This article introduces a patent-pending, three-speed helical flow conditioner for multiphase cyclonic sand separation, detailing its design rationale, operating principles, and early field results from the Williston and Permian basins.
RYAN BOWLEY and LARS WIKSTROM, TRILOGY LLC
Sand separation equipment has long been utilized in upstream operations to manage the challenges associated with multiphase production, particularly during early production and flowback stages. However, traditional separator designs often struggle to maintain high efficiency under rapidly changing flow regimes and varying gas-liquid-solid compositions.
This article presents the design and initial field validation of a patent-pending internally conditioned three-speed multiphase cyclone design, using a dual entry helical flow insert to enhance separation efficiency and reduce pressure drop. The work draws on physical observations, engineering analysis and field results from early 2025 deployments conducted in the Williston and Permian basins.
OVERVIEW
In unconventional oil and gas plays, the first 90 days of a well’s life often generate the highest volumes of production, accompanied by highly variable ratios of oil, water, gas and solids. The fluid behavior during this period is dynamic: rates change rapidly, choke adjustments are frequent, and phase instability, including sand-laden slugging, is common. These conditions demand a high degree of adaptability from surface separation equipment.
More recent “high-efficiency” cyclonic separators, while effective at removing solids through centrifugal action, are typically designed with simplified geometries that have a peak efficiency in a small window of operational conditions. When subjected to rapidly changing well conditions, such systems can suffer from poor phase stratification, re-entrainment of solids, and inefficient solid separation.
To address these limitations, Trilogy LLC initiated the development of a new generation of Sand Separator featuring an adaptive three-speed design (Fig. 1, 1a). At the center of this system is a dual helical inlet flow conditioner, installed directly above the separation chamber. This device modifies incoming flow geometry from a simple tangential round inlet cyclone to a much more sophisticated dual helical entry with three discrete inlet configurations. This article presents the engineering rationale behind the helical flow conditioner and field results from its first deployment.
INDUSTRY SHIFT TOWARD HORIZONTAL UNCONVENTIONAL
The widespread adoption of hydraulic fracturing in horizontal wells has transformed the profile of produced fluids at the surface. In particular, tight-shale formations, such as those found in the Bakken, Permian and Eagle Ford, typically produce large volumes of frac sand and formation solids, especially in the initial days and weeks following well completion.
Unlike conventional wells, where solids production might be considered a failure mode, sand carryover is now a predictable and expected aspect of early production. Operators must contend with large quantities of entrained sand across a range of flow regimes that can transition rapidly, due to choke changes or gas-liquid ratio shifts. These evolving conditions place increased demand on surface separation equipment to be both efficient and resilient.
As a result, sand separation has shifted from an ancillary concern to a primary design criterion in early production systems.
HISTORICAL CONTEXT: THE EVOLUTION AND LIMITATIONS OF SAND SEPARATION DESIGNS
The separation of sand and solids from production fluids has long been a fundamental requirement in upstream operations. Over time, different types of equipment have been developed to achieve this objective, each with its own performance envelope and limitations. Understanding the evolution of these designs provides important context for the rationale behind flow conditioning advancements.
Traditional, conventional, three-phase horizontal separating vessels would capture the small amount of solids that a vertical oil well would produce. However, once fracing accelerated, the separators could not handle the amounts of solids that newer wells were producing.
SAND CANS AND OTHER NON-CYCLONIC EQUIPMENT
Early separation systems were known as “sand cans.” They relied on two principles: slowing fluid by expanding flow area and allowing solids to settle by gravity. Designs varied, but all used vessel volume and retention time to drop solids from suspension. Sand cans are still in use today.
Common styles included wide-spot or horizontal traps, which were simple and inexpensive, as well as vertical vessels with baffles of mixed effectiveness. Regardless of configuration, they depended on low velocities, high gas fractions and steady flow conditions rarely seen during modern flowback.
At high rates with heavy sand, re-entrainment and short-circuiting were frequent, lowering efficiency and raising downstream risk. Performance ranged widely, from as high as 80% on gas-rich wells to poor results under many other conditions.
