Source: https://patents.google.com/patent/US7086417?oq=7350717
Timestamp: 2018-06-23 08:43:12
Document Index: 709693662

Matched Legal Cases: ['art 8', 'art 9', 'art 10', 'art 12', 'art 13', 'art 14', 'art 13', 'art 14', 'art 13', 'art 12']

US7086417B2 - Gas flow control device - Google Patents
Gas flow control device Download PDF
US7086417B2
US7086417B2 US08859353 US85935397A US7086417B2 US 7086417 B2 US7086417 B2 US 7086417B2 US 08859353 US08859353 US 08859353 US 85935397 A US85935397 A US 85935397A US 7086417 B2 US7086417 B2 US 7086417B2
US08859353
US20010025651A1 (en )
Alcino Resende De Almeida
This is a Continuation of application Ser. No. 08/186,469 filed Jan. 26, 1994, now abandoned.
The present invention is directed to a gas flow control device and more specifically to a gas flow control device for use in oil wells producing by continuous gas-lift. Such a gas flow control device is sometimes referred to in the industry as a gas-lift valve having a housing and a valve seat. The latter terminology is used throughout the specification.
At wells where production is by continuous gas-lift a valve commonly used in working of the well is referred to as a gate valve. It is the valve which lets in gas from between the annulus and the production pipe, into the latter. At a given stage of well discharge production is carried out by means of this gas.
Gate valves consist mainly of a gate which is preset at a given diameter, which does not change as long as the valve is within the well. Flow of gas past this gate is highly irreversible and therefore much load is lost and also it is difficult to calculate rate of flow of gas past the valve, thereby complicating any design or examination.
This invention is of an improvement to the seat of this kind of valve, with the aid of an optimum geometric arrangement of such seat so as to render flow isoentropic within the valve, thereby greatly reducing the unsuitable effects referred to in the geometry currently adopted. This new idea consists of a so-called compact venturi which is the result of coupling a tapering nozzle to a conical diffuser. This device is almost as efficient as a regular venturi, though quite a lot shorter (a requirement as regards the valve) and much easier to make, therefore cheaper.
Use of this kind of geometry leads to a rise of about 20% in the possible rate of flow of gas through the valve for the same pressure differential between casing and pipe, or, also, a drop of 7% to 20% in casing pressure needed to withstand the same flow of gas at same pipe pressure (usually the higher of these two figures applies).
A good example of an instance of when the newly-invented valve would be needed is that of satellite wells in deep water where heavy flow and high pressure occur.
Invention will now be described in greater detail with the aid of the drawings attached hereto, where:
FIG. 1 part section view of a gate valve of the kind in current use, and FIG. 1 a shows an enlarged view of a section of seat;
FIG. 2 is a full cross-sectional view of said seat;
FIG. 3 is a view similar of FIG. 2 showing gas flowing through it; and
FIG. 4 is an enlarged cross section of the improved seat according to the present invention used in the gate valve.
FIG. 1 is a sketch of a gate valve type of gas-lift valve currently in use. In the Figure there is a point marked A where gas enters the valve, passes through the valve seat B (that is, the gate), passes check valve C and leaves out of nose D for the inside of the pipe, FIG. 1 also shows a detailed view in section of the seat, shown as a sketch in FIG. 2, in which the cylindrical body of valve 1 can be seen, the housing 2 for the seat, and the seat 3, the gate 4 and o ring 5.
It will be seen that seat 3 is just a disk in which a cylindrical hole of the wanted diameter has been drilled. Edges are, as a rule, sharp but they may also be slightly chamfered B.
FIG. 3 is a sketch of flow lines through the gate 4 as through seat 3. Sudden contracting and expanding causes swirls which bring about heavy load losses. Furthermore, the smallest area of flow does not take place along the tight part (seat) but rather, further on, as a phenomenon known as “vena contracts”.
Usual kind of modelling consists in supposing an isoentropic flow (reversible adiabatic flow) and then introducing a correction factor (discharge factor), theoretical results being compared with those arrived at experimentally. However, this discharge factor is difficult to express for it depends on several other factors, many of them intangible as regards any theoretical modelling. Hence any designing and study of continuous gas lifting becomes difficult because they depend on proper calculation of gas discharge rates through the valves. Furthermore, the irreversibilities introduce an extra load loss into the system (this is transformed unnecessarily into heat).
