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by Walter Dale
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The consumptive use of water and rising costs of water management are a concern for all in the industry. As a result, produced water and flowback water recycling is starting to gain momentum. The cost of water, including acquisition, transport to the well, transport from the well and disposal, can cost $3-$12 per barrel. Recycling reduces not only the environmental impact but also the cost, especially when one considers the value of using the brine found in produced water and negating additional spend on brine for clay stabilization. However, the industry is still working on developing best practices for recycling.

Currently, three main approaches are being used in the industry:

  1. Bulk mixing of available flowback or produced water with fresh water without treatment;
  2. Removal of Total Dissolved Solids (TDS); and
  3. Targeted treatment of Total Suspended Solids (TSS) along with sound fluid engineering.

There is no question that in time, the best science with the best economics will emerge as the best practice for the industry. And while each of these approaches has some appeal, Halliburton believes that technically sound, sustainable recycling is best achieved through targeted treatment, scale modeling and careful formulation of the resulting fracturing fluids. The following is a brief comparative summary of each of these approaches

Bulk Mixing

One of the widespread recycling methods being implemented in the industry today involves capturing flowback and produced water in the area close to the next planned well site, and then mixing it with fresh water to meet the volume demand of the next completion. This is typically done without any treatment beyond microbial control. This approach certainly has benefits including reduction in fresh water usage, disposal, and transportation. However, what are you really doing when you simply mix these water sources?

One of the largest proppant suppliers, Santrol, performed a study on using weak proppant that crushed under formation pressure and created 5% fines which resulted in a 60% reduction in proppant conductivity.  As fines are essentially TSS, this raises the question of what impact does bulk mixing and passing on TSS in the water have on proppant conductivity? This is exactly what we are studying at Halliburton, and our initial data show a significant reduction in proppant conductivity when elevated TSS levels are introduced in the base fluid. This study will be released in a Society of Petroleum Engineers paper in 2013, but the results should not be surprising when you think about it. And while there remain a number of  factors left to be studied including gas vs. liquids wells, proppant size, and relevant TSS levels, etc. there is little doubt that the effective removal of TSS may have a more positive impact on production than previously considered.

Percent Fines Generated

Water Permeability

Figure 2: Permeability at the stress of 3,000 psi as a function of number of compression cycles using different fluids: produced water treated with CleanWave® technology, and untreated produced water.

TDS Removal

One of the biggest myths in our industry today is that you need to remove the TDS found in produced and flowback waters to make a cross-linked or complex fracturing fluid beyond slick water fracs. Many organizations are spending large amounts of money to remove TDS from produced and flowback waters using various water treatment technologies. Using such technologies is often unnecessary and almost always prohibitively expensive. At Halliburton, we have completed more than 100 stages using cross-linked formulations in recycled waters that contain TDS levels greater than 280,000 ppm.

How have we done that?  Mainly by adjustments in fluid chemistry, which is far more cost effective to apply than TDS-removal technologies to large volumes of water. When one considers that, depending on the TDS-removal technology chosen, the operator may be required to handle and dispose of additional treatment waste streams, the total cost of TDS removal becomes even more expensive. The graph below shows various technical approaches and total cost economics for recycling. The data below is from an internal study with all costs of inputs and waste streams needed and set to a dollar-per-barrel value. As is evident from the chart, TDS-removal technologies simply do not compare well on a dollar-for-dollar basis, and, as we will discuss in more detail below, are not necessary to create usable fracturing fluids.

Economic Considerations

Figure 3: Economic considerations of various water technologies for recycle in fracturing fluids

Targeted Treatment with Fluid Modifications

Advancements in fluid chemistry will allow the industry to recycle at a lower per-well price point. I’ve already stated the importance of the removal of TSS as a function of proppant conductivity and how this trend is starting to be further understood in the industry. Flowback water is typically very high in TSS and low in TDS, while produced water is very high in TDS with moderate TSS values. Using the produced water stream as well as the flowback stream can have significant economic and environmental benefits when done correctly.

The ions found within the waters are recycled so one can then select the water treatment technology and fluid chemistry adjustments that will deliver the desired fluid properties and successful recycling. Scale modeling must also occur in these projects. Removal of the heavy metals changes the scale profile of the waters to be used and allows for recycling using cross-linked fluids. Below is the rheology on wells found in the Permian Basin where using Halliburton’s CleanWave® treatment technology and fluid modifications has allowed one customer to re-use 100% of their produced water to complete over 98 stages. We have also had success in proving this concept in the Bakken, an area where conventional wisdom and even an earlier study wrongly concluded that the produced water in this basin could not be used for complex cross-linked fluid formulation.

Successful Recycling Project

Figure 4: Water and fluid data for successful cross-linked recycling project

Benefits of Recycling

Our goal is to provide water management and recycling options that both further the sustainable development of our industry and save our customers money. Our Total Water Management Solutions technologies and practices allow the industry to utilize what was once a waste stream as part of their supply chain for unconventional development. Not only does this reduce the environmental impact of our industry, it is also good for the bottom line. The graph below shows the overall economic benefits of recycling.

Benefits of Water Recycling

Figure 5. Benefits of Water Recycling

Our customers have implemented recycling programs and achieved significant savings per well without jeopardizing well productivity by utilizing our Total Water Management Solutions technologies. The key to this net positive impact on recycling projects lies in the selection of a technology able to use the available waste streams and turn them into a stable fracturing fluid that does not impact well productivity. In addition, developing quality logistical engineering based on proximity of available recycled water supplies helps reduce the cost of transportation of water both to the wellsite as base fluid and from the wellsite as waste. When you add the costs of treatment and often storage to the equation, the net economics for recycling, when it is done correctly, are positive and come with environmental benefits.

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Walter DaleAbout Walter Dale
Global Business Development Manager – Water Solutions

Walter Dale is the Global Business Development Manager for Halliburton’s Water Solutions sub-product service line. Based in Houston, Texas, he has 14 years of technical water treatment experience – a large portion of that time spent leading teams and aligning technologies to enhance oil-water separations in the South Central U.S. region and in the Canadian oil sands.

Mr. Dale joined Halliburton in 2011. He began his career as a technical specialist with BetzDearborn, treating wastewater systems in Texas. After GE acquired BetzDearborn, Mr. Dale served GE as a regional manager for the South Central U.S., then later as a general manager for Western Canada with a focus on the oil sands. While in Canada, he worked with the Canadian government on behalf of industry to align sustainable development water strategies for the oil and gas market.

Mr. Dale holds a Bachelor of Science degree in chemistry from Stephen F. Austin State University in Texas.

 

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