DE60109894T2 - SYSTEM AND METHOD FOR LIQUID FLOW OPTIMIZATION IN A GAS LIFTING OIL BORE - Google Patents

Abstract

A controllable gas-lift well having controllable gas-lift valves and sensors for detecting flow regime is provided. The well uses the tubing and casing to communicate with and power the controllable valve from the surface. Ferromagnetic chokes at the surface and downhole electrically isolate the tubing from the casing. A high band-width, adaptable spread spectrum communication system is used to communicate between the controllable valve and the surface. Sensors, such as pressure, temperature, and acoustic sensors, may be provided downhole to more accurately assess downhole conditions and in particular, flow regime. Operating conditions, such as gas injection rate, back pressure on tubing and position of downhole controllable valves are varied depending on flow regime, downhole conditions, oil production, gas usage and availability, to optimize production. An Artificial Neural Network (ANN) is trained to detect Taylor flow regime using downhole acoustic sensors, plus other sensors as desired. The detection and control system and method thereof is useful in many applications involving multi-phase flow in a conduit.

Description

BACKGROUND THE INVENTION

The The invention relates to a system and a method for optimization a fluid flow in a pipe and in particular a flow in a gas lift shaft.

DESCRIPTION OF THE PRIOR ART

Gas lift shafts will be used since the 1800s and have proven to be especially useful for increasing effective oil production rates proven where the natural Buoyancy of the deposit not enough; see Brown, Connolizo and Robertson, West Texas Oil Lifting Short Course, and H.W. Winkler, "Misunderstood or Overlooked Gas Lift Design and Equipment considerations, SPE, p. 351 (1994) is in a gas lift oil shaft in the oil field funded Compressed natural gas and into the annular space between the lining and the piping and blown out of the lining into the casing directed to a "lift" (lift) to the fluid column to provide the tubing, allowing oil out of the tubing promoted becomes. Although the piping for the blowing of the lift gas can be used, and the annular space to promote of the oil can be used, this is rarely done in practice. Originally the gas lift shafts the gas is injected at the bottom of the casing, but at deep holes Of course, this requires excessive initial pressures and Processes have been developed, the gas at different depths to blow into the holes in the casing; see, for. B. the U.S. Patent No. 5,267,469.

Of the common Type of gas lift shaft uses mechanical gas lift valves from Bellows type, which are attached to the piping to prevent the flow Gas from the ring between the lining and the piping in to regulate the piping into it; see the US patent numbers 5,782,261 and 5,425,425. In a typical bellows-type gas lift valve the bellows is preset or preloaded to a certain pressure, which allows operation of the valve, which in the preloaded Print a transmission path gas from the ring into the casing. The pressure load of each valve is determined by the drilling technician dependent on from the position of the valve in the bore, the printhead, the Chimney conditions and a lot of other factors constructed.

The typical gas lift valve bellows type has a preload to Regulate the gas flow out the ring outside the piping up to the oil to promote. In such typical bellows-type gas lift valves are various Problems frequently. First, the bellows lose often their load, which causes the valve in the closed Position fails or works differently than the design goal is. Another common Error is the erosion around the valve seat and the wear of the ball shank in the valve, often causing a partial failure of the valve or at least leads to inefficient funding. As the gas flow through a gas lift valve in a steady state often not continuous is, but a degree Hammer and bouncing shows when the ball valve is in operation is on Wear of the Valve and seat usual. Failure or inefficient operation of bellows type valves leads to corresponding performance weaknesses when operating a typical gas lift shaft. In fact it became determines that the promotion of a manhole due to valve failure or poor performance in the Operation opposite the optimum by at least 5-15% is reduced.

It would be therefore a significant step forward in developing a system and process the this performance weakness conventional Overcome gas lift valves of the bellows type. Various procedures have been developed to provide controllable valves To arrange underground on the pipe string, but all such known devices typically use an electrical Cable along the tubing to feed the gas lift valves and to communicate with them. Because of the large number of failure mechanisms, which are present in such a system, it is of course in high degree undesirable and in practice difficult a cable along a tubing, either integrated with the tubing string or with a gap in the ring between the pipe and the lining, too use. Other methods of communicating within one Boreholes are disclosed in US Pat. Nos. 5,493,288; 5,576,703; 5 574,374; 5,467,083 and 5,130,706.

U.S. Patent No. 4,839,644 describes a method and system for wireless alternate communications in a lined wellbore with a tubing string. However, this system describes an underground loop antenna for coupling electromagnetic energy in a TEM waveguide mode by means of the ring between the liner and the tube. This ring antenna uses an electromagnetic A shaft coupling requiring a substantially non-conductive fluid (such as refined heavy oil) in the ring between the liner and the tube and an annular cavity and wellhead insulators. Therefore, the method and system described in U.S. Patent No. 4,839,644 is costly, has problems with the seepage of brine into the liner, and is difficult to use as a model for two-way underground communication. Other models of underground communication, such as Flush Pulse Transmission (U.S. Patent Nos. 4,648,471; 5,887,657) have shown successful communications at low transmission speeds, but are of limited use as a communication model where high transmission speeds are required or not desired to use a complex equipment for a mud pulse transmission underground. Still other underground communication methods have been tried; see US Pat. Nos. 5,467,083; 4,739,325; 4,578,675; 5,883,516; and 4,468,665 as well as permanent underground sensors and control systems: U.S. Patent Nos. 5,730,219; 5,662,165; 4,972,704; 5,941,307; 5,934,371; 5,278,758; 5,134,285; 5,001,675; 5,730,219; 5 662 165.

It It is well known that in a gas lift shaft an increase subterraneously injected compressed gas (i.e., lift gas) not linearly equal to the amount of oil produced. That means for any special hole under a special set of Operating conditions can optimize the amount of injected gas be to the maximum of oil to promote. Unfortunately is when using conventional Bellows type gas lift valves The opening pressure of the gas lift valves preset by the bellows type, and the main control of the hole is done by the amount of gas that is blown in at the surface becomes. Feedback, for optimal promotion It can take many hours and even days to drill.

It is also well known that in two-phase flow regimes - as in a gas lift shaft - several flow regime with varying performance exist; See A. van der Spek and A. Thomas, "Neural Net Identification of Flow Regime Using Spectra Volume of Flow Generated Sound ", SPE 50640, October 1998. During it is known desirable is in a special flow regime too work, it was largely considered impossible to do so.

