EP2796663A2 - System und Verfahren zur Analyse eines Bohrlochgas - Google Patents

System und Verfahren zur Analyse eines Bohrlochgas Download PDF

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Publication number
EP2796663A2
EP2796663A2 EP14161601.1A EP14161601A EP2796663A2 EP 2796663 A2 EP2796663 A2 EP 2796663A2 EP 14161601 A EP14161601 A EP 14161601A EP 2796663 A2 EP2796663 A2 EP 2796663A2
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EP
European Patent Office
Prior art keywords
mud
gas
degasser
analyser
drilling mud
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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EP14161601.1A
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English (en)
French (fr)
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EP2796663A3 (de
Inventor
James Harrison
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HRH Ltd
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HRH Ltd
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Publication date
Application filed by HRH Ltd filed Critical HRH Ltd
Publication of EP2796663A2 publication Critical patent/EP2796663A2/de
Publication of EP2796663A3 publication Critical patent/EP2796663A3/de
Withdrawn legal-status Critical Current

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    • E—FIXED CONSTRUCTIONS
    • E21—EARTH OR ROCK DRILLING; MINING
    • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B49/00—Testing the nature of borehole walls; Formation testing; Methods or apparatus for obtaining samples of soil or well fluids, specially adapted to earth drilling or wells
    • E21B49/005—Testing the nature of borehole walls or the formation by using drilling mud or cutting data
    • E—FIXED CONSTRUCTIONS
    • E21—EARTH OR ROCK DRILLING; MINING
    • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B21/00—Methods or apparatus for flushing boreholes, e.g. by use of exhaust air from motor
    • E21B21/06—Arrangements for treating drilling fluids outside the borehole
    • E21B21/063—Arrangements for treating drilling fluids outside the borehole by separating components
    • E21B21/067—Separating gases from drilling fluids

Definitions

  • This invention relates to a system and method for analysing gas emitted from boreholes, especially using mass spectrometry.
  • Gas emitted when drilling boreholes can be analysed in order to determine its characteristics and to infer properties of the formation, such as the nature of any hydrocarbons present.
  • the gas from the new borehole is often entrained or dissolved in the circulated drilling mud.
  • traps are provided to provide a continuous gas in air flow from the borehole site to a mud logging cabin where it is analysed using a chromatograph.
  • a system for analysing gas from a borehole comprising:
  • the portion of gas being transferred to the analyser typically in a sampling mode may be referred to as a gas sample batch.
  • the analyser is a mass spectrometer.
  • the system includes a pump to transfer mud from an input to the degasser.
  • the degassing normally occurs for a longer period, such as at least forty seconds , at least one minute, at least one minute twenty seconds or at least one minute forty seconds. Certain embodiments degas for around two minutes. Normally the degassing time is less than five minutes, more normally less than four minutes, and may be less than three minutes.
  • the degasser may have a fragmentation chamber with a mechanism to facilitate degassing of fluids.
  • the degasser may have a rotatable cone, and mud is directed into the cone and in use centrifugal forces direct the mud outwards and over the top of the cone.
  • a degasser for degassing drilling mud, the degasser comprising a fragmentation chamber with a mechanism to facilitate degassing of fluids and a rotatable cone.
  • the fragmentation chamber may be a chamber e.g. cylindrical, extending downwards from an inlet to the degasser. Normally the fragmentation chamber is, in part at least, within the cone.
  • the mechanism to facilitate degassing may include rotating and/or non-rotating blades, or a slotted plate.
  • the slotted plate may be a spiral plate or may be substantially planar.
  • a substantially planar plate may have a fin extending out of the plate.
  • the mechanism to facilitate degassing may include at least one wiper, moveable (e.g. rotatable) with respect to a wall of the fragmentation chamber.
  • the at least one wiper may be spaced from or in contact with the wall of the fragmentation chamber. For example spaced 0.5 - 4mm therefrom or 1.5-4mm therefrom.
  • the cone may have a castellated upper edge.
  • the system may comprise a metering vessel, normally below and in fluid communication with the degasser, being adapted to meter an amount of drilling mud, and normally an activation mechanism comprising a sensor and an activator; the sensor operable to sense an amount of drilling fluid in the metering vessel and the activator adapted to initiate the transfer at least a portion of the removed gas to the analyser, when the amount of drilling mud reaches a certain pre-determined amount.
