NO774446L - PROCEDURES AND DEVICES FOR DEGASSING A VISCUES VAE - Google Patents

Description

Method and device for degassing a viscous liquid.

The present invention relates to the treatment of drilling fluid, and more specifically a system for degassing drilling mud. The present invention provides a centrifugal pump system for pumping gas-containing drilling fluids at the same time as. the gas streams that are removed from such liquids are delimited in pipelines through which they are led to safe disposal areas. Such a centrifugal pump system desirable for transferring such gas-containing fluids to degassing or deaeration containers, or out of such containers during periods of incomplete degassing...

When drilling a well for oil, gas and the like, the drill bit is carried in the wellbore using a pipe string. The pipe string is composed of a number of interconnected single t-pipe lengths. Inside the pipe string, drilling fluid is led down to and through the drill bit. The drilling fluid at the bottom of the wellbore flows up into the annulus between the outer surface of the tubing string and the inner surface of the wellbore, up to the ground surface and then through a return pipe to storage containers on the ground surface, commonly referred to as mud tanks.

The drilling mud is usually an aqueous solution of solids which generally contains minerals such as bentonite and 'barite'. The drilling mud lubricates and cools the drill bit and acts as a carrier for collecting cuttings and rock residues from the well for disposal. The drilling mud also forms a pressure seal in the wellbore and thereby prevents gas escaping from the well. The pressure exerted by the drilling mud column is usually greater than the pressure that will be released if a gas pocket is encountered while drilling the well. The drilling mud column counteracts the gas pressure and prevents blowouts, but is very often contaminated by the gases the mud comes into contact with during the drilling operation.

In many cases it is desirable and indeed often absolutely necessary to remove the gases from the drilling mud and transfer them to a disposal area. As it is economically unfeasible to dispose of the contaminated drilling mud, and due to fa-

clean for the gases in the mud to be released into the atmosphere in large quantities, which can create dangerous conditions at the drilling site,

it is necessary to treat the mud to remove the gases and re-circulate the degassed drilling mud through the borehole. The contaminated gases can be toxic or highly explosive and the release of such gases into the atmosphere would pose an undue risk to personnel in the drilling area. The presence of gas in the drilling mud reduces the mud's weight and affects its viscosity, so that it is often unsuitable for recirculation through the borehole. When gas is present in the drilling mud that is circulated through the borehole, this increases the risk of blowout in the well.

A “Notice to Lessees and Operators of Federal Oil

and Gas Leases in the Outer Continental Shelf, Gulf of Mexico Area" was published on May 7, 1974 by the United States Department of

the Interior Geological Survey, Gulf of Mexico Area, regarding-hydrogen sulfide during drilling operations. This "Notice" sets out regulations for drilling operations under conditions where it is possible or probable that during drilling you will penetrate reservoirs that are known or assumed to contain hydrogen sulphide. Paragraph 3. f. states that "drilling mud containing H^S gas must be degassed at the optimal location for the special rig design used. The gases that are removed below must be piped to a closed flare system and burned at a suitably distant chimney."

The technique's position includes examples of systems

for degassing drilling mud, many of which use a vacuum tank and some kind of circulation arrangement that exposes the drilling mud to a vacuum environment, whereby the trapped gas can escape.

However, this is only part of the task, as serious problems are associated with the handling of drilling mud, particularly when evacuating the drilling mud from the vacuum tank for returning the degassed mud to the wellhead. Accurate control of the amount and rate at which drilling mud is introduced into the vacuum tank, degassed mud leaves the vacuum tank, and gases are evacuated from the tank is necessary to produce an acceptable product at the required flow rate.

In certain previously known systems, a . special vacuum pump which is often exposed to ingest drilling mud,

a situation that usually destroys the pump mechanism and, at the very least, makes it necessary to shut down the entire system for cleaning. There have also been problems with previously known devices

by adapting the negative pressure in the vacuum tank to the entire system's flow requirements, which can change continuously.

A number of efforts have previously been made to eliminate the use of a mud jet to produce the mud flow, e.g. attempts have been made to replace the pressure washer with a centrifugal pump. However, such previous attempts have not turned out to be entirely successful due to tendencies for air pockets in the pump when the sludge supply to the tank is insufficient, or due to swirling of sludge in the tank bringing air or gas into the pump or, for some other reason • is stuck in the mud. Even with the use of self-priming centrifugal pumps, several minutes can pass before effective pump action is restored, and during this time the degassing operation in the tank is affected to a significant extent. Previous attempts to use steam-air centrifugal pumps include a device which is shown in US patent no. 3 815 717, and which is not practical in connection with abrasive fluids such as drilling mud, due to rapid grinding down of the seals. With a construction that is proposed in US patent no. 3 769 779, the seals are avoided, but with the device according to this patent, the released gas must flow into the incoming fluid at one or more points.

In said US patent no. 3769 779, an apparatus for degassing fluids, in particular drilling mud, is shown, comprising a container with an inlet and an outlet for the introduction and discharge of

in the fluid to be treated, a centrifugal pump connected to the container for circulating the fluid through the container and means for removing gas from the region of the impeller in the centrifugal pump. The invention also includes a centrifugal pump designed for handling gas-containing fluids, the pump having means for removing gas from the area of the pump impeller. Furthermore, the invention comprises a centrifugal pump for handling corrosive and/or abrasive fluids where said fluids are prevented from coming into contact with the pump seal by means of a pressurized compartment near the seal.