It would be therefore a significant advance in the operation of gas lift shafts, though an alternative to the conventional ones Valves of the bellows type are available would, especially when sensors for determining flow characteristics in the hole with controllable gas lift valves and controls the surface could work, around a fluid flow to optimize in a gas lift shaft.

The method and the system according to the preamble of claims 1 and 15 are known from the European patent EP 0721053 known. In the known method and system, a sensor mounted below a gas lift valve senses the characteristics of a generally single-phase flow of crude below a gas lift sparger whose characteristics are used to control the opening of the valves to inject an optimum amount of lift gas to reduce the density of the crude oil and the lift gas mixture generated at and above the lift gas sparging point.

The U.S. Patent 5,353,627 discloses a method for detecting a flow regime in a multiphase fluid flow by means of a passive acoustic detector. U.S. Patent 6,012 015 discloses an automatic underground flow control system with acoustic sensors and other sensors for rating Formation parameters and the inflow of water for a versatile Drilling system.

in the General would be It would be a significant step forward if you were able to do that Flow regime in a line for a two-phase flow to capture and control the operation in order to be in a desired Phase to stay.

SUMMARY THE INVENTION

The Method and system according to the invention are characterized by the characterizing features of claims 1 and 15 marked.

The problems outlined above are largely solved by the system and method of the present invention for determining a flow regime and controlling the flow characteristics to obtain a desired regime. In the preferred application, the controllable gas lift well comprises a lined wellbore with a tubing string disposed within the liner is and extends in the longitudinal direction. A controllable gas lift valve is coupled to the pipe to control gas injection between the inside and outside of the pipe, specifically between the ring between the pipe and the liner and the interior of the pipe. The controllable gas lift valve and sensors are fed and controlled by the surface to regulate such functions as the fluid communication between the ring and the interior of the tube and the amount of injected gas at the surface. Communications signals and energy are sent from the surface using the pipe and liner as conductors. The energy is preferably a low voltage alternating current around 60 Hz.

In greater detail For example, a computer on the surface of a modem with a Pipe imposed and from an underground, with the controllable Gas lift valve connected modem received communication signal. In similar In this way, the subterranean modem can provide sensor information to the system computer communicate. Furthermore, energy is fed into the pipe string and receive underground to the operation of the controllable gas lift valve to control and sen sensor sen. Preferably, the liner becomes as head of the earth return used. Alternatively, a remote grounding as electrical Recycling used become. The way for the earth return is from the controllable gas lift valve via a conductive centralizer around the pipe, which is insulated in its contact with the pipe, but in electrical contact with the liner.

In improved forms includes the controllable gas lift shaft a or more subterranean sensor (s), preferably in contact with the subterranean modem stands / stands and with the computer on the surface communicates / communicate. additionally to acoustic in many situations advantageously such Sensors like (for) Temperature, pressure, hydrophones, geophones, valve position, flow velocities and pressure difference meter used. The sensors provide measurements to the modem for a transmission to the surface or directly to a programmable interface controller for Determine the flow regime at a given position and for actuating the controllable gas lift valve and the gas blowing at the surface to the fluid flow through to control the gas lift valve.

Preferably ferromagnetic throttles are coupled to the pipe as a Series resistance for affect the flow of current to the pipe. In a preferred form an upper ferromagnetic throttle below the tube hanger to the tube is arranged around, and the current and the communication signals become transmitted below the upper ferromagnetic throttle to the pipe. A lower ferromagnetic choke is underground around the pipe arranged around, with the controllable gas lift valve with the pipe above the lower throttle is electrically coupled, although the controllable Gas lift valve below the lower ferrite throttle mechanically with can be coupled to the pipe ge. It is desirable that in operation located controllable gas lift valve mechanically below the lower ferromagnetic throttle, so that the fluid level of the Borehole lies below the throttle.

Preferably is a control unit (computer) on the surface via a master modem on the surface and the pipe with the underground slave modem of the controllable gas lift valve coupled. The computer on the surface can take measurements of one Variety of sources, such as From subterranean sensors, measurements of oil output and Measurements of the entry of compressed gas into the bore (flow and Pressure). With the help of such measurements, the computer can an optimal position of a controllable gas valve, in particular the optimum amount of injected gas from the ring inside the liner through each controllable valve into the tube, to calculate. additional Parameters can be controlled by the computer, such. B. controlling the amount at entry of compressed gas into the bore at the surface, taxes back pressure at the wells, controlling a permeable foaming or surfactant injection system to froth the oil and receiving Förderungs- and operational measurements from a variety of other shafts in the same field to the promotion to optimize the field.

The Ability, to actively monitor the current underground conditions, along with the ability the conditions on the surface and to navigate underground has many advantages in a gas lift shaft on. Lines, such. As gas lift shafts, have four broad regimes of fluid flow on, namely bubble, Taylor, surge and ring flow. The most efficient mining (oil promoted versus injected gas) regime is the Taylor flow regime.

The subsurface sensors of the present invention allow detection of a Taylor flow. The above-mentioned control mechanisms computer on the surface, controllable gas lift valves, Ga Suction, surfactant injection, etc. provide the ability to initiate and sustain a Taylor flow. In improved forms, the subterranean controllable valves may be individually actuated to obtain a localized Taylor flow.

In the preferred embodiment all gas lift valves in the bore are of the controllable type according to the present one Invention and can be controlled individually. It is desirable the oil column of one Point in the hole as close as possible on the conveyor packer to lift. This means that the lowest gas lift valve is the first one Valve in the promotion. The upper gas lift valves are used to drill the hole during the Start of the promotion initiate. In conventional Gas lift shafts These upper valves have bellows on that with a maximum allowable Error of 200 psi (≈ 13.8 bar) are preset to ensure that the valves after close the introduction. This means that the delivery pressure underground is lost to this pressure drop of 200 psi (≈ 13.8 bar) to accommodate each valve. Furthermore lick such conventional Valves often and are unable to close completely. The Use of the controllable valves of the present invention overcomes such shortcomings.