  • the metering vessel is able to provide two or more successive samples with approximately the same amount of drilling mud.
  • the amount need not be known in absolute terms, for example, by volume or litres, since its primary function is to have a consistent sample size.
  • the senor is a level sensor to determine when a certain level of drilling mud is present in the metering vessel.
  • the amount which triggers the activator may be changed. For example, it may be set at 50% or 25% metering vessel mud volumes/levels, for example if the mud included relatively high gas levels.
  • Certain sensors can also provide a rate of change in the mud level in the metering vessel and they may also be used as a mud flow measurement and this may be used as part of the mud flow control.
  • the time for the mud level to reach a certain amount for example, 50% of the desired amount can be measured and if this is too slow or too fast, a pump can be adjusted automatically or manually to correct the vessel fill time during the remainder of the fill.
  • the fluid communication between the degasser and metering vessel may be adapted in use to block gas communication and allow generally liquid communication.
  • a weir may be provided over which liquid can drop or otherwise proceed towards the metering vessel below.
  • the liquid build-up in use in front of the weir inhibits ambient gases from entering the metering vessel.
  • the degasser may be continuously supplied with drilling mud.
  • the system may comprise a heater, to heat the mud, typically upstream of the degasser. Said heater may be downstream of the pump.
  • At least part of the gas removed from the drilling mud is removed in a transfer line.
  • the system is configured such that the transfer line is closed to the degasser during degassing.
  • the system may also include a dilution line which is configured to have air or other dilution gas pumped into it.
  • Certain embodiments of the invention allow the air in the dilution line to circulate through the transfer line during the degassing mode.
  • the system may be configured to do one or more of (i) closing any connection between the dilution line and the transfer line (ii) removing the mud from the metering vessel, (iii) opening the degasser to the transfer line, (iv) pumping gas from the degasser to the mass spectrometer.
  • the system may be configured to proceed with a purge mode.
  • the purge mode may include adding dilution gas into the degasser. In certain embodiments this is added at a higher pressure, to cause a surge.
  • the pump to circulate the gas in the dilution line may be continuously operated during the sampling mode, so as to build up pressure in the dilution line, the pressure is then released to purge the degasser.
  • sampling mode and purge mode together normally take at least 10 seconds, more normally at least 20 seconds, often more than 30 seconds. Typically they take less than two minutes, preferably less than a minute.
  • the system has an input, upstream of the degasser and any heater, and the input normally comprises a filter, such as a mud suction filter normally with a mounting device.
  • a filter such as a mud suction filter normally with a mounting device.
  • the input may be located in a line connected to a mud return line from the borehole or a mud tank.
  • a cleaning mechanism may be provided for the filter, the cleaning mechanism being configured to direct fluid through the filter in an opposite direction to the normal flow of fluids from the input to the degasser; thus preferably dislodging debris and/or blockages on the filter.
  • the cleaning mechanism may be configured to accumulate fluid from the line between the input and the pump, for example in a cylinder, and then periodically eject it through the filter in the said opposite direction.
  • the cylinder's stroke may use an air operated vacuum device and the discharge stroke may use compressed air from an adjacent reservoir.
  • other devices may be used such as a spring or weighted return.
  • the invention also provides a cleaning mechanism for a system for analysing gas from a borehole, the cleaning mechanism being configured to accumulate fluid from the line between a filter and a pump and periodically direct it through the filter in the opposite direction to the normal flow of fluids from the filter to the degasser.
  • drilling mud is normally used drilling mud.
  • "Used” drilling mud means drilling mud which has been used to facilitate the drilling of a borehole.
  • certain embodiments are configured to degas at least 2 litres, and normally at most 20 litres of drilling mud.
  • a method for analysing gas from a borehole comprising:
  • the method of the second aspect of the invention may be used with the system of the first aspect of the invention and preferred and optional features for the former and also preferred and optional features for the latter.
  • the analyser may be a mass spectrometer.
  • the borehole is a borehole in a hydrocarbon bearing formation.
  • the gas is a hydrocarbon containing gas.
  • a heater apparatus for heating drilling mud comprising:
  • drilling mud is directed through the spiral channel, such that heat is exchanged from the heater element to the drilling mud.
