OUR GREAT MINDS

    by Bob Kimbell

    Water-Management In Shale Plays

    Globally, the energy sector has transformed itself in the last ten years, developing unconventional oil and gas resources through two technologies: horizontal drilling and hydraulic fracturing. Water is integral to development, from sourcing and transportation to treatment and reuse to disposal. Thus, a water-management plan that optimizes each use of water is important and significantly reduces costs.

    The greatest opportunity for cost savings is with transportation.

    Recycling and reuse of produced water sources are ways to reduce transportation costs as well as truck traffic. This approach is common in the Appalachian region of Pennsylvania, but has only recently been seriously considered in other basins across the U.S. Several water-recycling technologies are available and are constantly being refined. Treatment of water for recycling and reuse generally aims to remove petroleum hydrocarbons, suspended solids, bacteria, and polymers.

    The values in red represent water volumes for the more conventional approach without treatment and recycle, while the values in blue show the effect on water volumes with the recycle of flowback water. In each case, we assume 300,000 bbl of water are required to frack each well and the flowback fraction is 25 percent of the fracking volume. For the recycle approach, we assume 90 percent of flowback water is treated for reuse and 10 percent is disposed offsite as non-recoverable waste.

    Unit costs for each water-management step are based on experience in Texas and represent an example of potential cost savings. The approach that treats flowback water at the wellhead for recycle and reuse in the next frack reduces fresh water makeup demand from 300,000 to 232,500 bbl. Similarly, the volume of water requiring offsite hauling and disposal drops from 75,000 to only 7,500 bbl, a reduction of 450 truckloads to and from the site. The cost to source, transport, store, and dispose of water without recycle is $750,000 per well, while the cost for treating and recycling is $547,500. Thus, the recycle approach reduces water-related well costs by $202,500 per well. This may seem insignificant considering the cost of drilling a well, but when drilling 1,000 wells across a field, the savings are more than $200 million.

    There are many ways to best manage water in shale plays. Trucking is generally the most expensive and increases liability and environmental impacts, so incorporating treatment for recycling and reuse is one way to improve economics and reduce truck traffic. Overall, careful planning, evaluation of options, and selection of the best treatment technology will lead to optimal water management.

    The three-day National RE3 Conference to be held in Philadelphia in January 2014 will delve further into regarding treatment and management of contaminated soil, groundwater, and waste streams as it relates to daily operations, remediation, and redevelopment of oil and gas sites.

    Bob Kimball, VP of the Industrial Services Group of CDM Smith, a global consulting, engineering, construction and operations firm offering a full range of services in water, the environment, transportation, energy and facilities.

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