Wellhead production units were developed in response to producers' requests for a completely integrated and pre-assembled package to provide heating and separating capabilities. These units consist of an indirect heater and a vertical or horizontal separator, mounted on a structural steel skid with interconnecting piping and instrumentation installed, ready for operation. The basic components are standard units; each sized and selected for the customer's needs. The components as well as the complete unit have high salvage value and can be easily adapted for other Redhead applications. In addition, a low-pressure separator can be added to the assembly to provide two-stage separation. Also, the separators can be furnished for three-phase instead of two-phase operation. The unhoused or open units are designed for moderate climates and give efficient operation at a minimum of cost. The enclosed units are designed for cold climates to give efficient operation with freedom from freeze-ups. KW International stocks standard KW International unhoused units with vertical separators in various combinations are shown. Other units are fabricated as required to customers' requirements.
Each basic component is sized individually, based upon the customer's wellstream characteristics. Indirect heaters are selected from the wide range of standard firebox sizes and coil sizes to provide sufficient heat to control the separation temperature at the optimum level. This provides fuel economy and increased liquid recovery without problems from hydrates and freeze-up. High pressure coils with working pressure up to 10,000 psig, and split coils with chokes are available.
The vertical separator is selected from the wide range of sizes and working pressures available from KW International's standard lines. This is also required when sizing the indirect heater to assure that an adequate firebox is furnished. The operating pressure of the separator is normally dictated by the gas sales line pressure. The selection of a three-phase separator versus a two-phase separator will depend upon whether or not water is expected with the production, either initially or later as the reservoir ages. Horizontal separators may be selected for the customer's application to provide a more compact assembly of high capacity.
Using all standard components provides units with field-proven performance and rugged dependability. They also provide maximum interchangeability and salvage value.
Three types of production units:
- Indirect heater and vertical separator mounted on a structural steel skid
- Indirect heater and a horizontal separator mounted on a structural steel skid. The horizontal separator may be mounted piggyback on the heater
- Indirect heater and horizontal separator integrated into an enclosure for cold weather protection. These are referred to as "Enclosed Production Units"
How it Works (standard units)
The wellstream enters the heater coil inlet and passes through the coil to the choke valve on the separator inlet. Pressure is reduced as the wellstream passes through the choke and into the separator. The separator inlet deflector forces the liquid against the separator shell and allows the gas to be released. The liquid slides along the shell and downward into the liquid accumulation section. The liquid level control in the liquid accumulation section then discharges the liquid to storage. The gas moves upward from the inlet and through the wire mesh mist extractor before leaving the separator through the top outlet connection.
A thermostat in the separator controls the heater-firing rate to maintain the wellstream at a temperature sufficiently high to prevent the formation of hydrates in the separator. The thermostat in the heater shell is set as a high temperature shutdown to prevent the water bath from overheating.
- Maximum liquid recovery as a result of operating at the lowest possible gas and liquid temperature under controlled conditions. In KW International production units, the wellstream separation temperature is controlled directly from the separator
- Unattended operation, plus easy installation and start-up, help put more profits into well production
- Instrumentation, valves, removable coils, and removable fireboxes offer easy maintenance
- Optimum-sized heater and separators provide fast start-up, effective heat transfer, and low operating costs
- KW International units incorporate several safety features such as flame arrestors, "Safe Trap" fuel gas scrubbers, ASME Code construction separators, and API 12-K specification heater flow coils. A wide variety of optional safety features are available
- Custom designed units are available to handle special applications
- Enclosed units are available upon request and designed to meet customer's specific requirements for safe and dependable cold weather operation
Standard Skid Mounted Production Unit
- 1- KW International skid mounted Water Bath Indirect Heater and Vertical Separator Production Unit, consisting of the following items:
- 1- Indirect Heater with firetube and wellstream flow coil, both removable.
- 1- Vertical, 2 phase, ASME Code constructed and stamped Separator
- 1- Oilfield type skid
- 1- Piping assembly consisting of the following items piped up for operational purposes:
- 1- Fuel gas "Safe-Trap" with high-level safety shutdown (6-5/8" dia. x 2'-0" high)
- 1- 1" Fuel gas relief valve
- 1- KW International Flame Arrestor
- 1- Fuel gas manifold with:
- 1- Low pressure strainer and drain valve
- 1- Main line fuel gas line block valve
- 2- 2" Dial face, 0-60 psig. pressure gauges w/ isolating valves.
- 1- Lot of pipe, pipefittings, copper tubing and tubing fittings for hook-up.
- 1- High efficiency burner w/pilot light
- 2- Fuel gas regulators
- 1- Instrument gas regulator
- 2- Thermostats w/ separable sockets
- 1- Diaphragm operated fuel gas control valve
- 2- 3" Dial face thermometers w/ separable sockets
- 2- Ball valves
- 1- Needle valve
- 1- 2" NPT adjustable choke
- 1- 4-1/2" Dial face 0-2000 psig. pressure gauge
- 1- 1" NPT Separator relief valve
- 1- Reflex liquid level gauge assembly
- 1- Liquid level controller
- 1- Diaphragm operated liquid dump valve
- 1- 3" Locking hatch (fill connection)
- 1- Removable stack
- Paint: One coat of standard primer and one coat of pallet tan topcoat