  • the heater used in the third aspect of the invention may be used as the heater for embodiments of the first and second aspect of the invention.
  • the drilling mud used in the third aspect of the invention is normally a used drilling mud.
  • Using such a heater facilitates cleaning of the heater since the cover may be removed and direct access to the spiral channel obtained.
  • a spiral-shaped channel may function as a heat exchanger and be provided normally as a close fit to the surface of the heater element with, in use, any air in the gaps may be displaced with heat conductive liquid such as oil.
  • the heater element is an electrically heated tube and is preferably suitable for zone 1 operation.
  • the external surface of the heat exchanger has a machined spiral groove to form the spiral channel.
  • the invention also provides a feedback system for the system and method described herein, where data from one or more of the following variables is recorded:
  • the nature of the mud may include its temperature, viscosity, specific gravity and content (e.g. water based or oil based).
  • the data regarding the gas recovered from the mud may include its quantity and chemical composition.
  • the data regarding the configuration of the sampling system may include the lengths of the connections between various components, for example the suction head and pump, or the degasser and suction head.
  • the data regarding the sampling rate may include data on the time taken to process samples of mud.
  • Figs. 1a . 1b show a schematic view of a system 10 in accordance with the present invention
  • the system 10 is used to batch sample returned drilling mud from a wellbore being drilled, de-gas it and analyse the gas using a mass spectrometer 50.
  • the data gained from the mass spectrometer 50 is used in turn to elicit information as to hydrocarbon content and/or nature of the borehole being drilled.
  • a mud pump 12 draws mud through a suction head input 14, which is then directed through a mud heater 16 and onto a degasser 20 and associated metering vessel 30.
  • the mud in the metering vessel 30 When the mud in the metering vessel 30 reaches a predetermined level it defines the mud volume which has been degassed for that batch and initiates a sequence which draws off a portion of the gas and air from the degasser head and passes this to the analyser as a sample pill. The degasser is then purged to remove any gas from the previous batch and starts a new mud degassing cycle.
  • the inventor of the present invention has found that the use of batch sampling in this context has some important benefits, which far outweigh the periodic nature of the analysis. For example, since the well gas is accumulated within the degasser head over a period it is possible to use much lower mud flows and this in turn permits the use of much smaller well site equipment. This has a number of benefits which will be become apparent following the detailed description of the present embodiment.
  • Mud returning from a bore hole on a drilling rig or platform can be sampled by accessing a mud tank or a mud return pipe using suction head 14.
  • the suction head 14 includes a filter 15 which filters out any particles greater than 3mm.
  • the suction head 14 is located in the most suitable position in a rig mud system and has means to remove its head for inspection or replacement.
  • the mud suction point may also incorporate an air operated device 9 which indicates if the level of the mud around the suction point is low and this may be used to stop the mud pump to avoid drawing air into the mud system.
  • the mud is displaced using a diaphragm pump 12 which is connected to an air pressure/ flow controller (not shown).
  • This type of pump is very small and can therefore be located very close to the mud source, minimising suction problems. It is also inexpensive and very reliable; all in marked contrast to the accepted use of peristaltic pumps for such applications.
  • the inventor of the present invention has gone against normal practise, and found that provision of a metering vessel 30 downstream of the pump, inter alia, obviates the requirement for a large and precise peristaltic pump because accurate measurement of the sample size is not controlled solely by the pump in the present system.
  • the mud moves through the intake line 11a from the suction head 14, by action of the pump 12 through a heater 16 and onto the degasser 20 and metering vessel 30.
  • a cylinder 13 is provided on a branch of the intake line 11a between the suction head 14 and pump 12, and draws a portion of mud into the cylinder 13 during normal operation.
  • the cylinder's 13 suction stroke may use an air operated vacuum device and the discharge stroke mas use compressed air from an adjacent reservoir.
  • Pumped mud systems have an inherent tendency for a suction head having a filter, such as the filter 15, to block up with drill cuttings and caked mud.
  • the cylinder 13 periodically discharges the mud collected therein back through the mud suction head 14 (referred to as "blowback") to dislodge any cuttings or mud trapped in the filter surface.