In order to diminish the abovementioned drawbacks this invention provides a new kind of geometry for seat 7 as shown in the enlarged sketch of the section at FIG. 4.
The improved seat 7 has a curved upper part 8, a straight intermediate vertical part 9, and a straight sloping lower part 10, with central space 11 consisting of a first sloping nozzle kind of part 12, where gas is gradually speeded up; a second cylindrical part 13 diameter of which is the same as that wanted for the gate and which represents main restriction to flow, and a third part 14 in the shape of a conical diffuser, where gas is gradually slowed down. Thus irreversibilities are diminished and the place where flow is least lies at the second part 13, the vena contracts phenomenon being thereby avoided.
Angle α which is responsible for length H1 of the third part 14 is limited by whatever length is available (this being more critical in 1½″ valves unless modifications are made to the body thereof). Diameter d1 may be the same as d2, but generally, for assembly reasons, is slightly less. Likewise, second part 13 may be reduced, theoretically, to one only part but, also for practical reasons, its length should always be h2 even though small, and h3 should be the length of the first part 12 shaped like a sloping nozzle.
This arrangement is of ten referred to in literature as a compact venturi, since it is like the ordinary venturi, but quite a lot shorter and easy to make, without however leading to any great differences in performance.
1. In an oil well having a casing with tubing concentrically disposed therein, an apparatus for controlling gas lift, said apparatus comprising a gas lift valve mounted on said tubing and having an inlet end in communication with a space between said tubing and said casing and an outlet in communication with an interior of said tubing, said gas lift valve consisting of a housing and a nozzle mounted in said housing, said nozzle having a continuously open passage through which gas is allowed to flow, wherein said passage consists of a curved inlet portion through which gas flow is speeded up, a smooth straight, intermediate portion providing a main restriction to gas flow and a smooth, outwardly tapered, conical shaped outlet portion through which said gas flow is gradually slowed down, reducing the gas pressure loss and rendering gas flow substantially isoentropic.
2. In an oil well having a casing and a tubing with an annulus defined therebetween, an apparatus for controlling the flow of gas from said annulus into said tubing, said apparatus comprising:
a divergent outlet portion through which said gas flow is gradually slowed down, thereby reducing the gas pressure loss and rendering the gas flow substantially isoentropic.
3. An oil well as in claim 2, further comprising:
a smooth straight intermediate portion located between said convergent inlet portion and said divergent outlet portion, said intermediate portion providing a main restriction to said flow.
said diffuser portion including a diffuser first end and a diffuser second end, and a diffuser flow path therebetween,
whereby pressurized gas can flow into said at least one inlet port of said gas flow control valve through said continuous flow path, and out through said at least one outlet port into a production string.
5. A gas lift system as in claim 4, further comprising a check valve downstream from said diffuser portion responsive to said flow of pressurized gas.
8. A device as in claim 7, further comprising a check valve disposed downstream from said diffuser portion and responsive to said flow of gas.
9. The device of claim 7, wherein said diffuser has a conical contour.
placing a gas lift valve within the well, at a predetermined location, said gas lift valve having an inlet end in communication with said annulus, and an outlet end in communication with an interior of said tubing;
flowing compressed gas into the annulus;
gradually slowing down said gas flow in a divergent outlet portion of the gas lift valve, thereby reducing the gas pressure loss and rendering the gas flow substantially isoentropic; and
11. A method as in claim 10, further comprising flowing gas ejected from the outlet portion through a check valve before said mixing step.
US08859353 1993-01-27 1997-05-20 Gas flow control device Expired - Lifetime US7086417B2 (en)
BRPI9300292 1993-01-27
BR9300292 1993-01-27
US18646994 true 1994-01-26 1994-01-26
US08859353 US7086417B2 (en) 1993-01-27 1997-05-20 Gas flow control device
US20010025651A1 true US20010025651A1 (en) 2001-10-04
US7086417B2 true US7086417B2 (en) 2006-08-08
ID=4055714
US08859353 Expired - Lifetime US7086417B2 (en) 1993-01-27 1997-05-20 Gas flow control device
US (1) US7086417B2 (en)
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