Of the Construction of such a controllable gas lift shaft is constructed that he the conventional methodology so similar in structure as possible is. This means, after lining the shaft, a packer is typically over the conveying zone set. Then the pipe string gets in communication through the lining with the conveyor zone introduced. While the pipe was stranded on the surface is constructed, a lower ferrite throttle is one of the conventional pipelines arranged to be positioned above the underground packer. In the sections of the pipe strands be where it is wanted is a gas lift valve and one or more sensor (s) with the strand coupled. In a preferred form, a side pocket mandrel becomes for picking up a slickline and pulling it out Gas lift valve or sensor used. With such a configuration may be either a controllable gas lift valve according to the present invention be used in the side pocket mandrel, or it may / may or more Sensorpaket / e be used. Alternatively, the / can controllable gas lift valve or the sensors to be transported by pipe. The pipe string becomes the surface built where again a ferromagnetic choke below the tubing hanger is arranged around the pipe string. Communication and power lines are then passed through the wellhead feed with the tubing string connected below the upper ferromagnetic throttle.

In an alternative form becomes an installation cell for sensors and communication used without the need for a controllable Gas lift valve. This means, an electronics module with pressure, temperature or acoustic sensors or other sensors, power and a modem will be in a side pocket mandrel used to work with the computer on the surface Determination of a flow regime to communicate with the help of pipe and lining conductors. alternative can such electronic modules be mounted directly on the pipe (promotion through the pipe) and be configured to pass through a pipe Wire line can be replaced. If an electronic Module or a controllable gas lift valve attached directly to the pipe is, it can only be replaced by pulling out the entire pipe string become. Measurements are communicated to the surface, and parameters on the surface (eg entry to compressed gas) are regulated to a desired one underground flow regime to obtain, with only sensors are located underground.

SUMMARY THE DRAWINGS

1 Fig. 12 is a schematic of the gas liftable manhole according to a preferred embodiment of the present invention;

2 Figure 3 is a schematic detail of a tubing string in a lined wellbore illustrating the location of a side pocket mandrel on the tubing string;

3 Fig. 13 is a series of fragmentary vertical sectional views illustrating flow patterns in a biphasic vertical (upward) flow 3A illustrates a bubble flow, 3B illustrates a surge flow, 3C illustrates a foam flow and 3D illustrates a ring flow;

4A - 4D illustrate flow patterns in a horizontal two-phase flow, wherein 4A illustrates an annular dispersed flow, 4B illustrates a stratified wave flow, 4C illustrates a surge or intermittent flow and 4D illustrates a dispersed bubble flow.

5 Figure 12 is a graph plotting compressed gas versus tube pressure and shows the four flow regimes typically encountered in a gas lift well, namely bubble, taylor, slug flow and ring flow;

6 Fig. 10 is an enlarged schematic view illustrating a controllable gas lift valve received in a wire-line-retractable side pocket mandrel;

7A - 7C Figures 12 are vertical sectional views of a preferred form of controllable valve in a cage assembly;

8th Figure 3 is an enlarged vertical sectional view showing an electronic module containing sensors coupled to the tubing string separate from the controllable valve;

9 is an illustration of the corresponding wiring scheme of the controllable gas lift shaft of 1 ;

10A Figure 3 is an enlarged schematic illustration of a controllable valve permanently coupled to the tubing string;

10B Figure 3 is an enlarged vertical sectional view of a controllable gas lift valve illustrating an alternative embodiment of the controllable valve;

11 Figure 12 is a schematic diagram showing the computer on the surface in communication with the electronics of the controllable gas lift valve;

12 is a system block diagram of a system for powering and controlling the electronics; and

13 is a block diagram of a neural network with feedforward and back propagation for the analysis of acoustic data.

DESCRIPTION ILLUSTRATIVE EMBODIMENTS

1. Description of flow regimes

Without a flow regime classification It is difficult to control fluid flow rates a two-phase flow to quantify in a line. The conventional way of flow regime classification is that of a visual observation of a flow in a pipe through a human observer. Although underground video surveys available in the stores Visual observation of an underground flow is not common practice in (horizontal bore) conveyor logs, since these require a special line (optical fiber cable). About that can out underground video surveys be successful only in transparent fluids; either gas wells or holes with transparent kill fluid. In oil wells is an alternative required for visual observation to classify the flow regime.

All flow regime generate their own characteristic sounds. A trained human observer can be a flow regime classify in a pipe rather by auditory rather than visual observations. Unlike video surveys are sound log services from various wireline wire-line services Drill holes available. The traditional use of such sound logs is leakage to determine exactly in either a lining or a pipe string. additionally Among the recorded borehole sound logs is the control panel on the surface with amplifiers and speakers equipped, for an acoustic monitoring of underground sounds permit. The sound log is typically an order over the Depth of hole of a (non-calibrated) sound pressure level after the Perform the Sound signal through five various high-pass filters (sound cuts: 200 Hz, 600 Hz, 1000 Hz, 2000 Hz and 4000 Hz). In principle, the log technician might be up Basis of the auditory observation of the subterranean sounds one Flow regime classification carry out. However, this procedure is impractical: it is prone to error not be reproduced from recorded logs (the sound becomes not recorded normally on an audio tape) and trusts the experience of the special technician.

The successful application of flow-regime classifications from tone logs in the neural network field brings some benefits to the business. First of all, it will be the application of the correct flow tion regime-specific hydraulic model for the task of evaluating promotion logs of two-phase flows of horizontal wells. Second, it allows for more limited compliance checking on recorded mining log data. Finally, it reduces the need for flow regime prediction using First Principles hydraulic stability criteria, thereby reducing computational burden by at least a factor of 10, resulting in shorter residence times.

"Flow regime"

• – Blasenströmung: eine Dispersion von Blasen in einem Kontinuum aus Flüssigkeit.
• – Intermittierende oder Schwallströmung: Der Blasendurchmesser nähert sich jenem des Rohres an. Die Blasen sind geschossförmig. Kleine Blasen sind in den dazwischen liegenden Flüssigkeitszylindern suspendiert.
• – Schaumströmung: Eine hoch instabile Strömung oszillierender Natur, wodurch die Flüssigkeit in der Nähe der Rohrwand kontinuierlich auf und ab pulsiert.
• – Ringströmung: Ein Film von Flüssigkeit strömt an der Rohrwand und die Gasphase strömt in der Mitte.

