CA2230765A1

CA2230765A1 - Wellhead separation system

Info

Publication number: CA2230765A1
Application number: CA002230765A
Authority: CA
Inventors: Craig Nykyforuk
Original assignee: Individual
Current assignee: Individual
Priority date: 1998-03-02
Filing date: 1998-03-02
Publication date: 1999-09-02

Description

TEM File No. 196.1 TITLE: WELLHEAD SEPARATION SYSTEM
FIELD OF THE INVENTION
The present invention relates to a system for separating liquid from gas down stream of a gas wellhead.
BACKGROUND OF THE INVENTION
When a gas well produces natural gas, it also produces water, which may contain some mud and sediment. This water must be removed from the gas stream before it enters a pipeline system because the water could impede the flow of gas. Water in the presence of gas forms hydrates or ice which can block the flow of gas, particularly in cold climates.
This blockage can also create a safety problem in operating the well or pipeline system.
Traditionally well operators have installed separator packages which use a separator that is a minimum 12 inches in diameter and 5 feet tall. These prior art separators are very large, bulky and heavy, and are housed in buildings for access by maintenance personnel. The separators are also expensive, with units generally ranging in cost between ten and twenty thousand dollars (CAD), for instance. For shallow gas wells, this cost to separate water makes the wells uneconomic to operate, and so the wells are often abandoned.
What is desired therefore is a novel system and apparatus which overcomes the limitations and problems of prior art separators. Preferably it should provide a fairly simple and compact system with a minimum of moving parts for efficiently and automatically removing water from a gas stream. The system should be fully self contained and be light weight to avoid special supports for mounting on a gas pipeline or adjacent a wellhead, and should be relatively inexpensive for economical production of shallow gas wells and the like, particularly in cold climates.
SUMMARY OF THE INVENTION
Conventional separator theory is that the efficiency of separation between liquid and gas is based on the disengaging area. Though may be true, this theory becomes uneconomic for wells at lower flow rates. Efficiency of separation may also be effected by change in direction or change in velocity of the gas/liquid mixture. The separator of the present system is based on the view that for lower flow rates of gas, efficient separation should be achieved by combining the change in direction of the gas and its change in velocity, thus providing a more efficient, compact and less expensive design than prior art separators.
DESCRIPTION OF THE DRAWINGS
Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, wherein:
Figure 1 is a elevated front view of a wellhead separation system in an opened enclosure according to a preferred embodiment of the present invention; and, Figure 2 is an enlarged, partially transparent rear view of a separator vessel of the system of fig. l .

-2-DESCRIPTION OF A PREFERRED EMBODIMENT
The separation system of the present invention, generally designated by reference numeral 10 in fig. l, is connected on or directly adjacent to a gas wellhead.
A gas and water mixture from the wellhead enter the separation system through a two inch inlet pipe 11 which communicates with an inlet of a separator vessel 12. Referring to fig. 2 as well, the gas and water mixture first encounter a change in velocity (speed) by entering a disengaging chamber 13 which is an enlargement in the pipe 11. This is the body of the separator 12 where most of the free water separates from the gas stream and falls to the bottom of the separator. The gas continues forward and strikes an impingement baffle 14.
The impingement baffle 14 forces the gas to change direction and coalesces any water on the baffle. This water collects and by the force of gravity falls to the bottom of the separator 12. The gas makes its way around the baffle 14 and out the separator's outlet 15 and down the outlet pipeline 20, free of any water.
The water that has dropped out of the gas in the separator 12 falls and collects at the bottom of the separator. The water is first directed to the bottom of the separator by a down comer 16 whose purpose is to force any heavy particles such as sand, dirt, or silt to the bottom of the collected liquid. By forcing the water down and around the down comer, this also forces or directs any sediment to the bottom of the separator. Since sediment is heavier than water it will not rise to the top of the holding compartment 17.
The clean water then makes its way up and around the down comer 16 where it is allowed to settle in the holding compartment. This holding compartment 17 gives the water enough time for any other heavy particles or ends to drop out of the water.
Clean water is then drained off the top and discharged out of the separator.

-3-A level switch 21 is attached to a float flange 18 to control the build-up of fluids in the separator. Once a level is sensed by the level switch 21, a signal is sent to an external dump valve 22 attached to the fluid exit port 19. The valve 22 then opens to dump all fluids out of the separator through the exit port 19.
The gas exiting the separator through the outlet 15 travels through the meter run 23 where the volume of gas is measured on a chart recorder 24, which gas then exits the system at 25. The entire separator system 10 is housed within a heated insulated enclosure 26. Fuel gas is supplied from the top of the separator through a gas line and is dried in a fuel gas filter 27, which dried fuel is then burned in a heater unit 28 to heat the enclosure 26.
The separator system of the present invention is preferably, but not exclusively, is used on gas wells that are at the end of their economic life or on wells that produce relatively low volumes of gas. Good results have been achieved on shallow gas wells and low flow rates.
Some of the advantages of the present system may now be better appreciated, namely:
the system has a compact design;
is light weight relative to prior separator designs;
is simple to operate and easy to maintain due to very few moving parts;
is inexpensive to produce and install; and, the system design can be easily adapt to ASME, CSA and API codes.
The separator of the present invention is designed based on the view that the gas from the wellhead requires more space for water collection than space for water separation. The separator may be constructed from commercially available pipe fittings.

-4-The separator is designed to ASME section VIII and accepted engineering practices, and for design pressures of between 700 psig and 1480 psig at 100 °F, depending on separator model/size.
The above description is intended in an illustrative rather than a restrictive sense and variations to the specific configurations described may be apparent to skilled persons in adapting the present invention to specific applications. Such variations are intended to form part of the present invention insofar as they are within the spirit and scope of the claims below.

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