Aeration is an answer.
Halcon Resources Corporation (Halcon) is an independent energy company focused on the acquisition, production, exploration and development of liquid-rich assets in the Delaware Basin. It was able to build a “premier ~60,000-acre position in the Delaware Basin for less than $19,000/net acre” with current production > 13,500 Boe/d (barrels of oil equivalent per day). Halcon’s Delaware Basin position includes:
• Monument Draw (Ward County) with ~22,479 acres
• West Quito Draw (Ward County) with ~10,622 acres
• Hackberry Draw (Pecos County) with ~27,115 acres
For the second half of 2018, Halcon will be focusing on development, delineation and gaining scale. Although recently dropping one rig, they plan on continuing with three operated rigs for the remainder of the year. As part of Halcon’s program, they will be working with long lateral development, transitioning to multi-well pads, testing upside pay zones, performing optimal well-spacing tests, completing vertical pilot wells and using shuttle logs to determine optimal geosteering and frac design. They plan on improving efficiencies by reducing drilling delays, utilizing local proppant sources in brown sand and optimizing completions with innovative technologies and techniques. Production will be maximized by installing jet pumps for artificial lift, removing production bottlenecks and reducing downtime through proactive maintenance.
An important part of Halcon’s plan is their produced-water recycling program. Since beginning their Delaware Basin operations ~70 percent of the water used for completions has come from this program. At least 75 percent of their water in 2018 will be recycled produced water. Their goal is to be at or near 100 percent by the start of 2019. Halcon will continue to develop produced-water recycling and injection capacity, while maintaining capacity above their forecast.
Another important strategy has been the cost benefit of owning water infrastructure versus third-party outsourcing. Halcon has realized 60-percent savings in produced-water disposal and water sourcing using Halcon-owned resources versus those of third parties.
Cost Benefits of Halcon-Owned Resources
|Area||Surface Acreage Held||Water Pipelines in Place||Produced-Water Capacity||Freshwater Capacity||Water-Storage Capacity|
20,000 bwpd (barrels of water per day) of injection (3 wells)
40,000 bwpd of recycling (1 facility)
10 wells with 60,000 bwpd of capacity
Additional capacity available
900,000 bbls (barrels) of produced/recycled water
1,100,000 bbls of freshwater storage
|West Quito Draw||
Acquiring surface now
Planning SWD wells now
Planning freshwater wells now
Construction beginning shortly
45,000 bwpd of injection (3 wells)
120,000 bwpd of recycling (3 facilities)
4 wells with 40,000 bwpd of capacity
Additional capacity available
2,700,000 bbls of produced/recycled-water storage
1,000,000 bbls of freshwater storage
This strategy included the development of a produced-water recycling program that incorporated a company-owned produced-water operation. Halcon contracted with Hydrozonix to design and install a complete recycling system. The first one installed was an automated oxidation system, HYDRO3CIDE. It pretreated the produced water going into the Halcon gun barrel oil/water system that included centrifugal solids separation.
This supplied some of its ozone capacity to treat via slipstream the influent produced water going into the combination of centrifugal separator then oil/water separation tanks. The effluent of the centrifugal separation system and oil/water separators is discharged into the primary pit. Water from this primary pit is recirculated through the same oxidation system. This one system replaced chemicals for bacteria, iron and sulfide control in the oil/water separation tanks while eliminating chemicals for pit treatments at a significant savings.
The fully automated HYDRO3CIDE uses ozone. The system only needs electricity and air. Ozone degrades back into oxygen so no harmful byproducts are formed that can interfere with the frac formula. Ozone is a strong oxidant that is effective for bacteria, iron and sulfide control. It requires less than half the amount of ozone compared to chlorine dioxide and even less compared to sodium hypochlorite.
The automation integrates with the existing pump systems allowing the automation to operate the pump, providing control over the oxidation-delivery rate. The automation means the system can be monitored and controlled from any PC or from your cellphone. It’s possible to monitor the performance of the system and the produced-water quality going through and out.
You can also operate the system remotely and turn it off or any individual components including the pumps. Data is stored for customized reports and trend analysis. This dual-purpose oxidation provides bacterial control in the oil/water separation system when going to the injection well or pretreatment to the fluid as it enters the primary produced-water pits for storage.
The produced-water storage pits were equipped with Hydrozonix Hydro-Air aeration systems. Aeration meant the produced-water quality was maintained while in storage. A mixing aerator keeps the pits from stratifying while introducing oxygen in the water using air from a blower. Oxygen is an oxidant allowing any residual iron that remains untreated from the oxidation system to be oxidized while stopping bacteria growth.
The aeration system consists of air-diffusion pods with an educator-type tube above them so that the surround water is channeled and mixed with the diffused air. Each pod is attached to a buoy so it can be removed and inspected, even when the pit is full of produced water.
A deployment dock installs or retrieves aeration pods even within a full pit. The dock is equipped with windsocks and a self-contained breathing apparatus (SCBA) in the event of a hydrogen-sulfide release. As part of the deployment procedure, water is analyzed to ensure there is no hydrogen sulfide in the produced-water pit prior to deploying the dock. All personnel on the deployment dock also have their own personal hydrogen-sulfide detector in addition to the SCBA on the dock itself.
HYDRO-AIR—PORTABLE AND RELOCATABLE
The entire Hydro-Air system is portable and relocatable. The blower is on a trailer, and the individual pods and hoses can be retrieved and moved to additional pits when activity subsides in one area and increases in others. This is a unique feature to the aeration system.