"A two-phase flow is the interacting flow of two phases, liquid, solid or gaseous, where the interface between the phases is affected by their motion" (Butterworth and Hewitt, 1979). Many different flow patterns can result from changing a shape of the interface between the two phases. These patterns depend on a variety of factors; z. As the phase flow velocities, the pressure and the diameter and the inclination of the flow concerned border border pipe etc. flow regimes in a vertical upward flow are in 3 illustrates, and include:

• - Bubble flow: a dispersion of bubbles in a continuum of liquid.
• Intermittent or slug flow: The bubble diameter approaches that of the tube. The bubbles are projectile. Small bubbles are suspended in the intermediate liquid cylinders.
• Foam flow: A highly unstable flow of oscillating nature, causing the liquid in the vicinity of the tube wall to pulsate continuously up and down.
• - Ring flow: A film of liquid flows on the pipe wall and the gas phase flows in the middle.

• – Blasenströmung: Die Blasen neigen dazu, in der Flüssigkeit obenauf zu schwimmen.
• – Geschichtete Strömung: Die Flüssigkeit strömt entlang des Bodens des Rohres und das Gas strömt an der Oberseite.
• – Intermittierende oder Schwallströmung: Große schaumige Schwälle von Flüssigkeit wechseln sich ab mit großen Gastaschen.
• – Ringströmung: Ein Flüssigkeitsring hängt an der Rohrwand, wobei Gas hindurch bläst. Üblicherweise ist die Schicht an der Unterseite viel dicker als die an der Oberseite.

The above flow patterns are obtained with increasing gas velocity. For gas wells one expects a ring flow over much of the pipe, while for oil wells an intermittent flow prevails in the upper part of the pipe. At the conditions of the tube inlet, there is predominantly a bubble flow, thus in the tube, as associated gas is released from oil as the pressure decreases, a transition from bubble flow to intermittent flow occurs. Flow regimes in horizontal flow are in the 4 illustrated and described below:

• - Bubble flow: The bubbles tend to float in the liquid on top.
• - Stratified flow: The liquid flows along the bottom of the tube and the gas flows at the top.
• - Intermittent or sluggish flow: Large foamy swells of liquid alternate with large gas pockets.
• - Ring flow: A liquid ring hangs on the pipe wall with gas blowing through it. Usually, the layer at the bottom is much thicker than that at the top.

Another flow regime was identified - the Taylor flow - that between the bubble and tidal flows of the 3A and 3B occurs and has the characteristics of each. In particular, as in 5 For example, Taylor flow is a highly desirable flow regime for maximizing oil output for a quantity of injected gas. Although the preferred embodiment is primarily concerned with achieving Taylor flow in a vertical oil well, the principles are also applicable to horizontal wells (US Pat. 4 ) and applicable to most biphasic flows in a conduit. The filtration rate is the ratio of the volumetric flow rate at piping conditions, Q, to the cross-section of the pipe, A, such that:

The Filtration speed is the speed that a phase would have, if it were the only phase in the tube. The gas volume fraction (GVF) is the gas filtration rate divided by the sum gas filtration and liquid filtration rates.

The gas volume fraction is pressure-dependent. It should be noted that in the flow loop experiments, the gas flow velocity is expressed under normal conditions (Nm ³ / h).

A convenient and illustrative way to represent flow regime against flow velocities is to map a flow regime on a two-dimensional plane with the gas filtration rate on the horizontal axis and the liquid filtration rate on the vertical axis for a given pipe pitch, see 3 , Theoretically, eight variables are necessary to define a flow regime in a pipe. In an angle-dependent flow mapping representation, only three variables are used. In this case, the approach is justified in that the three variables of flow mapping, ie, tube tilt angle, gas filtration rate, and liquid filtration rate, are the only variables that have changed in the course of the studies. All other variables, ie gas and liquid density and viscosity, surface tension, pipe diameter and pipe roughness, are fixed (Wu, Pots, Hollenberg, Mehrhoff, "Flow pattern transitions in two-phase gas / condensate flow at high pressures in 8" horizontal Pipe ", Proc. of the Third International Conf., on Multiphase Phase Flow, The Hague, The Netherlands, May 18-20, pp. 13-21, 1987; Oliemans, Pots, Trompe," Modeling of annular dispersed two-phase flow in vertical pipes ", J. Multiphase Flow, 12: 711-732, 1986).

A spans exemplary flow mapping three orders of magnitude, as well as the gas as well as the liquid flow rate. At 10 m / s liquid filtration rate a 4 inch pipe becomes a flow velocity of about 10,000 barrels of liquid per day, if the liquid is the only one in the Pipe flowing liquid is. Thus spanned such a flow illustration all situations that are of practical use in an oil field application are. As the gas volume fraction the ratio of the gas filtration rate to the sum of gas filtration and liquid filtration rate is, the pipelines of constant gas volume fraction appear at the flow picture as straight parallel lines with a rise of 45 degrees. The 50% GVF line is the line passing through the points (10, 10) and (0.01, 0.01). To the right of this line are higher ones Gas volume fractions on, while to the left of which the gas volume fraction decreases.

"Noise measurements"

jedes beliebige proportionale Band durch seine Mittenfrequenz definiert ist. Diese ist gegeben durchA sound rarely consists of only one frequency. Thus, to analyze it, a whole range of frequencies must be investigated. The selected frequency spectrum can be divided into contiguous bands (Pierce, 1981), so that: f u (n) = f L (n + 1) (3) and then f u (n + 1) = f L (n + 2) (4) wherein the nth band is limited by a lower frequency f _L (n) and an upper frequency f _U (n). It is said that the bands are proportional if the ratio f _U (n) / f _L (n) is the same for each band. An octave is a band for that f u = 2f L (5) that is, the upper frequency is twice the lower limit frequency of the band. In the same way, a 1/3 octave band is one where

any proportional band is defined by its center frequency. This is given by

The standard 1/3 octave split scheme (ANSI p. 1.6 - 1967 (R 1976)) uses the fact that 10 1/3 octave bands are almost a decade. Standard 1/3 octave bands are those that: f O n + 10 = 10f O (n) (8) ie 1, 10, 100, 1000, etc. are some of the standard 1/3 octave center frequencies. A graphic display of 1/3 octave band numbers against the frequency can be made. On a logarithmic scale, 1/3 octave bands are equidistant and have the same width.

Two from the recording devices used ranges of analysis are the 100 kHz and the 1 kHz range. The 100 kHz range spans the bands 20 to 49. The 1 kHz range spans the bands 1 to 28. Except The 1/3 octave spectra and octave spectra is also an alternative distribution scheme Decades used, possible. The center frequencies of two adjacent decade bands have a relationship from 10 on.

