Solaris Water Midstream has begun operations at its newest large-scale water-reuse complex in New Mexico, the Eddy State Complex. The complex can supply 300,000 B/D of recycled produced water for operators in the northern Delaware Basin. Th complex adds to the company’s ongoing recycling operations at its Lobo Reuse Complex in Eddy County and the Bronco Reuse Complex in Lea County. Two additional water-recycling centers are expected to be completed by December. When all five water-reuse complexes are operating, Solaris Water will have the capacity to recycle more than 900,000 B/D of produced water, with over 3 million bbl of adjacent storage capacity.

The well count and completion intensity of US tight oil and gas operations have grown in recent years, and rising pressure from environmental regulations means that produced water management has become a key focus for operators. While storage and logistics are critical elements of the viability of water reuse, if the water chemistry is not fit for gel fracturing formulations, it will not matter how much is stored in centrally located impoundments. This paper reports on performance of an advanced MVR system in north-central Texas. With inconsistent inlet water quality being the rule rather than the exception, sizing and operational considerations of the treatment system components must vary accordingly to make the most economic sense. The demands for the fresh water used in many hydraulic fracturing operations are placing pressure on water sources in some regions of the United States.

Case studies of mill-out operations in the Permian Basin which evaluate chemical programs and processes used. Results show how existing processes and chemicals used or lack thereof, can affect equipment and undo the preventative chemical treatments used during the hydraulic fracturing process.

The study looks at field water testing performed during various mill-out operations and considered workover rig vs coiled tubing, equipment set up, water & chemicals used, and operational challenges. Water analyses were completed on the injection water and returns at various intervals of the mill-out. Effectiveness of chemical treatment was also monitored when biocide was used.

Field case studies of horizontal wells for two operators in the Permian Basin are presented. Wells were milled-out utilizing workover rigs or coiled tubing units. Testing results show the impact of equipment setup and operations process on the water quality and efficiency of the chemicals used. Water fouling was prevalent in all cases, with coiled tubing jobs showing the highest degree of water contamination and chemical inefficiency. Changes in the water treatment program during operations showed significant improvement and sustainable results. Potential corrosion of the work string due to water fouling and water composition were also observed. The effects of changes to chemical dosages were also monitored. This was important because it identified operational improvements that can reduce equipment replacement costs, reduce chemical overuse and help protect wells from fouling due to high bacteria.

These case study provides a comprehensive review of mill-out operations, which provides guidelines for improving chemical efficiency and potential of extending life of the work string.

Case studies of mill-out operations in the Permian Basin which evaluate chemical programs and processes used. Results show how existing processes and chemicals used or lack thereof, can affect equipment and undo the preventative chemical treatments used during the hydraulic fracturing process. The study looks at field water testing performed during various mill-out operations and considered workover rig vs coiled tubing, equipment set up, water & chemicals used, and operational challenges. Water analyses were completed on the injection water and returns at various intervals of the mill-out. Effectiveness of chemical treatment was also monitored when biocide was used.

Field case studies of horizontal wells for two operators in the Permian Basin are presented. Wells were milled-out utilizing workover rigs or coiled tubing units. Testing results show the impact of equipment setup and operations process on the water quality and efficiency of the chemicals used. Water fouling was prevalent in all cases, with coiled tubing jobs showing the highest degree of water contamination and chemical inefficiency. Changes in the water treatment program during operations showed significant improvement and sustainable results. Potential corrosion of the work string due to water fouling and water composition were also observed. The effects of changes to chemical dosages were also monitored. This was important because it identified operational improvements that can reduce equipment replacement costs, reduce chemical overuse and help protect wells from fouling due to high bacteria. These case study provides a comprehensive review of mill-out operations, which provides guidelines for improving chemical efficiency and potential of extending life of the work string.

Hydraulic fracturing in the Marcellus Shale play has moved to produced water only scenarios because of prohibitive water disposal costs. Well completion under produced water only conditions increases the demand on chemical additive performance. In addition, water reuse selects deleterious microorganisms through natural selection, which may increase the likelihood of formation souring. Conventional biocides are typically used to mitigate these risks, but to some extent, they present health, safety, and environmental (HSE) concerns. In addition, several conventional biocides have side reactions with sulfide, notably tetrakis(hydroxymethyl)phosphonium sulfate (THPS) and 2,2-dibromo-3-nitrilopropionamide (DBNPA). This paper describes an improved method for the effective control of deleterious microorganisms without the use of conventional biocides.