US patent no. 3,616,599 shows an apparatus for de-

gasification of drilling mud. According to the patent, guide plates are arranged'i

a vacuum tank over which thin sludge films are degassed as they flow down to a receiving area in the tank. A double ejector device of the venturi type is arranged in a sump in the tank for removing degassed sludge and for creating negative pressure at . the upper part of the tank.

In US patent no. 3,241,295, a sludge degassing apparatus is shown with a sludge degassing vacuum tank comprising a sludge inlet. run<p>g a sludge outlet for continuous flow of sludge through the tank, means for keeping the interior of the tank under negative pressure, valve means arranged in the sludge inlet for controlling the speed of the flow of sludge into the tank, means which react to variations in the level of sludge in the tank for to vary the negative pressure in the tank, as well as organs that react to variations in the pressure in the tank for opening and closing the valve organs.

US patent no. 3 249 227 shows a centrifugal separator for treatment (mechanical treatment) of mud, as well as for sorting according to specific gravity of solids in mud, of emulsion components, as well as for degassing drilling mud. The device is suitable for use in the chemical, mining and petroleum industries.

The publication "A Degasser You Can Understand" by Walter E. Liljestrand, presented at the IADC Rotary Drilling Conference in March 1974, contains a description of mud degassing. A degasser' is one of several important components that are necessary on a rig that must be able to process gas in sludge. This paper gives perspective to the whole problem. The atmospheric 'exhaust' described is in principle completely hy. The flow is regulated using the liquid and the pump.

The present invention provides a system for degassing; of drilling mud in a continuous manner as the mud is circulated to and from a wellhead. The present invention provides a centrifugal pump degassing system capable of pumping gas-containing liquids, including drilling fluids, while limiting the flow of gases removed from such gases to pipelines by with the help of which the gases are taken to safe disposal areas. Such a centrifugal pump degassing system involves the transfer of such gas-containing fluids to degassing or venting vessels, or out of such vessels during periods of incomplete degassing.

An embodiment of centrifugal pump degassing system

the cube according to the present invention comprises an impeller designed with a hollow central part which is driven by a hollow shaft through which the gas can be extracted without having to be passed through a fluid-filled zone. A pre-rotational inlet chamber below the impeller releases drilling mud into the impeller housing in a circumferential stream during which the freed gas flows from the vortex 1 chamber and the impeller through the hollow drive shaft and into a single pipe leading directly into the degassing tanks. The impeller cover provides the drilling mud further rotational speed through decreasing radius, which further establishes a central vortex against which any gas escaping from the fluid will be forced due to the sludge up the hollow impeller shaft. Released gas flows in the same axial direction as the sludge through the pump. The drilling mud flows out of the impeller housing through the outlet port and is fed, depending on the pump pressure, into a cylindrical container where it . is ejected, in a radial spray pattern against the wall of the container.. I . the splash pattern is maintained- a central opening which. communicates the container above the spr.out pattern with the part of the container located below the pattern. The spray pattern preferably hits the entire inside of the container and this pattern entails advantages that are not found in other spray formations.

The above as well as other purposes and advantages of the present invention will become clearer from the following detailed description of the invention in connection with the attached drawing, where:

Figure 1 illustrates one degassing system constructed

in accordance with the present invention.

Figure 2 shows on a larger scale, and partially in section, the centrifugal pump device. in the system shown in figure lv Figure 3 shows the splash container on a larger scale and: partially in section. Figure 4 shows a side view. partial in' section, of the gas separator vessel. Figure 4a shows, on a larger scale, a part of the construction shown in figure 4.

In the drawing, and with special reference to fi-

Figure 1 shows an embodiment of a degassing system constructed in accordance with the present invention. Gas-contaminated drilling mud 22 from the mud tank 20 is fed to a mud injection container 29 through line 24 by means of a pump system 14,

A negative pressure which is formed in the container 29 is communicated through .. a line 25 to a top cover■12 with a rotatable seal on

the top end portion of the pump's 14 hollow pump shaft. Sludge is pumped via the line 24 through the wall of the container 29 and sprayed outwards through the spray head 27 where it hits the wall of the container 29 and flows down and out through the bottom outlet pipe 23. From the outlet pipe 23 the sludge flows into the gas separator vessel 28 and flows down the vessel below a manually operated gate 58, down through the return pipe 30 and back into the degassing sludge tank 21.

The pumping system 14 according to the invention provides a centrifugal pump capable of pumping the gas-containing drilling mud 22, while limiting the flow of contaminated gas removed from the drilling mud to the pipeline 25,

by means of which the gas is led via the container 29, the vessel 28

and line 26 to secure disposal areas. The pump system. 14

transfers the gas-containing drilling mud into the syringe container 29. It is well known that conventional centrifugal pumps easily develop vapor pockets which significantly reduce the pump's volume capacity and limit its ability to handle fluids. Previous attempts to produce steam-vented centrifugal pumps include the device shown in US patent 2,815,717 which is not practical for abrasive fluids such as drilling mud due to rapid wear of the seals. The construction shown in US patent 3 769 779 avoids wear and tear of the seals, but here the released gas must flow against the incoming fluid at one or more points.