  • blowback the mud suction head 14
  • this is particularly suitable for the batch sampling system in the present invention, since the blowback from the cylinder 13, which may include mud accumulated over a period of time and so not be representative of the nature of the mud entering the system, can be timed such that when it reaches the degasser 12, it is the small portion which is not used in the mud sample cycle. In this way, any unrepresentative mud sample from the cylinder 13, will not distort the results.
  • the blowback from the cylinder 13 can be used on each batch or infrequently as necessary, depending on mud or other conditions or user preferences.
  • the mud pump 12 and cylinder 13 may be combined into one assembly which can be secured to a wall of a header tank or adjacent to a flowline.
  • the cylinder 13 may be used to draw mud into the line, part of the way towards the pump 14, and this is especially useful when the line between the suction head 12 and pump 14 s longer. This can assist in priming the pump 14.
  • the illustrated embodiment shows a dual pump 12.
  • the line 11a from the suction head 14 continues on the exit side of the pump towards the heater 16.
  • An alternative exit line 11b from the dual pump 12 is an optional addition to the system and not necessary for many embodiments of the present invention.
  • the diaphragm pump 12 can have two pumping chambers which for certain applications work in parallel as single pump.
  • the pump has a single input but two independent but identical outputs 11a, 11b.
  • the second output 11b can be used for two useful operational modes: (i) a dual sampling mode and (ii) a total gas monitoring system.
  • An added benefit of modes is that the pump can be operated in its more stable range. Indeed, diverting one of the outputs back to the mud tank this is a third option where it is still preferred to run the pump in a more stable range. Nevertheless, a variety of different pumps may be used with embodiments of the present invention and may have different optimum operating ranges.
  • FIG. 2a A second embodiment of a gas analysing system is shown in Fig. 2a and Fig. 2b .
  • Like parts share common reference numerals except prefixed with a '1' and are not described further.
  • Fig 1a / 1b or 2a/2b embodiment where a longer heating time is required, for example with cold muds or where degass mud at high temperatures is required, two heating and degassing loops can be run using the same pump but with the gas sampling times out of sequence. This will effectively permit the user to process one four minute heating cycle every two minutes.
  • the only additional equipment will be a heater and the degasser/ vessel and these are relatively inexpensive.
  • the system uses mass spectrometers and replaces the continuous gas chromatographs used to analyse gas from drilling mud. To facilitate this replacement, a total gas measurement should be taken.
  • the second output may be diverted from the mud pump to an identical degasser and this is run in a continuous mode. Using a very low dilution flow may be able to produce an adequate sample level for the total gas and H 2 S sensors.
  • pre-heating may be required in order to cause more gas to be emitted from the downstream degassing stage.
  • the mud heater can also be used to ensure that every batch of mud in an operation will have the same volume and be degassed at the same temperature.
  • the mud heater assembly 16 comprises an oil tank heater 40 and a heat exchanger 42 and is shown particularly in Fig. 3 .
  • the oil tank heater 40 comprises an electrically heated tube 40 and is suitable for zone 1 operation.
  • the heat exchanger 42 slides over the heated tube and has a spiral groove on the outer surface.
  • An external tube 44 or shell slides over the heat exchanger 42.
  • the outer tube 44 may be a suitable plastic or steel.
  • the heat exchanger is a close fit to the surface of the heated tube 40 and any air in the gaps is displaced with heat conductive oil.
  • the cover 44 is removable and is added as a close fit over the heat exchanger to define the mud passage along with an external surface of the heat exchanger which has a machined spiral groove.
  • a spiral flowpath is defined between the heater tube 40 and the outer tubular housing 44, for the returned drilling mud.
  • the heater is controlled from a control box 70 and heat from the electrically heated tube is transferred to the heat exchanger by direct metal surface contact or through a film of heat conductive oil.
  • the cold mud enters through an entry port, circulates along the spiral groove and exits through an exit port. In this configuration the heat from the exchanger is transferred to the mud.
  • An advantage of such embodiments is that they are particularly easy to clean and maintain, since the outer tubular housing 44 may be removed when off-line, and direct access to the spiral flowpath obtained. Thus blockages of drilling mud therein can easily be removed, for example by hosing down.
  • the electrically heated tube can be an off-the-shelf heater (such as those supplied by Exheat Limited of Norfolk United Kingdom) and not require additional certification itself for use in zone 1 operations.