A failure of most oil-field aeration operations is they don’t anticipate the high oxygen demand of produced water and supply far less air than required. An oxygen-demand test is critical to the initial sizing and design of the aeration system. This initial test is either never done or is based on some other metric like water volume and ignores the high oxygen demand of produced water as compared to freshwater sources.
The other most frequent problem is passive submersible systems that get buried or clogged with suspended solids. Even with an effective solids-control strategy prior to discharge to pits, the dry and dusty Permian Basin tends to create a lot of dust loading, adding suspended solids back into produced-water pits. This constant dust loading settles to the bottom, clogging submerged bubble tubing and burying passive diffusers. The aeration systems are mixing aerators that keep the area surrounding the mixer/aerators free of solids. Because of the relocatable design, inspection and verifying the performance of individual mixer/aerator pods are possible.
Hydro-Air becomes a better alternative to chemical-pit treatments at a significantly lower cost. And it provides other benefits that pit treatments can’t, like pit homogenization or mixing to prevent stratification. Stratification will concentrate chlorides, which when that produced water is recycled, interferes with the friction reducer, requiring a higher concentration of the reducer, driving up completion costs. Aeration eliminates chemical storage, and the potential of spills and safety hazards of chemical storage.
Pit-treatment costs aren’t predictable. Pits may require multiple treatments as chemicals degrade in sunlight or are just consumed by the demand of the produced water. Ongoing monitoring of bacteria is required to determine the number of chemical-pit treatments. With a functioning aeration system, a quick dissolved-oxygen test will tell whether there is adequate air and produced-water quality. The other benefit of mixing aerators is the mixing action prevents icing during winter months.
The combination of HYDRO3CIDE and Hydro-Air complements the existing Halcon solids control and oil/water separation system and at a lower cost than the development of a saltwater-disposal well, driving the cost of recycling produced water lower than that of disposal. Combining these savings with the replacement of fresh/brackish source water with recycled produced water provides even further savings. Halcon’s purchasing these systems enhanced their ability to drive down cost.
Hydrozonix supplies, as part of their offer, an ongoing operation and maintenance program for their fully automated system. All the operating components of this oxidation systems are inspected weekly and maintained by fully trained personnel. The weekly inspections also include water-quality testing to verify performance.
The initial produced-water recycling system was designed for 40,000 barrels per day (BPD). Halcon is installing a total of five 40,000 BPD systems with the combination of dual-use HYDRO3CIDE and Hydro-Air at five locations across Halcon’s acreage. The final part of the HZO Trio program is on-the-fly disinfection.
On-the-fly disinfection is the final polish to the produced water just prior to reuse. It also provides disinfection of the blended brackish or fresh water used in the completion fluid. It is not unusual for water-transfer lines or pumps or especially working tanks to have residual bacteria contamination. So, even with an effective produced-water treatment/recycling program, dirty working tanks, contaminated pumps or lay-flat hose can reintroduce bacteria into treated/disinfected produced water.
On-the-fly disinfection prevents upsets in a produced-water handling system from creating bacterial problems in the completion fluid. Hydrozonix again utilizes ozone in its on-the-fly method, which means its effective bacteria and iron control improves compatibility. The on-the-fly system is a portable trailer that travels with the frac crew from location to location.
FRICTION REDUCERS AND OZONE
A yearlong study comparing ozone, chlorine dioxide and a third biocide all being utilized on the fly was conducted in 2012/2013 to evaluate the interference of these on-the-fly systems with friction reducers. Routinely, friction-loop tests have shown ozone improves friction reduction by as much as 20 percent. What these friction-loop tests don’t consider is the impact of friction-reducer oxidation by the oxidizer over time. Ozone has been selected because of its short half-life, meaning it degrades before it can interact with friction reducers or other frac chemicals in the blender. Other oxidizers with longer half-lifes will be available to interact with friction reducers and chemical additives introduced in the blender.
This study evaluates one operator using three different methods with the same completion fluid and technique, in this case, slickwater. The concentration of friction reducer was downloaded from FracFocus and tabulated. The improved friction reduction of ozone combined with the improved compatibility when compared to other oxidizers resulted in a significant difference. These results showed more than a 40-percent reduction in the amount of friction reducer used.
Some operators add a friction reducer at a constant dose rate. If a constant dose rate was applied, there would be no reported difference in friction-reducer use. The operator in this study adjusted the friction-reducer dose rate based on pressure readings, not on a constant dose rate. With this method, friction-reducer use can be minimized, but compatibility issues become much more apparent.
The HZO Trio program of HYDRO3CIDE, Hydro-Air and on-the-fly disinfection provides a low-cost option for your produced-water recycling program, driving your produced-water recycling cost lower than even disposal. Halcon’s purchase of HYDRO3CIDE and Hydro-Air provides them with a much lower produced-water recycling program, helping them achieve their goal of increasing produced-water utilization while reducing overall cost.
Authored by Mark Patton
Mark Patton is president of Hydrozonix. He has more than 25 years’ experience in the development, design, implementation and operation of treatment technologies. Mr. Patton’s oil and gas background includes treatment systems for waters, wastewaters, drilling muds, tank bottoms and process residuals. He holds one produced-water patent with two additional patents pending.
Mr. Patton earned his B.S. in chemical engineering from the University of Southern California in 1985.