As can best be seen from figure 2, the pump system 14 according to the present invention uses an impeller 2 designed with a hollow central part which is driven by a hollow shaft 3 through which the gas can be extracted without. to have to be passed through a fluid-filled

zone. A pre-rotation inlet chamber 8 and cover 7 below the impeller 2 allow free fluid into the impeller housing 4 in a circumferential flow. Released gas flowing from the vortices in the chambers

and 8 and of the impeller 2 is carried upwards through the hollow drive. shaft 3, then through the top part of the shaft into a top cover 12 with dynamic seals 12a for sealing against the rotating shaft.

Centrifugal pumping includes an impeller'2 which is rotatable, supported on the shaft 3 and made to rotate in the impeller housing 4 by means of a motor 5 which drives the shaft. 3 via a disc 6a and grazing drive 6. A cover section 7 and a prerotation inlet section 8 are attached to the impeller housing 4. Fluid enters the prerotation inlet section 8 through substantially tangential inlets 9 which give the fluid a circular movement in the direction of rotation of the impeller 2. The fluid must then flow through the cover section 7 in order to reach the impeller and below it gains additional rotational speed due to the reduced radius, which further establishes a center vortex through which any gas that escapes from the fluid can be directed towards the longitudinal axis of the pump shaft and up through the shaft. The liberated gas rises through the central opening 10 in the impeller 2., through the hollow central part 11 of the shaft 3, to the pipeline 2 5 in the double jacket 12.

Fluid under pressure from the rotation of the impeller flows out of the impeller housing through the outlet 19, but also has the opportunity to flow into the space between the impeller 2 and the top part 16 of the housing 4 and into the annular space 17 between the axle 3 and the axle housing 15. When the impeller. is not in motion, the fluid in the annulus 17 will have the same level as the external fluid, but when the impeller rotates, the developed pressure will force the fluid somewhat higher in the annulus 17. To prevent such a level rise, a drain pipe 18 can be arranged through which pressure can be relieved by discharge of the small fluid flow that can penetrate up through the space 17. Furthermore, double screw vane 37 can be attached to the outside of the impeller shaft 3 to give a downward impulse to any fluid flow up through the annular space 17, or an annular dynamic seal can be arranged between the shaft 3 and the housing 15.

Figure 3 shows a section through the spray container. The container 29 generally comprises a cylindrical upper section 29a, a conical middle section 29b and the bottom outlet pipe 23. The sludge inlet line 24 is attached to a transfer collar 32 which is sealed, fixed in the wall of the container 29. A top cover plate 33 is tightly fixed to the top section 29a, for example by means of bolts 34 through a flange 35. An upper outlet pipe 36 communicates with an opening in the plate 3 3<p>g is connected to gas flow line 25.

The spray unit 27 is stored largely centrally in the spray container 29 by means of an inlet line 40 which is again coaxially attached to the collar. 32. The unit 37. generally comprises an outer annular flow vessel 38 which generally includes a.

double-walled cylindrical element with closed bottom and open top.

The enclosed area 39 which consists of the two walls and the bottom

in the vessel 38 is in fluid communication with the pipeline 24 via the collar 32 and inlet line 40.

A guide plate 41 is arranged directly above the annulus 39 and close to the vessel 38. The plate 41 is positioned in relation to the vessel 38 in such a way that a relatively narrow spray gap 44 is formed between these parts. The plate 41 preferably has a larger diameter than the vessel 38 to prevent fluid squirts upwards into the vessel 29. The plate has a central opening in which a cylindrical center coil 42 is attached, which in turn is inserted with a relatively tight fit into the central space of the coil vessel 38.

The center coil' 42 internally has an open, continuous channel 43. The central plate and coil device. is stored

by means of a threaded bolt 45 which at its lower end is screwed to a transversely running support element 46 and -at its upper end to a corresponding transversely running support element 47.. The support element 47 extends over the bore 43 and is attached at each end to the plate 41 f. e.g. by welding or screws. Likewise, the support element 46 extends over the opening 43 and is attached to the bottom at each end.

of the vessel 38 e.g. when welding.

Regulation of the spray gap 44 is achieved by turning the plate 41 clockwise to narrow the gap 44 or counter-clockwise to widen the gap. 44. Rotation of the plate 41 also causes rotation of. the threaded support element 47 which moves the plate and the support element up and down on the threaded bolt 45.

Figure 4 shows on a larger scale a section of the gas separator vessel 28. This mainly consists of an elongated closed flow vessel .50 connected to an inlet chamber 51. At the top, the inlet chamber has an inlet line 52 with an upper annular flange 53, a corresponding flange '48 is arranged at the bottom of outlet pipe 23 of the container 29.

The corresponding flanges 48 and 53 make it possible to place the container 29 on top of the tub 28 where it can be fixed, e.g. using bolts through the corresponding flanges. The inlet pipe 52 is aligned coaxially with the outlet pipe 23 and extends through a substantial part of the chamber 51 to a point near the bottom thereof. An alternative location of the pipeline 52' is indicated by dashed line at 55 for embodiments 'where the height of the unit is limited..