  • This arrangement provides a low cost mud heater with a diameter preferably of around 150mm and height 1600mm resulting in a very small rig footprint.
  • the small footprint heater 16 can thus be located close to the mud pump 12 and the degasser 20, further shortening the mud lines and minimising blockage risks or process delays.
  • the heater is operated in a vertical orientation and it rests on a load cell. During normal operation the heater holds around 3 litres of mud and the load cell permits the operator to discriminate any changes in the weight of the mud to provide an adequate mud weight (SG) measurement which can be used within the system. This can also reduce the cost of the overall system since mud weight sensors can be very expensive and take up a lot of space .
  • the output from a load cell can also be used to detect gas inside the heater (if the heater weight drops unexpectedly) and this can be used to limit the power to the mud heater as part the safety system.
  • the complete mud heater assembly 16 is fully certified for zone 1 operations.
  • a housing 29 is made from sheet steel and welded to a base plate 23 where a drive motor 24 is located. In preferred embodiments the housing is also cone-shaped to minimise the internal volume.
  • a drive shaft 25 extends from the drive motor 24 through the base plate 23 and extends along the axis of the cone 22 and on into the fragmentation chamber area.
  • the degasser 20 in degassing mode, creates turbulence in the mud sample therein, aiming to remove the optimum quantity of gas entrained and dissolved in each batch; and retain this with the volume of air in the degasser until it is transferred to an analyser.
  • a top plate assembly is fitted to the degasser housing 29 with air seals.
  • the mud entry port 19 is attached to the top plate 18 such that the mud will drop into a mud fragmentation chamber 21 below.
  • spiral plate Inside the chamber 21 there is a spiral plate with slots and this will rotate with a cone 22.
  • the spiral plate is designed so that the mud will be fragmented as it passes through the slots and the centrifugal force will throw it onto the chamber wall.
  • the edge of the spiral plate will remove most of the mud but leave a mud smear on the chamber wall. The "wipe and smear" effect can release additional gas.
  • the fragmentation chamber may use a variety of different elements in order to assist in degassing the mud.
  • a spiral shaped mesh plate 26 is provided and attached to the drive shaft 25 and spins.
  • a bearing 6 remains stationary.
  • the drive shaft 25 is fitted with alternate rotating and non-rotating blades which lie within the fragmentation chamber 21 and in the case of the non-rotating blades, are secured thereon.
  • Another alternative is profiled blades which cause the mud to switch direction.
  • the cone 22 is also rotatably mounted on the drive shaft 25.
  • mud enters through the top of the fragmentation chamber 21 and impacts on the blades 26, 27 or slotted spiral plate and then drops into a well defined by the cone 22.
  • the proximity of the chamber wall 21 and the cone base minimises any mud splashing outwith the fragmentation chamber 21.
  • the mud which reaches the cone well will start to spin along with the cone 22 and the centrifugal force will cause it to rise up the angled cone's 22 wall as a sheet and fall over a castellated top edge 28 and into the degasser base.
  • studs 36 which are located in the outer wall of the cone and are used as part of the speed control system. They also spin the mud preventing debris build-up and encouraging the mud to exit through mud exit slot 37.
  • Four circulation holes 31 spaced around the top assembly allow gas to be drawn therethrough and move above the fragmentation assembly 26.
  • the combined effect of the fragmentation chamber 21 and the cone 22 provides a very good degassing performance.
  • the cone 22 also performs a secondary function as part of the sample sequence, as noted below.
  • the mud passing through the exit slot 37 leads into a chamber with a weir plate 38.
  • the main function of the weir 38 is to retain sufficient depth of mud within the degasser base to form an air seal and prevent loss of the gas and air inside degasser 10.
  • the weir 38 comprises two upstanding metal plates welded to the base and the cone walls adjacent to the ends of exit slot 37. The plates then form a passageway between the mud exit slot 37 and a mud discharge hole 39 in the base plate 23.
  • the weir 38 is fitted across the passageway with a height which maintains a suitable level of mud for the air seal.
  • the weir 38 can have a straight edge to provide a visible mud exit flow or a V-shaped slot with a level senor above it to provide an indicator of exit mud flow.
  • a series of lines 32, 33 are connected to the degasser 20 via separate ports in in a sample valve 17.
