When completing a single well, a significant amount of idle time is imposed on these costly resources. Time spent waiting for an isolation plug to be set, to position and fire perforator guns in the next zone, to retract the wireline and the perforator gun carriers, and to isolate the lubricator from the well—all of these operations contribute to a costly underutilization of the frac crew and equipment.
The equipment and technicians required to hydraulically fracture (frac) a well are expensive—estimates range up to as much as 30% of the total cost of the well.
A frac manifold is an arrangement of flow fittings and valves installed downstream of the frac pump output header and upstream of each frac tree being served by it. From the main supply line of the frac manifold, a dedicated frac supply line is installed to the goat head atop each well. Utilizing this arrangement, the manifold is used to quickly isolate wells that have completed a frac cycle and for which intervention (plug and perforate) is now required, and to redirect the flow of frac fluid to a well that is prepared for the next frac cycle. The use of actuated valves improves transition speed and eliminates the need for manual adjustment, reducing safety risk.
The use of a frac manifold in this manner is called “zipper” or “zip” fracturing, and it can provide for almost continuous utilization of the frac crew and equipment, from the first treatment at the toe of the first well to the last treatment at the heel of the last well. This represents a substantial improvement to the effective use of the fracturing resources and, thus, to the overall economics of the well.
Frac Manifold Designs
Frac manifolds can be constructed and installed to accommodate as many wells as required, in essentially any configuration. The primary variables are frac pump service capacity, nominal size of the frac lines, nominal bore size of the frac tree, and wellbore characteristics.
Typical components of a frac manifold include spools, tees, crosses, gate valves, and goat heads. These are assembled into various configurations to suit the number and spacing of wells being simultaneously serviced, the planned arrangement of the frac lines, the extent to which actuation is desired, etc. Our frac manifolds may also be equipped with a safety ladder and platform to provide safe access to the valves.
Our frac manifold design is modular, flexible, and can result in a vast array of possible configurations. Each leg of the manifold may be aligned vertically, horizontally, or at any angle, and will typically have one or two gate valves—two is common. One of the gate valves in each run may be actuated to allow for remote and fast control of the manifold with a central control panel, while a second, typically manual valve, may be used as a backup if required.
Design features and benefits
1.Enhances safety of operations: streamlined manifold design reduces clutter at well pad. Hydraulic actuated gate valves allow remote operation, removing the opportunity for personnel exposure to potentially pressurized vessels.
2.Increases number of fracs performed per day: allows for continuous operation of multiple wells, improving utilization of pumping services
3.Provides ease of operation: hydraulic valves allow remote control of manifold valves to direct flow as desired
4.Decreases number of rig up/rig down cycles: manifold design allows for control of fluid flow to multiple wells; eliminating the need for rigup and rigdown between frac stages
5.Decreases pumping downtime: allows for frac to occur at one well while running wireline services at another well simultaneously
6.Reduces multiple frac lines: single inlet for pumping equipment drastically reduces number of flowlines required
Product specifications
1.Maximum working pressure: 15,000 psi;
2.Maximum temperature rating (API): P+U;
3.Product specification level: PSL-1, -2, -3;
4.Nominal bore size: 71/16 in, 51/8 in, 41/16in;
5.Well configurations: 2, 3.
Monoline Technology
The Monoline technology delivers a number of significant improvements:
1.It is cost effective compared to the alternative traditional use of frac iron;
2.It is assembled quickly, reducing OPEX and NPT;
3.It significantly de-clutters the work environment;
4.It uses industry standard flanges with conventional tools and known recommended torque values—no sledge hammers involved. No potential for impact damage.
Frac Valves
Frac service is just about as harsh as it gets. With the introduction of “zip” fracturing, gate valves assembled into frac manifolds are exposed to nearly continuous service, flowing and controlling high-pressure, highvolume, abrasive fracturing fluid for days, and even weeks, on end.
Special features：
1.Trimmed for maximum corrosion and erosion protection
2.CRA inlay in seat pockets and ring grooves for added protection
3.“Zero-chamfer” flowbores are another standard feature, utilized in order to mitigate turbulence that is known to exaggerate erosion
4.Two grease fitting ports are utilized for flushing and greasing the valve body cavity
CASE STUDY： Frac Manifold
Background
With the combination of horizontal drilling and hydraulic fracturing technologies, shale play drilling and production has taken our industry by storm. The high cost of the frac crew and equipment, however, has a substantial impact on profitability. Failure to fully utilize the time this equipment is onsite is extremely costly.
Challenge
A major operator working in northeast British Columbia challenged Cameron to find a way to better utilize expensive stimulation resources and to increase the number of frac intervals conducted each day. Using the known conventional practices at the time they had been able to average 2 × 200 ton fracs per day.
Solution
The frac manifold design allows for essentially continuous utilization of the frac crew. This is accomplished by pre-connecting manifold outlets to multiple frac tree goat heads and directing the output of the manifold to alternating wells as isolation plugs are set and new frac zones are perforated.
Results
The daily frac completion rate has risen up to ~4 × 200 ton fracs per day, and transition time between frac stages has been minimized.
The manifold design is highly modular, and can be easily adapted to virtually any well pad layout. Quick changeout of valves and components allows for off-line repairs. Manifolds are skid mounted complete with platforms and handrails for easy transport and improved safety.
Overall, the Cameron frac manifold has been an operational and an economic success. Equipment performance related to wear or erosion has been outstanding, with as many as 1,500 frac cycles conducted with only minimal wear.
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