A vertical guide plate 54 is attached to the bottom of the chamber 51 and extends across the chamber from one side to the other. Another plate 72 extends downward from the top of the vessel to a. point above the bottom of the vessel, so that a flow opening is formed under the plate. A pointed roof 5=6 is

hinged to the channel section 50 and completely encloses this vessel section.

The inlet chamber 51 is also completely closed. An outlet opening '57 is provided near the end portion of the channel section 50 and communicates with the sludge return pipe 30. A flow control plate 58 is attached to a float arm 61 which is hinged at 59 to the far end 60 of the vessel. The plate extends substantially across the entire width of the vessel and is located in front of the opening 57.

A float element 62 is attached to the end of the arm 61 opposite the connection 59. A cover plate 66 is attached to the tub's end part 60 and extends forwards over the outlet opening 57. A downward facing front plate 67 is attached to the front edge of the plate 66 close to the regulation plate 58 and so that the latter plate can slide

towards the front plate 67. The plates 58, 66 and 67 preferably extend over substantially the entire width of the vessel 28. One non-return valve 68, which can be of any known type, can be arranged on the plate 66 for the discharge of gas which may have collected itself under the cover plate.

Figure 4a shows a non-return valve which can be used in the plate 66. In this case, a valve damper 69 is hinged to the plate 66 by means of a pin 70 so that the damper in the closed position rests on a . opening 71 through the plate 6'6. Gas pressure below

the plate 66 can penetrate up through the opening 71, lift the damper 69 and into the upper part of the vessel 28. Gas or fluid is prevented from flowing down through the opening 71 by closing the damper. 69.

It should be noted that the port assembly comprising the float 62, the arm 61, and the plates 58, 66 and 67 act to provide a fluid seal between the vessel 38 and the outlet opening 57 to prevent gas from flowing through the opening 57. To further prevent gas flow through through the opening 57, the outlet pipe 30 can extend upwards a predetermined distance above the bottom of the vessel 38. This distance can be chosen. so that the top edge of the pipe 30 is higher than the bottom edge of the plate 67.

A gas outlet pipe 63 is passed through the pointed roof 56 and is attached to a gas flow line 26. One or more vertical guide plates 64 extend over a substantial part of the width of the vessel 28 and extend downwards towards the bottom of the vessel. The plates 64 can be welded or fixed to the sides of the vessel and are open in the pointed roof section 56. In one embodiment, the roof section 56 had an inclination of 45° with the apex located approximately midway along the roof section.

In typical use, the mud-gas separator unit according to the present invention can be mounted at a well drilling area and placed on the mud tanks 20 and 21, e.g. by means of stirring elements 65 which extend across the tank 20. The motor-driven pump unit can also be stored on the tank side by means of pea

suspension device or other known device. The drilling fluid is pumped into the tank 20 from the drilling area preferably through

a device that removes solid substances such as rock residues and sand from the drilling mud.

The pump motor is started and fluid is sucked into the tangential inlets 9 in the chamber 8 and. upwards through the cover 7 after which the impeller 2 throws it out through the outlet 19.

A vortex forms in the middle of the hollow impeller part at 10

and gas bubbles that are separated from the sludge in the centrifugal pump are moved inwards to. the area 10 as a result of the heavier mud being moved outwards in reaction to the centrifugal forces acting on the mud due to the rotation of the impeller. The separated gas is led upwards through the hollow middle part 11 of the shaft 3 and out through the top of the hollow shaft, which is sealed by means of the top cover 12.

The pumped sludge is fed through the outlet 19 into the pipeline 2 4 and then upwards into the spray container 29.

At the spray container 29, the sludge is fed through the collar 32 into the line 40 and the annulus 39. The sludge is forced under high pressure out through the narrow slot 44 towards the guide plate'41 in the form of a circular splash outwards from the plate 41 towards the inner surface of the outer wall of the container 29 The fluid spray has a "doughnut shape" with a open party at 43.

The spray action outwards against the container's wall produces a strong negative pressure in the upper part of the container above the spray. The flow towards plate 41 produces strong "turbulence" and shear forces in the fluid, which causes many small enclosed gas bubbles to unite into larger bubbles. The strong negative pressure that forms in the upper part of the chamber appears to be a result of the venturi effect of the outwardly directed spray. and the open central channel 43.

The formation of a strong negative pressure acts very advantageously to pull the small bubbles in the fluid together and out of the fluid. The negative pressure is also beneficial in its effect on the centrifugal pump 14. The negative pressure communicates with the pump 14 through the pipeline 25. This further acts to suck away the gas that is secreted in the pump at the central opening 10.

. The negative pressure also works to improve the pump's efficiency by reducing air pocket and cavitation conditions in the impeller area and by contributing to the intake of fluid in the pump as a result

of the oppressed.

The negative pressure that forms in the upper part of the container 29 thus has several purposes. It helps to unite small bubbles into large bubbles, it helps to suck the trapped gas bubbles from the fluid both in the container 29 and in the pump -14 impeller area, and it helps in several ways to improve the efficiency of the centrifugal pump.