SPHERICAL SEPARATORS
Spherical separators were introduced as a more economical option for sand separation. These systems typically used an offset tangential inlet to induce some rotational momentum thereby generating centrifugal forces. Many of these units were also outfitted with different types of baffles and diffuser plates all with the aim of improving separation. Spherical units were relatively inexpensive to make by simply taking two end caps for a traditional pressure vessel and welding them together. This design was not introduced, because the spherical shape lends itself well to cyclonic design, however, performance remained poor, because separated sand remains in the sphere and is easily re-entrained, which is a problem shared by other non-cyclonic equipment.
CYCLONIC SEPARATORS (TANGENTIAL ENTRY)
Hydro cyclones and cyclones are the gold standard in separation for most industries and applications worldwide and have been in use for over a century. Although properly designed cyclones have existed in the oil field for many applications throughout the decades, the sand removal industry did not adopt them widely until very recently. There was an industry desire to “reinvent the wheel,” only to realize that the classic cyclone is still the best device for the task.
Cyclones introduce the flow into a cylindrical body near the top (inlet) to induce a high angular velocity into the chamber powered by the inlet momentum. This spinning fluid creates a centrifugal force that drives solids outward to the vessel wall, and as the flow spirals down and around the cylinder, the solid particles hit the wall and continue to travel down a cone and out a pipe (underflow) into a collection container located below. Once in the collection chamber, they cannot be re-entrained back into the flow. The clean fluids leave the cyclone through a tube going out the top (overflow). This design has proven to be the most effective design known, with many textbooks and technical papers available to aid in the design for any application.
Not all cyclones are created equal, however, and they must be designed for an application. Cyclones are essentially centrifuges that are driven by the fluid flow, rather than a motor. Because it is the flow itself that causes the fluid to spin, the dimensions of all the components must be designed for a given scenario. Overall length, diameter, cone angle and other dimensions are important. Dwell time, viscosity and particle size are all variables accounted for in a proper design.
The inlet area is probably the most important part of a design, as it determines the velocity of the fluid entering the cyclone, as well as the shape and trajectory. Most basic oil field cyclones today are designed with a single inlet size. Some units can change this size before installation but cannot change during operation.
Since oil field cyclones are also a pressure vessel, they are limited in their design and must adhere to different engineering codes, such as API 6A and ANSI. These codes control wall thickness, nozzle placement and shape, as well as many other material and dimensional limitations. Most oil field cyclones, therefore, use a tangential circular inlet, as this is what the code allows. Often, the inlet is not aligned with the tangent of the cyclone inside, due to restrictions of the various engineering codes. A non-tangential inlet is the worst choice for a cyclone, and even a truly tangent inlet is not preferred, as the flow path of the inlet stream will impact itself as it comes around, causing substantial turbulence in the top portion of the cyclone.
In most other industries, a helical entry is used when operating at lower pressures where it is easy to create more complex shapes. Helical entries are the best design hydrodynamically, and introduce the flow into the cyclone where the least turbulence is created and where the flow is traveling in a downward helix from its entry point. Lastly, most oil field cyclones use a circular inlet driven by the pressure vessel code constraints. The fluid immediately must change its flow path shape, causing disturbances. For this reason, the preferred shape of the inlet is rectangular, Fig. 2.
Cyclones gained traction as a preferred option for sand-heavy flowback environments. However, early cyclonic systems used in oil and gas lacked the geometric features and flow optimization required to deliver high efficiency. Though at times they generate enough velocity to create good separation, the simplification of these systems meant that their actual separation performance was often underwhelming. Even under optimal conditions, they were frequently limited to around 80% efficiency. Still, performance was strongly dependent on well-controlled inlet velocities and pressure. The fixed nature of their geometry made them less adaptable to the inherently variable conditions during early well life, particularly during transitions between flow regimes.
HIGH-EFFICIENCY CYCLONES
Modern high-efficiency designs feature improved geometries, delivering greater velocity. With the increase in velocity also came an inherent and unintended increase in back-pressure. These units also lacked the ability to dynamically adapt to fluctuations in flowrate, gas-liquid ratio, or solids content. Without flow conditioning and speed control, performance degrades quickly in transitional conditions, and erosion at critical points remains a concern, particularly at the inlet and body of the cyclone.