The Signal size in one Any given band is expressed as the sound pressure level. The sound pressure level (SPL) has a logarithmic scale and is measured in decibels (dB) (Kinsler et al., 1982). If p the Sound pressure is, then is:

wobei (SPL)_NEW der kombinierte Schalldruckpegel der n ursprünglichen (SPL)_n-Pegel ist. Zum Beispiel wenn (SPL)₁ = 100 dB und (SPL)₂ = 120 dB, wird ihre Summe (SPL)_SUM = 120,043 dB ≈ 117 dB.P _ref is a reference pressure that is often taken as 1 μPa in underwater acoustics. Bringing the decibel concept into a more familiar context, in air (reference pressure of 20 μPa), 0 dB is the threshold of acute hearing of a human being, while 130 dB would be the level of sound that induces acute pain. Assuming that the sound sources are all incoherent, sound pressure levels can be combined using the following formula:

where (SPL) _{NEW is} the combined sound pressure level of the n original (SPL) _n levels. For example, if (SPL) ₁ = 100 dB and (SPL) ₂ = 120 dB, their sum (SPL) becomes _SUM = 120.043 dB ≈ 117 dB.

"Neural Networks"

One artificial neural network is an information processing system that is designed is to the activity in the human brain (Caudill and Butler, 1992). It comprises a number of highly interconnected neural Processors and can be trained to present patterns within him Recognize data so that it does not have these patterns in advance seen data can recognize. The data representing a neural network presents become one of three sentences (Learning set, training set and assessment set) assigned and accordingly characterized. The training set is used to connect the network train, whereas the test set for monitoring the network performance is there. The valuation rate is the place where the Net its assumed skills for use on unseen Can use data.

Preferably, a neural network with feedforward and backpropagation as in 13 used for evaluation and classification of an acoustic sensor. The architecture of a neural network for classification problems at 1/3 octave spectra is in 13 shown. The neural network consists of three layers, an input layer of 52 input units, a 16-unit hidden layer and 4 units in the output layer, each corresponding to one of the flow regime target classes. The output units produce a scaled output, a number between 0 and 1, which can be interpreted as the probability of the occurrence of this particular flow regime controlling a particular pattern of inputs. The probability of the value of the four output units corresponds to each of the calculated probabilities after training the network. The output is considered low if its value is 0.5 or less, and high if it is above 0.5. Each sample in a record can be classified as:
Correct: the output unit corresponding to the target class has a high output, all other output units have a low output.
Wrong: the wrong output unit has a high output, all other output units (with the one corresponding to the target class) have a low output.
Unknown: two or more output units have a high output or all output units have a low output.
Forcibly correct: the output unit corresponding to the target class has the highest output regardless of its absolute value. This number will include all correct samples and some of the unknown samples.

A confusion matrix indicates how the network classifies all given regimes. At each one a sensitivity analysis is performed. This is expressed as a percentage change in error where a particular input is omitted from the training procedure. A surface computer that processes the sensor data may compare the target regimes with the outputs from the largest and second largest probabilities network, which are referred to as best and second best, respectively.

2. Description of a Gas lift shaft

Turning to the drawings, a gas lift shaft according to a preferred embodiment of the present invention is illustrated. Illustrated in the broad sense 1 a gas lift oil well 10 that is different from the surface 12 through a borehole and into an underground production zone 14 extends into it.

The production platform 20 is schematically above the surface 12 in 1 illustrated. A standard wellhead with a hanger 22 has a tube suspended therefrom and supported by it 26 on. The lining 24 is conventional, that is, it is cemented in the well during the completion of the well. Similarly, the tubing string 26 generally conventional, and includes a plurality of elongated tubular conveyor pipe sections connected by threaded couplings at each end of the pipe section. A gas inlet throttle 30 is used to control the entry of compressed gas into the annular space between the liner 24 and the tube 26 to allow. Conversely, the discharge valve allows 32 the discharge of oil and gas bubbles from the inside of the pipe 26 during the oil production.

Schematically illustrated are a computer and a power source 34 on the surface, with energy and communication feeds 36 by the pressure feed 38 in the trailer 22 to run. Upper and lower ferromagnetic chokes 40 . 42 are installed on the pipe to act as a series resistance of the current flow. The size and material of the flow restrictors 40 . 42 can be changed to vary the value of series resistance. Energy and communications from the source 34 be through the feeds 36 at a point below the upper throttle 40 in the pipe 26 brought in. That is, the area of the pipe between the upper and lower mass throttles 40 . 42 can be considered as an energy and communication path (see also 6 ). The throttles 40 . 42 are made of highly transmissive magnetic material, and are attached concentrically and externally to the tube, and are typically cured with injected epoxy and entrapped elastomer to withstand harsh handling.

How out 1 Obviously, a packer 44 underground in the lining 24 above the conveyor zone 14 and is used to isolate the production zone, but he the metallic tube 26 with the outer metallic lining 24 connects electrically. Similarly, the metallic hanger connects 22 (along with the valves, the platform and the other conveyors on the surface) above the surface 12 electrically the inner metallic tube 26 and the outer metallic lining 24 , Typically, such a configuration would not allow one electrical signal to be transmitted up and down the bore using the tube as a conductor and the liner as the other conductor. The arrangement of ferromagnetic chokes 40 . 42 however, changes the electrical properties of the metal structure of the well and provides a system and method for providing communication and energy signals up and down the well of the gas lift well.

1 illustrates the preferred use of a controllable gas lift valve 52 that works with the pipe 26 connected is. In 1 is every one on the pipe 26 attached gas lift valve a controllable gas lift valve 52 according to the present invention. In addition, there are acoustic sensors 51 along the pipe 26 arranged and communicate with the computer 34 on the surface.

Turning 2 to, so are the subterranean configuration of the controllable valve 52 as well as the electrical connections with the lining and the pipe 24 . 26 displayed. The pipe sections 26 are conventional, and where it is desired to install a gas lift valve in the pipe section, a side pocket mandrel, such. Manufactured by Weatherford or Camco. As in 2 The side pocket spines are concentric extensions of the tube section to see 26 and allow the wireline retraction and insertion of the contents of the side pocket mandrel.