The sludge is emitted through the spray gap 44 in a continuous layer and impinges on the wall of the container 29, and flows downwards along this until it reaches the outlet pipe 23 from which it flows into the separator vessel inlet 52. The fluid flows down to the bottom of the chamber 51, back up above the upper edge of the guide plate 54, and down again under the plate 72. The plates 54 and 72 prevent open communication from the upper part of the channel 50 to the container 29. This acts to maintain the strong negative pressure in the container 29.

If the plates 54 and 72 were removed, the negative pressure area in the container 29 would have open communication with the outlet line 26 and the negative pressure would gradually be reduced. The arrangement of the guide plates forms narrow openings at the top of the inlet chamber and at the bottom which are generally filled by the fluid flow from the line 52, so that an effective liquid seal is formed which prevents open gas communication.

In the container 29, small gas bubbles unite into large bubbles that flow through the line 52 in the drilling fluid over the guide plate 54, under the plate 72 and into the vessel section. Although the bubbles are still there. in the fluid, the turbulence and vacuum effect in the container.29 has meant that the bubbles have acquired a size during fusion that provides sufficient buoyancy for the bubbles. can rise to the top of the fluid flow in the closed vessel section 50. The baffle plates 64 delay flow of the foamy upper fluid level containing the highest concentration of gas bubbles, so that the bubbles have more time to break out of the sludge.

The entire operation of the degassing system depends to a large extent on the small trapped gas bubbles being fused into larger bubbles so that their total buoyancy is sufficient to overcome the inertia and viscosity of the heavy fluid in which they are trapped. The operation of the present invention is advantageous in that the outlet gas which collects at the top of the vessel section 50 is under a net excess pressure and therefore flows freely from the vessel section through the hose 26 without the need for mechanical removal means

■ such as a vacuum pump or fan. The resulting gas overpressure in the vessel section 50 is apparently a result of the hydrostatic head of the fluid in the container 29 acting throughout the closed container 29 and the vessel 28. An optimal fluid level is maintained in the vessel by means of the port 58 which is preferably connected with an adjustable float element 61 to maintain the predetermined fluid level.

It should also be pointed out that one of the important parameters that affects the gas separation process is the time it takes for the fluid to flow through the separator vessel. A vessel with insufficient length for the given flow rate of the drilling fluid will not provide sufficient time to achieve an acceptable gas separation rate due to the fact that. the small bubbles get . too little time - to overcome fluid inertia and viscosity and rise to the surface. ten.

In a particular embodiment, it was found that a vessel length of approximately 2.4 meters gave a gas removal rate of approximately 85% in a sample sludge pumped at a rate of 3.8 l/min. Any increase in the length will give a small increase in the percentage amount of gas that is removed from the fluid. Other methods of increasing the residence time of the fluid in the separator vessel include lowering the pump speed, increasing the cross-sectional area of the vessel, and changing the depth of the drilling mud in the vessel.

It will thus appear that with the present record. invention can achieve many advantages when degassing drilling mud. Thus, the need for a mechanical vacuum pump or blowing device to remove any dangerous gases from the separator unit is eliminated. Another advantage is the significantly better efficiency of the centrifugal pump as a result of the negative pressure in the impeller-vortex area. A further advantage is that gases removed from the pump vortex area are captured and these gases are transferred to a section of the container where they can be captured and taken to a secure disposal area.

Further advantages lie in the very effective fusion of small gas bubbles into the more easily removable large bubbles as a result of the strong negative pressure in the spray container and the very effective removal of the bubbles as a result of the separator vessel's efficient construction. Other advantages, which are not mentioned here or which are not readily apparent from the description above, will become apparent from the practice of this invention.

Although a particularly preferred embodiment of the present invention has been described in detail, this description must not be regarded as a limitation of the invention to the particular embodiments shown here, as these must only be regarded as illustrative and not limiting, and it will be It will be clear to a person skilled in the art that the invention is not so limited.

Thus, although the spray container 29 is described as a cylindrical container, it is clear that other designs of this container could be used, such as square, rectangular, oval, etc. Furthermore, even if an impeller pump of the centrifugal pump is used in connection with this invention, it will be clear that other types of fluid pumping apparatus may work with this invention. Furthermore, although the sludge gas separator vessel 28 is described as a rectangular container with an elongated expansion channel with a pointed roof, it is clear that other cross-sectional designs of the vessel can be used, such as a U-shaped vessel or a circular vessel. A further modification would be to arrange a gas line from the upper part of the container 29 to the lower part of the container instead of the communication through a middle opening 43 in the spray unit 27. The invention is thus declared to cover all changes and modifications of the particular example of the invention which is shown and described here which does not deviate from the inventive recognition and framework.