  • Line 32 is a dilution line and will, as described below, purge the degasser of gas after a gas sample has been extracted.
  • Line 33 connects the degasser to the mass spectrometer 50, and so delivers a gas pill thereto.
  • ports in sample valve 17 isolate lines 32 and 33 from the degasser head and connect them together. This allows a continuous flow of clean and optionally heated air to be circulated through lines 32, 33. This conditions the lines and minimises any moisture or contamination problems.
  • the valves are operated to isolate the sample and dilution lines from each other.
  • valves to lines. 32, 33 are closed and so any gas released from the mud builds up within the dilution air sealed inside the degasser 20 body.
  • the air or gas within the degasser is continuously circulated and mixed by the action of the moving components attached to the drive shaft 25. Gas removed from the sample cannot escape from the degasser body because the fluid in the "base” is held in the body by action of the weir 38 which provides a barrier. This process continues, gas builds up within the dilution air until the metering vessel 30 reaches the correct level wherein a sensor will switch the degasser and system more generally from a degassing mode to a sampling mode.
  • FIG. 5 A second embodiment of a degasser is shown in Fig. 5 . Like parts share common reference numerals except prefixed with a '1' and are not described further.
  • a fragmentation assembly 126 located on the main drive shaft 125 which rotates within the fragmentation chamber 121.
  • the details of the fragmentation assembly 126 are best shown in Figs. 6a - 6d although for clarity the fragmentation chamber 121 which surrounds the fragmentation assembly 126 and is shown in Fig. 5 , is not shown in Figs. 6a-6d .
  • the fragmentation assembly 126 has three thin horizontal plates 162 welded to the hollow drive shaft 125.
  • Two vertical metal strips 168 are welded to the edge of the rotating plates 152 and act as wipers which lift the mud off an inner wall of the fragmentation chamber 121 driving some back into the centre.
  • the metal strips/wipers 168 are normally spaced around 2mm from the inner wall of the fragmentation chamber 121. This still functions to wipe the wall, but can also mitigates heat build-up and also provides some tolerance, and reduces wear.
  • Each plate has a number of segments 164 cut out. Two of the segments 166 on each plate have one edge still attached to the plate 162 but extending out of the plane thereof, such that when the attached segments 164 are bent along the attached edges, they act as fan blades/vanes to drive air and mud through holes at the top of the fragmentation chamber 121 then down and out through a gap between the fragmentation chamber 121 and the cone inner wall 122.
  • the fan blades 166 induce circulation of any gas and air mix down through the chamber and this will then be drawn back though the circulation holes 131. This arrangement provides a homogenous gas in air mix within the degasser whilst it is running.
  • the top edge of the cone 122 does not have a castellated edge.
  • the mud passing through the exit slot 137 leads into a chamber with an adjustable weir pipe 138.
  • the weir area comprises three upstanding plates (not shown) with the weir pipe 138 as a screw fit into the base 123.
  • the height of the weir pipe 138 can be adjusted to suit different types of mud or conditions.
  • degassers disclosed herein are typically used in a batch sampling system as described herein, they may also be used to degas fluid in a continuous measurement operation.
  • the metering vessel 30 is located directly below the degasser's base plate and the following description applies to both Fig. 4 and Fig. 5 embodiments, unless otherwise noted.
  • the mud exiting over the degasser weir 38 shown in the Fig. 4 embodiment will drop through a hole 39 in the degasser base plate and into the metering vessel 30 via a narrow vertical chamber terminating near its base.
  • a further chamber with a level measuring sensor mounted at the top.
  • the combined effect of the two chambers provides a flat mud surface which is necessary for accurate ultrasonic level measurement.
  • the base of the metering vessel 30 has a slope leading down to a mud return pump 35.
  • the metering vessel 30 is emptied using a mud return pump 35 which drives the mud back to the ditch or the mud tanks.
  • the mud proceeds through the degasser 20, is degassed, and then proceeds into the metering vessel 30.
  • the degasser 20 is degassing, the mud builds up in the vessel 30 until it reaches a pre-determined level where a sensor (not shown) triggers the gas sample batch sequence as detailed below.
  • the metering vessel 30 meters a fixed volume of mud , independent of any minor changes in the mud flow rate, and therefore provides a quantitative gas sample.
