the wells in fields of which they have an equity interest. However, if a facility processes water from wells in which the owners of the facility have no equity interest, the facility is considered a ''commercial'' facility and is permitted and regulated by the Wyoming Department of Environmental Quality. For this reason, of the two commercial FTE{reg_sign} process deployments discussed in this document, one is related to an ''owner-operated'' facility, and the other relates to a ''commercial'' facility. Case 1 summarizes the permitting, design, construction, operation, and performance of the FTE{reg_sign} process at an ''owner-operated'' facility located in the Jonah Field of southwestern Wyoming. This facility was originally owned by the McMurry Oil Company and was later purchased by the Alberta Energy Company (now EnCana). Case 2 summarizes the permitting, design, construction, operation, and performance at a ''commercial'' FTE{reg_sign} facility located in the Great Divide Basin of south central Wyoming. Permits required for the construction and operation of each facility are described in detail. The respective qualities of each feed water, treated water, and concentrate stream are presented along with the relative yields of treated water and concentrate at each facility. Treated water from the owner-operated facility has been beneficially used in drilling and dust abatement, and treated water from the commercial facility has been used for dust abatement, construction, and land application. The permitting requirements and evaluation of beneficial use of the water at each facility are discussed. The results of this research confirm that the FTE{reg_sign} process is economic at a commercial-scale for the treatment and disposal of natural gas produced water in Wyoming. Further, the treated water produced from the process is of a quality suitable for beneficial uses such as irrigation, drilling mix, wildlife or livestock watering, and/or dust abatement on local roads.