An environmentally friendly system that includes nitrate-reducing bacteria (NRB) coupled with nitrate co-introduction was previously shown to mitigate souring as effectively as a biocide alternative for more than 1,000 assets. The NRB inhibit growth of the deleterious sulfate-reducing bacteria (SRB) primarily by competing for the available carbon source if the source is limited. This paper describes an improved NRB/nitrate system that incorporates a sulfate analog, which presumably inhibits dissimilatory sulfate reduction and enhances mitigation. Laboratory experiments were performed to measure the amount of hydrogen sulfide (H₂S) produced in field brine samples inoculated with SRB. The improved NRB/nitrate system was shown to inhibit the production of H₂S under worst-case scenarios in laboratory competitive exclusion experiments.

Results for the new treatment at four trial wells are presented. Sulfate-reducing bacteria populations, acid-reducing bacteria populations, and a gaseous H₂S concentration were monitored over three months and were found to satisfy the operator's set key performance indicators. Overall, the amount of chemical required for treatment was reduced for this improved system, which substantially reduced the operator costs to treat the wells.

The combination of chemistries with mutually exclusive cellular targets highlights the value of synergistic effects, specifically reducing system cost to treat while retaining low aquatic toxicity, as compared to traditional biocides used in the oilfield.

1.0 Summary

The reuse of produced water for hydraulic fracturing operations has both environmental and economic benefits. A demonstration scale study using a high-rate clarification process was conducted in the Delaware Basin to evaluate technical feasibility and cost-effectiveness of treating produced water to remove dissolved iron and hardness. Pilot studies were conducted in following three phases to prepare designer's water to match with multiple types of fracturing fluid.

• Phase 1: Iron removal - near neutral pH treatment (oxidation using peroxide)
• Phase 2: Iron removal and partial hardness removal - pH 9.5 treatment (partial softening using caustic hydroxide)
• Phase 3: Complete removal of hardness ions - pH 11.5 treatment (complete softening using caustic soda and soda ash)

The demonstration study showed that a high-rate clarifier technology, capable of handling elevated levels of suspended solids, is suitable for reuse applications in the operating conditions of the Permian hydraulic fracturing. For iron removal during Phase 1 treatment, oxidation with peroxide is holistically more cost effective than the High pH method. This is primarily due to lower chemical and sludge handling costs. On-site dewatering of sludge allowed the solids to pass paint filter test, a requirement for sludge hauling to a certified landfill. Phase 2 treatment (at pH 9.5) removed 95% of magnesium in addition to near complete removal of dissolved iron. Therefore, Phase 2 treatment is expected to have much lower scaling tendency when completing well with pH 9.5 or higher pH crosslink fluid. No significant differences between Phase 1 and Phase 2 are expected for Slick Water completion fluids. While Phase 3 treatment can remove more than 99% of hardness ions, it is not practical to implement for Delaware produced water given the high costs of chemical usage and sludge disposal.

Damage testing was conducted with the raw produced water, Phase 1 water and Phase 2 water with various fracturing fluid systems. A produced water slickwater system was identified as causing the least amount of proppant pack damage in tests described in this study when used with Phase 1 water. Additionally, produced water minimizes rock softening as compared to fresh water systems. Maintaining formation hardness would lead to less proppant embedment. Less proppant embedment would enhance fracture conductivity in the proppant pack.

Produced water reuse can be a valuable strategy for operators because lowering their water footprint helps promote sustainability. With oil production rising in the Permian, companies are producing more water in relatively small areas, leading to heavy investments in water infrastructure and water recycling. In a presentation held at the Permian Basin Water in Energy Conference, Tyler Hussey, a water resource engineer at Apache Corp., examined the process companies go through when deciding on a proper recycling system for their operations. Last year, recycled produced water made up more than 40% of Apache’s hydraulic fracturing water usage in the Midland Basin. Hussey said that the company’s goal this year is to raise that total closer to 50% and that his personal goal is to raise it as high as possible.

Produced water reuse can be a valuable strategy for operators because lowering their water footprint helps promote sustainability. With oil production rising in the Permian, companies are producing more water in relatively small areas, leading to heavy investments in water infrastructure and water recycling. In a presentation held at the Permian Basin Water in Energy Conference, Tyler Hussey, a water resource engineer at Apache Corp., examined the process companies go through when deciding on a proper recycling system for their operations. Last year, recycled produced water made up more than 40% of Apache’s hydraulic fracturing water usage in the Midland Basin. However, there are several additional factors that influence the scope and scale of recycling.

Produced water reuse can be a valuable strategy for operators because lowering their water footprint helps promote sustainability. With oil production rising in the Permian, companies are producing more water in relatively small areas, leading to heavy investments in water infrastructure and water recycling. In a presentation held at the Permian Basin Water in Energy Conference, Tyler Hussey, a water resource engineer at Apache Corp., examined the process companies go through when deciding on a proper recycling system for their operations. Last year, recycled produced water made up more than 40% of Apache’s frac water usage in the Midland Basin. Hussey said that the company’s goal this year is to raise that total closer to 50%, and that his personal goal is to raise it as high as possible.