In the gas lift shaft 10 Standard bow spring centralizers are used to tighten the pipe 26 inside the lining 24 to center. The insulating bow spring centralizers 60 ( 2 and 3 ) between the throttles 40 . 42 however, use PVC insulators 62 to the lining 24 from the pipe 26 electrically isolate. Other types of non-conductive centralizers may be used, such as: As the ball type, or an epoxy coated tubing. For example, a configuration with a high temperature rubber plug may be used as a centralizer. An energy and signal line bridge 64 connects the electronics within the controllable valve 52 with the pipe section 26 , as in 2 shown. A grounded centralizer 61 next to the controllable valve 52 is through a gripper with the lining 24 grounded ( 6 ). A grounding wire 66 ensures the return path from the electronics of the controllable valve 52 , and ground, as in 6 to be seen by the centralizer 61 and the gripper 63 to the lining 24 ,

The use of controllable valves 52 is considered preferred for several reasons. For example, conventional bellows valves leak 50 often when they need to be closed during production, resulting in inefficient operation of the well. In addition, conventional bellows valves 50 is designed for a tolerance of about 200 psi per valve, resulting in further power reduction.

Turning 6 and 7 to, that is the configuration of the controllable gas lift valve 52 in the arrangement within a side pocket thorn 70 illustrated in greater detail. The side pocket thorn 70 comprises in its outer Ge housing a gas inlet opening 72 in fluid communication with the annular space in the wellbore between the tube 26 and the lining 24 , The controllable valve 52 measures the amount of gas coming out of the ring through the gas outlet 74 in the pipe 26 into flows.

The 7A to 7C illustrate the preferred embodiment of the controllable valve 52 of the present invention. as in 7C shown is the controllable valve 52 in the side pocket thorn 70 slidably received. A gas inlet opening 72 is in fluid communication with the annular space in the wellbore between the tube 26 and the lining 24 , The controllable valve 52 measures the amount of gas coming out of the ring through the gas outlet 74 in the pipe 26 into flows.

In more detail, as in 7A is shown in the housing 80 an electronic module 82 arranged. A check valve 94 prevents backflow from the pipe through the outlet opening 74 , A stepper motor 84 turns a pinion 202 , which by a worm gear the cage 206 raises and lowers. The cage 206 stands with a seat 208 engaged the flow in the opening 210 regulated in it. As in more detail in 7B shown is a shoulder 212 Designed to fit with a matching cantilever to the cage 206 complementary to be engaged when the valve is closed. This "cage" valve configuration will be understood by a fluid engineer as opposed to the alternative embodiment with a needle valve configuration of FIG 10B considered as preferred construction. That is, a fluid flow from the inlet port 72 behind the cage / seat connection ( 206 / 208 ) allows precise fluid control without excessive fluid wear at the mechanical interfaces.

Turning 8th to, so is a modified version of the controllable valve 52 of the present invention, and is consistent with the side pocket mandrel configuration of 6 to compare. In 8th includes the tube 26 a ring-shaped enlarged pocket 100 containing the electronics and the controllable gas lift valve 52 harbors the present invention. That is, the gas lift valve 52 is mounted in the tube and can not through a slickline through the side pocket mandrel 70 from 6 used and withdrawn (ie transport through the pipe). The controllable valve 52 in 8th includes a grounding wire 102 (similar to the ground wire 66 from 6 ), which is an insulated bushing with the lining 24 grounded centralizer bow 61 connect to. The electronics module 106 is for communication and energy via the power and signal line bridge 104 with the pipe 26 connected. A motor operated cage valve 108 is illustrated schematically, but operates in a similar way as 7 to effectively communicate the annular space between the pipe 26 and the lining 24 in the interior of the pipe 26 to steer into it. Similar to in 7 is a reverse flow valve 110 intended.

8th also illustrates the provision of a variety of sensors that may be used to the gas lift shaft 10 to control. That is, an acoustic sensor 113 is on the pipe 26 mounted to detect the internal acoustic signature of the fluid flow, while similarly a temperature sensor 114 the temperature of the fluid within the tube 26 certainly. How out 8th As can be seen, the acoustic and temperature sensors 113 . 114 with the electronics module 106 coupled and electrically connected to receive energy and communication.

Similarly, a salinity sensor 116 , a pressure sensor 112 and a differential pressure sensor 118 with the electronics module 106 connected. As you can see, the salinity sensor 116 effective through the bag 100 arranged to reduce the salinity of the fluid in the ring between the lining 24 and the tube 26 capture. The differential pressure sensor 118 provides a measurement of the pressure on each side of the needle valve 108 , It can be seen that through 6 and 8th Illustrated alternative configurations include any number of sensors 112 . 114 . 116 or 118 include or exclude. Alternative sensors, such. As measuring instruments for an absolute or a differential pressure, a lift gas flow velocity, acoustic waves of a pipe, a gas lift valve position or any analog signal can be used. Similarly, the electronics module 106 and the sensors 112 . 114 . 116 packed together and independent of the controllable valve 52 be used. In the preferred embodiment, at least one acoustic sensor is used.

Turning 9 To, so should the appropriate wiring scheme of 9 With 1 be compared. As can be seen, includes the computer and power source 34 an AC power source 120 and a communication master modem 122 that between the lining 24 and the tube 26 electrically connected. 9 illustrates two separate underground communication and electronic modules that are identical, as illustrated. It should be appreciated that any such electronic module, e.g. B. in a side pocket mandrel 70 is mounted, different components and combinations, such. B. the sensors 112 - 116 or the controllable valve 52 , contain or omit. In 9 is such an electronics module (like the electronics module 82 from 7 ) between the pipe 26 and the lining 24 electrically connected. Such an electronic module 82 includes a power transformer 124 , as shown. Similarly, a data transformer 128 with a slave modem 130 coupled, as shown.

10 shows a mounted on the mandrel controllable gas lift valve 134 that is not interchangeable with a slickline. In fact, many gas lift valves in use today are mechanical lift type gas lift valves that are not interchangeable with a slickline. These mechanical valves are replaced by pulling out the pipe string. 10 shows the electronics of the mounted in the valve body controllable valve 132 it being understood that power and control are separate in the mandrel conveyed through the pipe 132 configured and mounted. 10 shows the needle valve configuration of the alternative embodiment, recognizing that the cage valve of 7 and other valve configurations may alternatively be used. As in 10 shown, a ground wire couples 136 a in the housing of the valve 132 integrated electronic module 138 and ground to the bow spring centralizer 61 , An energy and signal line bridge is in the mandrel 134 Integrates and couples the electronics module 138 with the pipe 26 , The stepper motor 142 , the needle valve 144 and the check valve 146 are in operation and configuration similar to those in 7 pictured controllable valve 52 , In a similar way to 8th are an inlet opening 148 and an outlet opening 150 provided to a fluid communication path between the ring and the interior of the tube 26 provide.