  • an activator in the system switches from degassing mode to sampling mode, and a number of different events occur.
  • Ports in the sample valve block 17 isolate the dilution 32 and sample 33 lines from each other and connect the sample line 33 to the degasser's head.
  • a sample pump 52 then initiates the transfer of a volume of gas and air mixture as a sample pill from the degasser 10 to the mass spectrometer 50 in, for example, a logging cabin.
  • the drive shaft 25 stops or slows causing the continuous flow of mud into the degasser 20 to accumulate in the cone 22. Since this is either rotating slowly or not rotating, there is less centrifugal force to direct the mud over the castellations 28. Also the continued flow of mud into the cone 22 and replaces the volume of gas extracted through line 33, keeping the pressure inside the degasser 20 constant.
  • the mud return pump 35 operates during the gas sampling and purge period to empty the metering vessel 30 and return the mud back to a ditch or tank.
  • the system may be configured to also extract sufficient gas from the sample line 32 for an ISO tube 54 sample as well as the analyser buffer.
  • the ISO tube sample is a reference sample which can be used to take back onshore and check on much larger analysers in order to confirm the results from the onsite mass spectrometer 50 or other analyser.
  • the system switches from the sampling mode to a purge mode.
  • the degasser 20 restarts and the rotation displaces the mud which has collected inside the cone 22.
  • the dilution line 32 opens to allow the pressure which has built up therein to partially purge the degasser 20 and replace any mud volume displaced from the cone 22. After all the mud has been displaced from the cone 22 the dilution line 32 will continue to purge the degasser 20 for a period of time with the sample pump extracting the remains of the previous sample batch.
  • a clean air purge with a high flow to minimise the purge time and shorten the overall cycle time. This is timed to operate just as the cone 22 speeds up and when the volume of gas and air in the head is at the minimum level.
  • the degasser line 33 is closed and returned to degassing mode and so isolate the head.
  • the mud return pump 35 is stopped and a new degassing cycle commences.
  • the sampling and purge mode may take, together, around 40 seconds.
  • a small quantity of a known gas may be injected into the head of the degasser using a metering valve. This is detected at the analyser and provides a useful gas sample time or quantity bench mark.
  • the blowback functionality described above, to clear the suction head 14 is timed to act such that the mud used (which may have accumulated over time and not be representative of the mud going through the system at that present time) is the mud which is not analysed.
  • the mud used which may have accumulated over time and not be representative of the mud going through the system at that present time
  • the mud which is not analysed there is no effect from the periodic blowback operation on the portion of the mud sample which is used as the sample batch.
  • the system may also include the facility to monitor the quantitative amount of gas, referred to as a "total gas" facility 60.
  • a total gas facility 60 Such embodiments are particularly suitable where this system is to be used in place of a full chromatography service (gas analysis and total gas monitoring) in a mud logging cabin.
  • the system can operate with a twin diaphragm mud pump such as the dual pump 12 shown in Fig. 1a .
  • a twin diaphragm mud pump such as the dual pump 12 shown in Fig. 1a .
  • One mud stream exiting the pump will be directed to the batch degassing system as normal and the other mud stream will be directed to a degasser (not shown) which will operate in continuous mode.
  • the continuous degasser will be located immediately above the header tank or the mud ditch such that the mud exiting the continuous degasser will drop into the tank or ditch.
  • the continuous degasser is optionally connected via a sample line to an adjacent box housing a zone 1 total gas (IR) detector and an H2S detector.
  • IR total gas
  • H2S detector a sample pump or an air venturi within the box draws air from a clean location and through the degasser head where it will mix with the gas extracted from the continuous mud flow.
  • the gas and air mix passed through detectors inside the box and vent to a safe area.
  • the output from the detectors can be connected to the system field interface and the data link to the instrument panel.
  • a significant advantage of this arrangement will be a correlation between the gas which is analysed as a batch and the gas which is measured continuously since they both use mud from a common pump.
  • the output from the detectors can be connected to a local control panel to provide a standalone service in the zone 1 area.
  • the chromatographs may be used in lieu of the traditional gas chromatograph measurements, thus avoiding the requirement for two systems, the chromatographs also use substantial quantities of bottled hydrogen incurring space and logistic costs which can be avoided by utilising embodiments of a batch sampling mass spectrometer arrangement as described herein.