Because these systems rely on static inlet geometries to control flow velocity, operators have no ability to adjust flow dynamics in real time. This frequently results in poor or excessive inlet velocity. When velocity exceeds optimal thresholds, erosion accelerates, especially within the cyclone body leading to rapid material degradation and, in some cases, catastrophic failure of the internal components.
DESIGN OBJECTIVES
The initial design goals were pragmatic and application-driven. The system needed to:
Maintain proper velocities under a wide range of flow conditions to improve separation efficiency.
Reduce re-entrainment of solids, especially during slug flow or choke surges.
Mitigate internal erosion caused by high-velocity sand-laden flows.
Maintain or reduce overall system pressure drop.
After multiple design iterations, a dual inlet helical insert was developed. This patent-pending insert solved the inherent issues of the tangential inlet by converting the tangential circular inlet of the pressure vessel into a helical rectangular inlet within the cyclone itself. The flow enters the insert and is rerouted into the cyclone chamber in a hydrodynamically controlled helical manner and separation begins immediately within the insert itself. Compared to tangential or radial entries, the helical profile provides smoother flow transitions and eliminates initial turbulence.
This is a significant improvement in efficiency, as the laminar flow allows solids to separate faster and for longer, meaning smaller and smaller particles make it to the wall. But the real technological advancement is the addition of the second helical inlet. Multiple inlets are common in many industrial cyclones, as the inlets become smaller and closer to the cyclone wall, reducing the separation distance for a given inlet area. Normally, multiple inlets are operated together and simply distribute the flow via multiple smaller inlets.
In Trilogy’s design, the inlets are designed to run separately or together which can only be achieved using a helical top entry inlet. If tangential inlets were used in this manner, there would be a large hole on the closed inlet in which the open inlet’s flow would have to travel across, causing massive turbulence. Since the flow is being forced towards the cylinder wall, there could not be a worse place to have an open hole. With the inlets being relocated to the roof via the insert of the cyclone, the flow can pass over the non-flowing inlet with little to no effect. The non-flowing side quickly fills with gas and creates a gas barrier, which the fluids flow underneath.
The dual helical flow conditioner allows both inlets to run individually or at the same time, Fig. 3. Because the geometry of the helical channels can be customized sizes, this gives the cyclone three unique flow areas, equating to three unique speeds, making the unit tunable on the fly. This gives the sand separator a far wider operating range with no moving parts. An additional benefit to the three speeds is the ability to control back pressure when that is a priority.
FLOW BEHAVIOR AND PHYSICAL OBSERVATIONS
The dual helical flow conditioner was designed to create a smooth, consistent swirl after the inlet and before the fluid reaches the main separation chamber. Removing the velocity controlling component from the inlet and inducing it internally made obvious improvements to long-term wear. What became evident in these early deployments was that most of the separation appeared to occur in the helical region itself. This not only helped initiate early phase separation but also improved utilization of the available volume in the cyclone body—enhancing efficiency by making better use of internal surface area and flow path stability.
PRESSURE DROP AND EROSION CONSIDERATIONS
Field pressure monitoring indicated that the helical entry path reduced pressure fluctuations during choke transitions and high-sand events. Operators reported smoother line pressure profiles and less strain on downstream pressure control equipment.
In addition, wear inspections after deployment showed minimal erosion near the inlet and along the separator base. Compared to older designs where vortex instability or jetting often caused hotspot wear, the flow-conditioned systems showed signs of improved internal velocity control.
FIELD DEPLOYMENT AND EARLY RESULTS (2025)
The first field deployments of the separator equipped with the internal helical conditioner took place in early 2025 in the Williston basin, with subsequent deployments in the Permian. Data collection focused on solids recovery, pressure differential, maintenance intervals and flow behavior.
Sand capture was consistent across applications, and operators reported a reduction in downstream carryover. After extended use, internal inspection showed minimal erosion at known wear points supporting the design goal of reducing maintenance requirements.
One of the most compelling validations of the helical flow conditioner came from a 48-hr field deployment in the Williston basin. A major operator facing significant sand management challenges partnered with Trilogy LLC to test the Sand Titan under live production conditions. The unit captured 29,447 lbs of sand at an average particle size of 140 microns, achieving an overall efficiency of 99.3% with zero downtime and no measurable wear on the downstream choke seat or stem.