11 illustrates a block diagram of the communication system 152 according to a preferred embodiment of the present invention. 11 should with 1 and 6 are compared and contrasted, and in a broad sense encompasses a master modem 122 and an AC power source 120 , A computer 154 is with the master modem 122 shown coupled, preferably via an RS232 bus, the computer 154 an operating system, such as Windows NT, and a variety of user applications. The AC power source 120 includes a 120V AC input 156 , Dimensions 158 , and a central conductor 160 as illustrated. A fuse 162 (eg, 7.5 amps) with a transformer power 164 at about 6 volts AC and 60 Hz is shown. The power source 120 and the master modem 122 are with the lining and the pipe 24 . 26 connected, as in 11 shown schematically.

The electronics module 82 includes a power supply 166 and an analog-to-digital conversion module 168 , A programmable interface controller 170 is with the slave modem 130 shown coupled (see 9 ). On / Off decoupling 172 are provided.

12 extends the picture into 11 and shows in detail a preferred embodiment of the electronic module 82 , Amplifiers and signal processing equipment 180 are provided to the inputs of a variety of sensors 112 - 118 (please refer 8th , such as As an acoustic signature, pipe temperature, ring temperature, line pressure, ring pressure, lift gas flow rate, valve position, salinity, differential pressure, etc.) to receive. Preferably, low noise operational amplifiers are configured with non-inverting single inputs (eg, Linear Technology LT1369). All amplifiers 180 are designed with amplifier elements to convert the operating range of the individual sensor inputs into a sensible analogue output. The programmable interface controller 110 , which uses standard analog-to-digital conversion techniques, generates an 8-bit digital signal corresponding to an output of an amplifier kers 180 equivalent.

In greater detail, pressure sensors 112 (eg, produced by Measurement Specialties, Inc.) used to control the pressure in the pipe to the inner installation cell housing and differentially via the gas lift valve, as in 8th at 112 and 118 shown to measure. In economic operation, the internal installation cell pressure is considered unnecessary, but is available as an option. Such pressure transducer 112 . 118 are in an installation cell to withstand the strong vibration associated with gaslift tubing. The temperature sensor 114 (eg from Analog Devices, Inc. LM-34) is used to measure the temperature in the tube and optionally in a diagnostic mode in the housing installation cell, the current transformer, or the power supply. The temperature converters are rated for -50 to 300 ° F and are provided by an input circuit 180 adjusted to +5 to 255 ° F.

Addressing Switch 182 are provided to a special device from the master modem 122 to address. As in 12 4 address bits are switch selectable to form the upper 4 bits of a full 8 bit address. The lower 4 bits are included and used to identify the individual elements within each electronic module 82 to address. Thus, using this illustrated configuration, 1024 modules are a single master modem 122 ( 9 assigned to a single communication line. As configured, you can have up to 4 master modems 122 be housed on a single communication line.

The programmable interface controller 170 from 12 (PIC 16C77, manufactured by Microchip) has a base clock frequency of 20 MHz, and is equipped with 8 analog / digital inputs as in 184 shown, and 4 address inputs as at 186 shown configured. The PIC 170 includes a serial TTL communications UART188, as well as a controller interface 190 for a stepper motor.

The energy supply 166 from 12 converts a nominal 6 V AC line current 192 in 5V, at 194 in minus 5 volts DC and at 196 in plus 6 V DC around, by different elements within the electronics module 82 be used. The PIC 170 uses the plus 5V dc while the slave modem is on 130 the plus 5 and the minus 5 DC used (as in 192 . 194 shown). The stepper motor 84 uses the plus 6 volts DC, as at 196 shown. The power supply 166 includes a step-up transformer to convert the nominal 6V AC to 7.5V AC. The 7.5V AC is then rectified in a Graetz circuit to produce 9.7V unregulated DC. Three-port controllers provide the regulated outputs 192 - 196 which are heavily filtered and protected by an EMF trap. As can be seen, the modem is 130 the most important power consumer and typically uses 350+ milliamps at plus / minus 5 volts DC when transmitting.

In more detail, there is the digital spread spectrum modem 130 from an IC / SS Power Line Carrier chipset (ICS1001, ICS1002 and ICS1003 from National Semiconductors) and handles data transfer rates of 300-3200 baud at carrier frequencies in the range of 14kHz to 76kHz (US Patent No. 5,488,593 to U.S. Patent No. 5,478,593) Chip set in more detail and is hereby incorporated by reference).

The PIC 170 controls the operation of the stepper motor 84 by a stepper motor controller 200 (eg Motorola SA1042 step motor drive circuit). The control 200 only needs directional information and simple step pulses from the PIC 170 to the stepper motor 84 head for. A single "set" of the controller 200 At initial conditions, all elements for initial operation will set in known states. The stepper motor 84 (preferably a MicroMo gear head) places a cage valve as the main operating component of the controllable gas lift valve in the direction of its seat or away (see 7 ) at. The stepper motor 84 delivers a torque of 0.4 ounces x square inches (≈ 0.0028 Nm) and rotates at up to 1000 pulses per second (for emergency shutdowns). One complete revolution of the stepper motor 84 consists of 24 individual steps. The output of the stepper motor 84 is directly coupled to a 989: 1 gearhead, which generates the required torque to open and close the cage valve. The continuous torque required to open and close the cage valve is 3 inches-pounds, with 15 inches-pounds being required to set up or set down the cage valve.

The PIC 170 communicates through the digital spread spectrum modem 130 with the outside world via the net 202 that the modem with the lining and the pipe 24 . 26 couples, as in 9 shown. The PIC 170 uses the MODBUS 584/985 PLC protocol. The protocol is ASCII-encoded for transmission.

BUSINESS

One greater Percentage of artificial elevated oil production Nowadays gaslifting is used to bring the reservoir oil to the surface. In such gas lift shafts is compressed gas underground outside the pipe, usually in the ring between the lining and the tube blow, and mechanical gas lift valves allow a connection of the gas in the pipe section and the rising of the fluid column inside of the pipe to the surface. Such mechanical gas lift valves are typically mechanical Bellows-type devices that open and close when the fluid pressure exceeds the preload in the bellows section. Unfortunately However, a leak in the bellows is common, and this leaves the valves of the bellows type mostly inoperable as soon as the bellows pressure deviates from its preload setting, unless the bellows is complete failed, z. B. by a break. Furthermore, in such valves bellows type erosion and wear of a ball valve against Seat a usual Source for a failure, as the ball and the seat during normal operation in the often brine-like high temperature and pressure conditions often come into contact with the ball valve. Such leaks and failure are on the surface not easy to recognize and reduce the delivery capacity in the Magnitude of 15 percent due to lower conveyor speeds and higher demand on lift gas compression systems in the field.