Claims (51)

1. Method for removing a significant amount of trapped gas from a viscous fluid such as a drilling mud, characterized by introducing the fluid into a fluid pump while pressurizing the introduced fluid, discharging the pumped fluid through a pipeline and into a crispy finish holder, spraying the fluid outwards from a baffle device. into the spray container in a 360° radial spray pattern with a central opening, directing the sprayed fluid to an outlet in the spray container, discharging the fluid into a closed degassing container, directing the fluid through an elongated portion of the degassing container while maintaining a fluid barrier against gas flow between the elongated part of the degassing container and the syringe container and emptying the fluid from the degassing container and collecting the gas that has been removed from the fluid in the degassing container. 2. Procedure for degassing as stated in claim 1, characterized by communicating • of the syringe container-■ clean upper part with the fluid pump to further remove gas from the fluid in the pump, prevent pump vapor pockets, and increase the intake of fluid in the pump. 3. 'Procedure for degassing as specified in claim 1, characterized by lowering the flow rate of the upper layer of fluid flowing through the degassing container. 4. Procedure for removing small and large trapped gas bubbles from a viscous fluid and collecting the removed gas for safe disposal, characterized by placing a fluid pump's inlet opening in the fluid, introduction of. fluid in, the inlet opening during operation of the pump, simultaneous formation of an open vortex in the pumped fluid, discharge of the pumped fluid through an outlet line, introduction of the pumped fluid from the outlet line into a syringe container, ejection of the pumped fluid against a guide plate in the container in such a way that ■ a negative pressure is formed in the upper part of the spray container in relation to the atmospheric pressure outside the container, communicating the pump-vortex area with the upper part. part of the container, transferring the fluid from the container to a closed degassing tank while maintaining a fluid barrier between the open areas of the container and the tank, passing the fluid through the tank while lowering the flow rate to the upper layer of the fluid, draining the fluid from lower part of the tank and the removed gas from the upper part of the tank into predetermined outlet openings. 5. Procedure for removing trapped gas bubbles from a fluid for safe disposal, characterized by placement of a fluid pump's inlet opening in the fluid, suction of fluid into the pump during operation of the pump, discharge of the pumped fluid into an outlet opening, communication of the outlet opening with a closed syringe container, ejecting the fluid in the syringe container against a baffle element to force small gas bubbles to coalesce into larger bubbles, guiding the fluid out of the syringe container into a closed flow container, maintaining the flow container partially filled with flowing fluid and sen- . control of the flow rate to the upper layer of the fluid. to help remove trapped gas bubbles from the fluid, collection of a substantial part of the removed gas bubbles in the upper part of the flow container, - removal of the collected gas to a safe disposal area,' and emptying of the degassed fluid from lower part of the turbulence container. 6. Procedure for degassing drilling fluid, characterized in that it includes placement in drilling the fluid of a centrifugal pump with inlet means and outlet means and a hollow drive shaft that drives the impeller, introduction of fluid into the pump through the inlet means by rotation of the shaft and the impeller while maintaining an open central vortex in the fluid in the impeller section, pumping the fluid through the outlet -the body.into a closed spray container and against a guide plate, whereby a radial spray is formed against the container wall while maintaining communication from the container area under the spray • to the container area above the spray, communicating the upper part of the brittle surface container with the hollow drive shaft, passing fluid downwardly out of the bottom of the brittle surface container into an underlying closed vessel, passing fluid through a narrowed opening in the vessel to form a - blocking open gas communication between the vessel and the spray container, guiding the fluid down through the vessel length with a sufficient distance for a significant amount of the gas to bubble out of the fluid and emptying the fluid and the removed gas from the fluid and gas outlets in the vessel respectively. 7. Method for removing trapped gas bubbles from a fluid, characterized in that it comprises guiding the fluid into an inlet line in an elongated flow vessel, guiding the fluid past a liquid barrier near the inlet, thereby preventing communication of the gas pressure from the vessel through the inlet, guiding the fluid down the elongated vessel while lowering the flow rate to the upper fluid layer, collection of released gas bubbles in the upper part of the vessel and removal of the gas bubbles through a gas outlet, leading fluid past another fluid barrier and into an outlet line. 8. Method for introducing shear forces into a fluid containing trapped gas bubbles to help unite small bubbles into large bubbles, while simultaneously creating an advantageous negative pressure above, characterized .by placing a radial brittle surface unit inside a closed spray container, introduction of fluid under pressure into the spray unit and radiation of the fluid outwards in a continuous radial spray layer against the container wall, arrangement of gas communication from the container area below the spray to the container area above the syringe, and draining the fluid from the syringe container. 9. Method according to claim 8, where the radiation step comprises squeezing out the fluid through a circular annular gap towards a nearby guide plate. 10. Method for uniting small gas bubbles enclosed in a fluid into larger bubbles, characterized by pumping the fluid through a centrifugal pump with a hollow shaft, formation of an open central vortex in the fluid in the pump, which communicates with the bore in the hollow shaft, pumping the fluid from the pump into a spray unit in a closed container, ejecting the jet radially outwards in a continuous layer against - the inner wall of the container, arrangement of gas communication from the container area below the radial spray - to the container area above the spray, and communication of the upper part of the container with the bore in the hollow shaft. 