Performance metrics by inlet configuration were as follows:
Inlet A (20 hrs): 7,408 lbs captured at 37.2 ft/s, 197 bbl/hr, 1.5 MMCFD, 2300 psi, Fig. 4.
Inlet B (4 hrs): 3,356 lbs captured at 55 ft/s, 308 bbl/hr, 4.4 MMCFD, 2150 psi, Fig. 5.
Combined A+B (24 hrs): 18,683 lbs captured at 38.3 ft/s, 343 bbl/hr, 6.1 MMCFD, 1950 psi, Fig. 6.
Post-run inspection of the blowdown tank connected to the test treater confirmed minimal residual sand—just 200 lbs compared to the 29,447 lbs captured—indicating exceptional effectiveness. Field crews reported that the dual-inlet configuration allowed them to adapt to fluctuation, while maintaining ease of operation. This early field success underscored the Sand Titan’s ability to eliminate downtime, protect production hardware and redefine separator performance in dynamic shale environments.
PERFORMANCE COMPARISON TO PRIOR-GENERATION DESIGNS
During early field trials (Fig. 7), the flow-conditioned separator was deployed in locations where similar operations had previously used conventional cyclonic and spherical separation units. While the test conditions were not part of a controlled side-by-side study, qualitative observations and operating metrics provide a useful basis for comparison. Notably, during all test periods, the units consistently maintained separation efficiencies above 99%, even under fluctuating flow conditions. This level of performance represents a substantial improvement over earlier generation separators, particularly during periods of high sand loading or dynamic choke adjustments.
SAND RETENTION AND CARRYOVER
Compared to earlier-generation tangential cyclones, the internally conditioned unit exhibited fewer instances of sand carryover into downstream vessels. This is particularly notable during early flowback, where increasing and decreasing pressure and frequent choke adjustments often cause temporary fluid surges. In prior deployments using static inlet cyclones, these surges frequently led to sand bypass. The more stable flow achieved through the helical conditioner appears to reduce such events by nearly eliminating initial entry turbulence.
PRESSURE BEHAVIOR
While traditional high-efficiency cyclones can often deliver strong separation performance at optimal well conditions, they can exhibit elevated pressure drop—especially at higher flowrates. In contrast, operators noted that the helical inlet maintained separation efficiency while preserving line pressure across a range of gas and liquid loading conditions. This smoother behavior was especially beneficial, when wells transitioned from water-dominant to gas-dominant production.
OPERATIONAL SIMPLICITY
The internal flow conditioner’s passive nature also offered a contrast to previous approaches that relied on operator-provided estimates of production conditions—projected flowrates, gas-liquid ratios, and sand loading—to select a fixed inlet nozzle configuration. This process involved a degree of guesswork, often resulting in suboptimal inlet sizing, once actual field conditions deviated from projections. In contrast, the internal dual helical flow conditioner removes that burden by embedding adaptive flow control directly into the vessel's geometry, and the passive design enables broad operating range adaptability with minimal operator intervention. This not only simplifies deployment but reduces the number of failure points in the system.
CONCLUSION
Internal dual helical three-speed flow conditioning represents a promising design path in cyclonic separation. The patent-pending dual helical insert described here offers a passive solution for improving separation efficiency, reducing erosion and stabilizing flow in multiphase applications. Field results from 2025 suggest tangible operational benefits, and future iterations may further improve performance through geometry optimization and automated control integration, Fig. 8. WO
RYAN BOWLEY is a Professional Mechanical Engineer and the COO of Bowley Lock Company Inc. He is a senior technical advisor at Trilogy LLC. He is the original inventor of the three-speed helical flow conditioner and led its commercial development from conceptualization through to field deployment. Ryan has contributed to the design and development of some of the most widely used high-efficiency cyclonic separators in upstream oil and gas. His expertise spans both conceptual engineering and field testing, making him a key contributor to next-generation separation technology.
LARS WIKSTROM is the CEO of Trilogy LLC and brings nearly 20 years of experience in the oil and gas industry, with a career dedicated to flowback operations and sand management. He led the development, funding, and rapid deployment of the Sand Titan system, overseeing its initial field trials and performance data analysis. Under his leadership, Trilogy has emerged as a technology-forward service provider, delivering innovative solutions that improve wellsite efficiency and equipment longevity.