The controllable gas lift shaft 10 The present invention has a number of data-monitoring installation cells and controllable gas lift valves 52 on the pipe string 26 on, with the number and type of each installation cell and the controllable valves 52 from the requirements of the individual shaft 10 is dependent. Preferably, at least one acoustic sensor is used to establish a flow regime using the trained artificial neural network of 13 to determine. Each of the data-monitoring installation cells and controllable valves 52 is addressable via wireless spread spectrum communication through the pipe and liner. That is, a master spread spectrum modem on the surface and an associated controller communicate with a number of slave modems. The data monitoring installation cells report such measurements as subterranean pipe pressures and lining temperatures, lift gas flow rates, gas valve position, and acoustic data (see 8th , Sensors 112 . 113 . 114 . 116 . 118 ). Such data is similarly communicated to the surface through a slave spread spectrum modem communicating through the tube and liner.

The computer 34 at the surface (either local or central) continuously combines and analyzes the subterranean data as well as the surface data to calculate a real-time pipe pressure profile. An optimal gas flow rate for each controllable gas lift valve 52 is calculated from this data. Preferably, pressure measurements are made at positions that are unaffected by gas lift injection turbulence. Acoustic sensors 113 (Sounds less than about 20 kilohertz) listen for tube-bubble patterns. The data is sent via the slave modem directly to the control unit on the surface. Alternatively, the data may be sent to a data monitoring installation cell at the hole center and forwarded to the computer. The tube bladder patterns are derived from the artificial neural network of 13 analyzed to determine the flow condition. If it is not a Taylor flow, the feed control is modified.

The is called, additionally for controlling the flow velocity The drilling can be the promotion of such be controlled to be in or near the Taylor fluid flow condition is working. Unwanted conditions such as "upsetting" or "slug flow" can be avoided become. By changing the bore operating conditions, it is possible to use a Taylor flow, the the most wanted flow regime is to get and maintain. By being able to do such undesirable Bubble flow conditions fast Underground, the promotion can be controlled so that such undesirable Conditions are avoided. That is, a quick capture such conditions and a quick response by the computer on the surface such factors as the position of a controllable gas lift valve, the Gaseinblasgeschwindigkeit, the back pressure on the pipe at the Wellhead, and even stop the injection of surfactants.

Claims (18)

A method of controlling fluid flow in a conduit, wherein the fluid is multiphase, comprising the steps of: determining the signature of the fluid flow along a portion of the conduit; Transmitting the signature to a control unit via the line; and determining the flow regime of the fluid in the portion based on the signature; characterized in that the signature is the acoustic signature of the multiphase fluid flow, and the amount of at least one of the fluids in the conduit is adjusted based on the determined flow regimen to obtain a desired flow regime. The method of claim 1, wherein the conduit an oil well forms and the multiphase fluid is the blowing of lift gas in the Shaft and the oil includes. Method according to Claim 2, in which the control unit a computer with an artificial one neural network that is trained to be a flow regime based on the acoustic signature. The method of claim 1, wherein the desired flow regime a Taylor flow includes. The method of claim 2, wherein the desired flow regime includes minimizing the amount of lift gas and maximizing the amount of oil delivered becomes. The method of claim 2, further comprising the steps of mounting one or more sensors near a production tubing (10). 26 ) in the oil well; Detecting the signature of the flow in the delivery pipe ( 26 ); Communicating the signature with the help of the conveying pipe ( 26 ) to a control unit ( 34 ) on the surface; characterized in that the sensors include acoustic sensors ( 51 . 113 ) for detecting the acoustic signature of a biphasic flow; the flow regime of the two-phase flow by means of the control unit ( 34 ) is determined on the surface; and the operating parameters of the oil well ( 10 ) on the basis of the determination of the flow regime by the control unit ( 34 ) are controlled on the surface. The method of claim 6, wherein the step of controlling comprises regulating the amount of compressed lift gas entering the oil gallery ( 10 ) is fed. The method of claim 6, wherein the step of controlling comprises regulating the amount of compressed lift gas entering the production tubing (10). 26 ) is fed through an underground controllable valve ( 52 ). The method of claim 6, wherein the step determining entering the acoustic signature into an artificial one neural network. The method of claim 6, wherein the step controlling comprises setting the operating parameters in such a way be that a Taylor flow regime is obtained. The method of claim 6, wherein additional physical fluid properties are detected. Method according to claim 11, in which the pressure and the temperature of the fluid in the delivery pipe ( 26 ) are detected. Method according to Claim 6, in which the conveying tube ( 26 ) includes a tube extending laterally from a generally vertical oil well. Method according to claim 6, comprising the step of feeding an acoustic sensor by means of the conveying tube ( 26 ). Gas lift oil well with: a pipe ( 26 ) for conveying a two-phase fluid comprising oil and lift gas to the surface; one or more underground sensor (s) ( 51 . 113 ) near the pipe ( 26 ) effective to detect a physical fluid parameter; one with the pipe ( 26 ) operatively coupled modem for receiving data from the sensor and transmitting the data to the pipe ( 26 ) to the surface; a control unit on the surface for receiving the data and determining a fluid flow regime in the pipe ( 26 ); and a throttle ( 30 ) and / or an underground controllable valve ( 51 . 113 ) for controlling the pipe ( 26 ) introduced amount of lift gas; characterized in that the throttle ( 30 ) and / or the underground valve ( 52 ) by the control unit ( 34 ) is controlled on the surface based on the determined flow regime of the biphasic fluid. Shaft according to claim 15, wherein the sensor comprises an acoustic sensor ( 51 . 113 ). The well of claim 16, wherein the computer comprises an artificial neural network for determining a flow regime based on the measurements from the acoustic sensor (10). 51 . 113 ). Shaft according to claim 15, with one with the pipe ( 26 ) coupled energy source ( 34 ) to transfer energy to the sensor ( 51 . 113 ) to deliver.