If you had a chance to meet with our completions experts at the 3rd Annual Cabot Community, they would have told you about what does into our hydraulic fracturing fluids and how we fracture a well. You also would have seen these free FracFocus.org buckets, filled with beach goodies and actual frac sand, which we’ll explain in this post.
Today, we’ll recap last week’s #AskCabot question, “What is frac fluid” by explaining our partnership with FracFocus, a national chemical disclosure registry, and by explaining the components of hydraulic fracturing frac-fluid. Last week, we answered the #AskCabot question with “Water and sand make up more than 99 percent of the fluid. Less than one percent is chemical additives.” So let’s take a closer look at those components.
Yesterday’s Drilling Down post focused on our commitment to recycling as much water used in the hydraulic fracturing process as possible. The fracturing process requires thousands of pounds of pressure to actually break the rock and allow natural gas to come to the surface. Cabot uses 3.9 million gallons of water to complete this process at each well. One of the main purposes of the fracturing fluid as a whole is to carry the sand or propant into the formation so that it can literally prop open fractures in the rock for fuel to travel out.
Cabot uses a “closed loop system” to capture and contain all of the fluids recovered from our drilling, completion and production operations. After recovered water is transported from a well pad to the nearby ComTech Industries, Inc. treatment facility, the recycling process involves three key stages including the mix tank, the primary clarifier tank and the final clarifier tank. Reference yesterday’s post for visuals and further explanation.
According to FracFocus, “because the multi-stage fracturing of a single horizontal shale gas well can use several million gallons of water, it is critical that large quantities of relatively fresh water be reasonably available. The quality of the water is very important because impurities can reduce the efficiency of the additives used in the process.”
Though that might seem like a lot of water per well, our recycling efforts allow us to treat the returned water and use it again in the fracturing of a different well. Additionally, water use from the oil and gas industry accounts for only 1 percent of all water used by industry in the United States.
That sand in the FracFocus bucket isn’t your typical beach sand. It is specially formulated to “prop” open the Shale so that hydrocarbons can flow into the pipe. Bruce Brown, Senior Geologist for Non-Metallic and Industrial Minerals, said, “The sand is mixed with water and then pumped at very high pressure into oil and natural gas wells. The slurry of sand and water blasts apart the rock and then the strong, round sand grains hold open the fractures so the oil and natural gas can make their way to the surface.”
Transloading.org, a bulk material service for the Marcellus Shale industry, writes,“ Frac sand is ordered by size and type. The reason there are so many different specifications to this material is because different size sand particles work differently in the fracing process. The foreman of the wellbore knows what will work best for each particular well they are extracting the oil or natural gas from. If the wrong type or size of frac sand is used, the end results will be different. It is true that all frac sand is used for the same purpose. The difference lies in the rock bed and how it interacts with it.”
Much misinformation is spread about chemical usage in the process of hydraulic fracturing, but that misinformation typically comes from a genuinely uneducated perspective or of fear from those opposed to hydraulic fracturing. In fact, a large number of the questions Cabot received at the Picnic Saturday, July 21, were about the chemicals used.
In reality, less than one percent of all the fluid that we pump down a well is composed of chemical additives. According to FracFocus, “Chemicals serve many functions in hydraulic fracturing. From limiting the growth of bacteria to preventing corrosion of the well casing, chemicals are needed to insure that the fracturing job is effective and efficient.”
FracFocus also communicates that though the industry uses a number of compounds in frac fluid, “any single fracturing job would only use a few of the available additives.” For example, the chart shown below “represents 12 additives used, covering the range of possible functions that could be built into a fracturing fluid.”