Page 94 - Occupational Health & Safety, June 2019

OIL & GAS
etc.) are collected in addition to chemical composition. Lab results are an essential component to the success of a recycling/ reuse program.
Determine accurate volume data from your wells. Compare multiple sources of where the volumes are reported (SCADA tank level measurements, separator meters, water hauling receipts, injection receipts). On occasion, the volumes reported by the water hauler are not as accurate as the mea- surements pulled from SCADA tank read- ings. Take the time to compare the two. Again, measure at multiple times during wells’ life span to develop predictive pat- terns as wells age. Seasonal trends may also be apparent after the data collection.
Step Two: Evaluate the Options
Review the water quality results and deter- mine a list of reuse options, starting with a list of what can be reused with minimum treatment: evaporation beds, crop or golf course irrigation, dust control, watering for pad reclamation, rangeland restoration, livestock watering.
If the water quality is too high in con- taminant concentration, reuse options will require treatment before use. These usually have a more industrial application: cooling tower water, pulp and paper mill water use, cement and concrete mixing, mining flood fluids, and soluble-mineral extraction fluids.
The production company will receive the most economic benefit if there is a reuse application that can be used directly on site: drilling mud fluid additive, hydraulic frac- turing fluid components, ten-pound brine (heavy brine) for workovers, enhanced oil recovery (EOR) fluids in waterfloods or steamfloods, soil cement fluids for pad construction. Exact treatments required to reach usable water quality will vary consid- erably but start with settling and filtration. The water chemistry will dictate what treat- ment is necessary.
When evaluating the reuse options, don’t disregard the water’s physical charac- teristics. Produced water with a sufficient density can be a viable reuse of heavy brine water, once disinfected properly. Addition- ally, produced water can come up-hole at temperatures near boiling (200o F). This available energy can be used as heat during distillation, field evaporation, steam pro- duction, and electric generation.
Don’t forget to evaluate the physical in-
puts of the technology: How will it be pow- ered, will it work remotely, what volumes can it handle, is it robust, will wells need to be shut-in if something fails? Work through the large possibilities of actual operation.
Step Three: Evaluate the Costs
Determining the costs for reuse is the most difficult part, because the water volumes and chemistry will vary. It is hard to bud- get for the considerable variation of nature. Start with the costs of fresh water sourcing. Water supply costs are often a driving fac- tor of a reuse/recycling plan. Research the costs of the current disposal plan: treat- ment, transport, storage. Are there any contractual minimum volume require- ments? Check with accounting to see how the fresh water purchasing and wastewater disposal fees are distributed among the lease and partners. Determine your com- pany’s actual cost.
Two methods to help contain treatment costs are to field-manage the water qual- ity and to supervise the concentrations of the downhole chem used. After consider- ing the results of the chemical sampling program of the wells, manage your gather- ing system by directing the water to where there is one available “cleaner” source of produced water. Instruct the gathering sys- tem or water haulers to load one of your storage facilities with less heavily contami- nated produced water to use as your source material for the reusable water. Also, man- age the wells’ downhole paraffin thinners and descaling fluids so that it is not foul- ing the “better” produced water collection. If sample results are exceptionally high in methanols (or other constituents of your downhole chem), reduce the rate or load. The results are showing it is just coming back up hole unspent.
Step Four : Evaluate the Reality
After it has been determined what waste water reuse options are physically possible and affordable, the viability determina- tion isn’t over until the regulatory, envi- ronmental, and social impacts have been determined. Will the regulators buy in? Is this going to require a year-long permit- ting process? Does the treatment process use combustion to provide clean water? Will the process itself require an addi- tional air permit? Will the limits of the air permit be achievable? (NAAQS lb./hr. is a
tough standard to meet for some sources of combustion). What other air, water, or wastes issues will be generated? Are there measurable social impacts due to the recy- cling—noise, traffic, explosive atmospheres in close proximity to neighborhoods, etc.?
Fortunately, as more reuse is put into place, expenses will begin to lower due to economies of scale. It is reported by the Global Petroleum Research Institute that half of the produced water in Texas is less than 10,000 ppm TDS. That is a significant useable resource. However, once produced water has an economic benefit, there are mineral rights owner issues that may need to be contractually addressed prior to use, so plan ahead.
Preparing the Study Pays Dividends
There are many more decisions to make to refine the type of reuse possible for an operator (such as disinfection), but this four-step process outlines a good start to determine what process warrants further scrutiny. Of course, economics is usually the basis of any reuse decision, but prepar- ing a reuse viability study in advance of a fresh water shortfall or a disposal issue will give the operator an advantage when it is necessary to react to change.
Laura Slansky is a Certified Hazardous Materials Manager (CHMM) and a Certi- fied Safety Professional (CSP) working at a major midstream company in Denver. She has been in the oil and gas industry for more than seven years, with six years of prior con- sulting experience. She can be reached at lhslansky@gmail.com.
REFERENCES
1. Allison, E. 2018. Petroleum and The Environment
American Geosciences Institute, https://www. americangeosciences.org/critical-issues/petro- leum-environment (accessed April 20, 2019).
2. Matthews, C. 2018. The Next Big Bet in Frack- ing: Water. Wall Street Journal, 22 August 2018, https://www.wsj.com/articles/the-next-big-bet- in-fracking-water-1534930200 (accessed Nov. 14, 2018).
3. Burnett, D. 2018. Potential for Beneficial Use of Oil and Gas Produced Water, https://www. researchgate.net/publication/237345333_Po- tential_for_Beneficial_Use_of_Oil_and_Gas_ Produced_Water (accessed Nov. 14, 2018).
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