11. System for degassing drilling fluids from a borehole, . characterized by a pump device designed to pump, drilling fluid and equipped with inlet and outlet, a syringe container fluid-wise. connected to the outlet as the spray container includes a closed container with an inlet line, a spray-. unit and an internal guide plate, as well as an outlet opening, a degassing container in a position below the brittle surface container and in fluid communication with the outlet opening, the degassing container being substantially closed and airtight, with a gas outlet opening and a f luid outlet opening.' 12. System according to claim 11, characterized. in that the spray container is located above the pump:! sufficient distance to lie above the drilling fluid level. 13. System according to claim 12, characterized in that the spray container is closed to the atmosphere and further comprises a gas suction opening.. 14 . System according to claim 13, characterized in that the pump is a centrifugal pump with. one central opening in the impeller. in communication with the gas suction opening. 15. System according to claim 13, characterized in that the degassing container comprises means for maintaining a liquid seal between the gas outlet opening and the rest of the degassing container. 16. Closed system for removing a significant portion of trapped gas from a fluid such as drilling mud, which system is substantially isolated from the atmosphere, characterized by a power-driven fluid pump having inlet means for placement in a drilling fluid tank and outlet means for draining fluid pumped from a tank, a closed spray container with an inlet pipe connected to said outlet means and an internal spray unit connected to the inlet pipe, which spray unit is adapted to emit pumped fluid in a radial spray pattern inside the container, a fluid outlet opening in the lower part of the spray container and a gas suction opening in the upper part of the container, and a degassing vessel which is substantially closed to the atmosphere, and which at one end has an inlet which communicating with the fluid outlet port, a fluid outlet near the opposite end and a gas outlet port near the top. 17. System according to claim 16, characterized in that the fluid pump has means for removing gas bubbles which are released in the pump, which removal means. communicates with the gas suction opening in the spray container. 18'. System according to claim 16, characterized by first blocking means in the vessel to prevent gas communication between the open area inside the vessel and the open area inside the spray container. 19. System according to claim 16, characterized by other blocking means in the vessel designed to maintain a fluid barrier against gas flow from the vessel -out of the fluid outlet..- . 20. System according to claim 17, characterized in that the fluid pump comprises a centrifugal pump with a vortex opening through the impeller and a hollow elongated shaft, which is connected to the impeller and communicates with the vortex opening. 21. Degassing vessel for removing gas bubbles that are contained in viscous fluids such as drilling mud, grade-i. - ■s e r t in that it comprises a closed inlet section with an inlet opening, a flow section which is connected to the inlet section and is relatively air-tight, a narrowed flow opening between the inlet and flow sections arranged to up- . maintain a liquid barrier against open communication of gas between the two sections, gas outlet means in the flow section, and fluid outlet means in the flow section. 22. Degassing vessel according to claim 21, characterized by guide means arranged across the upper part of the flow section. 23. Degassing vessel according to claim 21, characterized in that the inlet section comprises a closed chamber with an inlet line which communicates via the outlet opening with the lower part of the chamber, and that the narrowed flow opening comprises a vertical guide plate which extends over the chamber. and along its bottom upwards to a point a predetermined distance below, the top of the chamber and above the bottom of the inlet conduit. .. 24. Degassing vessel according to claim 21, characterized in that it comprises fluid level regulating means in the flow section to maintain the fluid level in the section within a predetermined desirable frame. 25. Degassing vessel according to claim 24, characterized in that the regulating means comprise a hinged damper, arranged to change the flow area for fluid flow through the fluid outlet means, and float means attached to the damper and arranged to move the damper in response to the fluid level in the flow section. 26. Degassing vessel - to help remove trapped gas bubbles from fluids, characterized in that it comprises an inlet chamber having a fluid inlet line and is closed to the atmosphere, an elongated flow vessel connected to the inlet chamber and sealed to the atmosphere, blocking means in the inlet chamber to form a liquid seal between the chamber and the flow vessel, fluid outlet means in the flow vessel, gas outlet means in the flow vessel, means in the flow vessel for retarding the upper flow level, and fluid level control means in the flow vessel. 27. Degassing vessel according to claim 26, characterized. in that the blocking means comprise a vertical guide plate which extends across the width of the inlet chamber from its bottom to a point a predetermined distance from the top of the chamber, and located between the inlet line and the flow vessel. 28. Degassing vessel for removing trapped gas bubbles from fluids, vessel acting in that it comprises a closed inlet section with an inlet line, a flow channel which is connected to the inlet section and closed to the atmosphere, first blocking means in the inlet section for . to form a liquid-tight . ning between the inlet section and the flow vessel, a fluid outlet line in the flow vessel, other blocking means in the flow vessel at the outlet line to form a liquid seal between the vessel and the outlet line, and gas outlet means in the flow vessel.. 29. Degassing vessel according to claim 28, characterized in that the other blocking means comprise an adjustable, float-controlled gate arranged to form a variable flow opening through the vessel to said outlet line in response to the fluid level in the vessel.. 30. Degassing vessel according to claim 29, characterized by closing means in the vessel, above the outlet line, close to the gate, and with an opening near the bottom of the vessel which communicates with the variable flow opening. 31. Degassing vessel according to claim 30, characterized by one-way gas outlet opening means in the closing means arranged to release trapped gas upwards through it. 32. Syringe container assembly for use in a degassing system, for a viscous fluid, characterized in that the container assembly comprises a generally vertical, peripheral wall section which forming a container, a top part sealingly attached to the vertical wall section, a lower container section closing the bottom of the vertical section, inlet means leading into the container, fluid outlet means in the container below the inlet means, and spray guide means in the container, connected to the inlet means-and arranged to spray a radial spray pattern against the inner wall of the container. 