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Question: Please answer all the following question since all parts are related to each other. Water budget ...
Please answer all the following question since all parts are related to each other.
Water budget for shale energy development
Nittany Energy Company is interested in developing shale gas in northern Cen County. In order to efficiently develop energy resources in this area the company will need to draw water from a nearby stream and they are interested in understanding how much available water they can withdraw. Based on available USGS gages the annual average daily flow of the stream is 150 million gallons per day. The regulator will allow the company to withdraw 1% of the annual average daily flow each day. Each proposed well will require 4.5 million gallons for hydraulic fracturing. Answer the following questions.
1. What volume of water (in gallons) can Nittany Energy Company withdraw from the stream each day?
2. How many days will it take to accrue the necessary volume of water from the stream to fracture one single well?
3. About how many wells could be theoretically fractured in one year based on withdrawal limits?
4. Each well will return 5% of the fluids injected into the well as flowback. How much flowback is expected from each well? (Answer in gallons)
5. One-third of the water used to fracture each well is recycled flowback. What volume of the fracturing fluid injected is recycled flowback? What volume would be fresh water? (Answer in gallons)
6. Assuming the company fractures 20 wells in a year, what will be their total water use and how much flowback will they collect if 5% returns (as presented in question 4)? (Assume there is no recycled water for this question)
7. Based on question 6, assume the company recycles 90% of their flowback in a year, how much less fresh water will they need to withdraw?
Explanation / Answer
1.
Annual average daily flow = 150 million gallons per day
Amount of withdrawal permitted = 1% of the Annual average daily flow
= 1/100 × 150 = 1.5 million gallons per day
Now, 1 million gallons per day = 1,000,000 gallon per day
Thus, the required volume of water = 1.5 × 1,000,000 = 1,500,000 gallons
2. Water required for hydraulic fracturing of one single well = 4.5 million gallons
Water drawn from the river per day = 1.5 million gallons
Days required for acquiring water sufficient for hydraulic fracturing of one single well:
= (4.5 million gallons)/(1.5 million gallons)
= 3 days
3. In one year water drawn from the stream as per the withdrawal limits = 365 x 1.5 million gallons = 547.5 million gallons
Water required for hydraulic fracturing of one single well = 4.5 million gallons
Number of well that can be fractured using the water from the stream = (547.5 million gallons)/(4.5 million gallons)
Number of well that can be fractured using the water from the stream= 121.66 or 121 wells
4. Water required for hydraulic fracturing of one single well = 4.5 million gallons = 1,500,000 gallons
Flowback = 5 percent of the water injected while hydro fracturing
Volume of flowback = (5/100) x 4,500,000 gallons =225,000 gallons
5. Volume of recycled flowback = 1/3 of water required for hydraulic fracturing of one single well
Volume of recycled flowback = 1/3 x 1,500,000 gallons = 500,000 gallons
Volume of fresh water = water required for hydraulic fracturing of one single well - volume of recycled flowback
Volume of fresh water = 1,500,000 gallons - 500,000 gallons = 1,000,000 gallons
6. Total water use = Water required by company to fractures 20 wells in a year:
= 20 x 1,500,000 gallons = 30,000,000 gallons or 30 million gallons
Volume of flowback from 20 wells = 225,000 x 20 =4,500,000 gallons or 4.5 million gallons
7.
If the company recycle 90% of their flowback in a year, then they need = 4.5 x (90/100) million gallons, less water
Therefore if the company recycle 90% of their flowback in a year, then they need 4.05 million gallons or 4,050,000 less water.
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