33. Container unit according to claim 32, characterized by gas line means above the spray guide means arranged to communicate the interior space of the spray container with an outer line. 34. Syringe container unit according to claim 32, characterized in that the syringe guide means comprise a double-walled chamber which is connected to the fluid inlet means and has . an open axial end, and a guide plate near the open chamber end with . a central coil connected to the guide plate extending downwards in a closely fitted relationship within the inner wall of the double-walled chamber. 35. Spray container unit according to claim 33, characterized in that the double-walled chamber and the guide plate generally have a circular shape, both having open middle sections, and that the guide plate extends radially outward past the ring chamber. 36. Syringe container unit according to claim 32, characterized in that a vertical wall section forms a circular, straight cylinder, that the lower container section has a conical truncated shape and is coaxial with the vertical section, and. that the fluid outlet comprises a narrowed cylindrical section which is attached to the conical section. 37. , Syringe container unit according to claim 34,, k a r a k - t e ri ser t by regulating means between the chamber and the guide plate to enable controlled regulation of the intermediate gende column. 38. Spry surface container unit according to claim 32, characterized in that the spry teledeorganen.e is. arranged to spray a substantially continuous layer of fluid, from the spray deflector plate to the outer wall of the container. 39. Syringe container unit according to claim 32, characterized by gas communication means which communicate the area in the container above the brittle surface guide means with the area in the container below the spray guide means. -v 40. Syringe container system for shear action in a heavy fluid to unite -small trapped gas bubbles in the fluid. under, formation of a negative pressure by movement of. the fluid, 'characterized by a generally vertical enclosed container with sealed top and bottom, fluid inlet means which are led re-.: nom a wall in the container and into its interior space, fluid outlet means 1 lower part of the container, gas conduit means in the upper part of the container, and a spray unit arranged inside the container and arranged to emit a radially outwardly directed spray emoen,s ter towards the inside of the container wall, with gas communication from above the spray unit to below the spray unit. 41. Spray container system according to claim 40, characterized in that the spray unit comprises an annular chamber. with two "concentric vertical walls and an annular bottom plate. with .a central through opening, and a guide device with a flat annular plate and an attached open center coil, which guide plate is near the top of the vertical walls and forms an annular gap with the outer wall, as the coil is designed to fit tightly into the inner vertical wall. 42. Syringe container system according to claim 41, characterized by means for regulating the size of the ring gap. 43. Container system according to claim 42. characterized 'in that the regulating means comprise a threaded rod which, in its top part, is screwed into a transversely running element which extends over the guide plate's central opening and is fixed to the guide plate, and in its bottom part is screwed into a cross-running element which extends over the ring.chamber's central opening and is fixed to the ring-shaped bottom plate. 44. Closed pump for use in pumping fluids with trapped gas, characterized by an impeller having a through central axial opening, an impeller housing enclosing the impeller and having discharge-outlet means, inlet-opening means attached to the housing and communicating with the radially inwardly directed portion of the impeller, an elongate shaft which is attached to the impeller and has a longitudinal through channel which communicates with the central opening of the impeller, drive means; which is operatively connected to the drive shaft for rotation of the shaft, and gas discharge means on the drive shaft which communicates with the channel. 45. - Fluid pump according to claim 44, characterized in that the inlet opening means comprise a pre-rotation chamber with one or more inlet channels formed around the outer wall of the chamber, and' that the chamber is located below and is attached to the impeller housing. seen. 46. - Fluid pump according to claim 44, characterized by an impeller cover on the impeller housing between the inlet opening means and the impeller's central opening. 47. Fluid pump according to claim 46, characterized in that the impeller cover comprises a narrowed section which forms • a. Downward-facing part of the Christmas tree house. 48. Fluid pump according to claim 44, characterized by a shaft housing which concentrically surrounds the drive shaft, is 'tightly attached' to the impeller housing, and extends a significant distance along the elongated drive shaft... 49. Fluid pump according to claim 44', characterized in that the gas discharge means comprise a cover on top of the drive shaft, that the channel extends through the top part of the drive shaft and communicates with the cover, that the cover is internally provided with a dynamic sealing means for sealing engagement with the drive shaft during rotation, and that the casing has a continuous outlet line. 50. Fluid pump for pumping heavy viscous fluids such as drilling mud, in which fluids gas is contained, characterized by the fact that it comprises an elongated hollow drive shaft. a centrifugal impeller attached near one end of the drive shaft and having a through central axial opening, an impeller housing enclosing the impeller and having discharge outlet means through its wall, an inlet chamber attached to the impeller housing and having inlet opening means through its wall , a narrowed section in the impeller housing between the impeller and the inlet chamber, a shaft housing that is sealingly attached to the impeller housing and encloses a substantially equal length of the drive shaft, bearing means for rotatably supporting the drive shaft, drive means attached to the drive shaft for rotation of the drive shaft, and means that seal communicates with the cavity in the drive shaft for the passage of gas from there. 51. Fluid pump according to claim 50, characterized in that the drive means comprise a motor with a rotary. output shaft, a drive pulley connected to the output shaft, a driven pulley connected to the drive shaft, and flexible drive means in engagement with both pulleys.