  • Embodiments of the present invention provide a mud circulation tank 17 which the main pump 12 can use to circulate mud through the system intermittently or continuously. This can help to clean out the circulation system and also prevents the mud gelling. Under normal circumstances when only the mud already in the system is to be circulated, the mud in the tank 17 is not accessed, and the system operates with a bypass valve at the tank 17 open. The mud circulation can also assist with pump priming if mud is lost at the inlet filter during drill connections.
  • a control and monitoring system is provided which operates with a dedicated process control package with a connection to a system computer 60.
  • the control function is used for process loops such as mud flow, mud temperature and mud volume. It also controls the gas sample sequencing routines.
  • Embodiments of the invention also have the ability to learn from operating experience and to develop a number of routines or set-ups for specific rig locations and mud conditions. For example special mud conditions, rig layouts or rig locations.
  • the monitoring function permits the operator to set normal operating and alarm levels for specific parameters or control loops. Any deviation outside the set limits can also be used as part of a dual level control system.
  • a schematic display is provided for an operator or others who need to monitor the system, with a simple view of the system integrity and failure modes. The display has a slave option to permit the operator to work in another location if the logging unit is unsuitable.
  • the monitoring function can be an important element for permitting single man operation with associated cost savings.
  • the monitoring system can also pass information such temperature, control loop status or standard operating routine numbers to the main computer 60 if it is necessary to annotate these on service logs.
  • Embodiments of the present invention are particularly useful because they can be used with a variety of different muds or drilling rig conditions. This provides a universal system compared to existing systems which tend to be bespoke depending in the type of mud or drilling rig with which they intend to be used.
  • the mud may be very cold and require more heating to provide a suitable sample for analysis.
  • Another option is to process a batch of the mud which is being pumped into the well (mud in). This can use a separate mud pump accessing the active mud tank with a circulation and return loop which connects through the main mud system loop. When a 'mud in' analysis is required a quantity of mud will be diverted from the loop and through the main loop during a drill connection break. The monitoring and control system will be able to handle the data as a separate function.
  • Such embodiments can easily compensate and increase the heating of the mud sample.
  • Another example is where the mud has more gas than average, and the sensor on the metering vessel can be set to trigger the sampling sequence when less mud has been measured. Accordingly certain embodiments benefit in that a single adaptable system may be provided and its use modified in order to suit the particular conditions or requirements of the user.
  • the analyser could be a gas chromatograph instead of a mass spectrometer. Nevertheless mass spectrometers are preferable.
  • mass spectrometers are preferable.
  • One advantage of a mass spectrometer compared to gas chromatograph is that they can discriminate inert gases such as helium as well as hydrocarbon gases.
  • mass spectrometers can also pick up the isotopes in the sample, thus providing even more data to the user.

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  • Engineering & Computer Science (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Geology (AREA)
  • Mining & Mineral Resources (AREA)
  • Physics & Mathematics (AREA)
  • Environmental & Geological Engineering (AREA)
  • Fluid Mechanics (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Mechanical Engineering (AREA)
  • Sampling And Sample Adjustment (AREA)
EP14161601.1A 2013-03-25 2014-03-25 System und Verfahren zur Analyse eines Bohrlochgas Withdrawn EP2796663A3 (de)

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GB201305411A GB201305411D0 (en) 2013-03-25 2013-03-25 System and method

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EP2796663A2 true EP2796663A2 (de) 2014-10-29
EP2796663A3 EP2796663A3 (de) 2016-06-15

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Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104841665A (zh) * 2015-03-16 2015-08-19 上海北裕分析仪器有限公司 气路清洗装置以及气路清洗方法
WO2019143362A1 (en) * 2018-01-19 2019-07-25 Halliburton Energy Services, Inc. Analysis of gas in drilling fluids
CN112903847A (zh) * 2021-01-21 2021-06-04 思凡(上海)石油设备有限公司 一种地层流体油气实时监测录井系统
US11480053B2 (en) 2019-02-12 2022-10-25 Halliburton Energy Services, Inc. Bias correction for a gas extractor and fluid sampling system
US11867682B2 (en) 2020-09-21 2024-01-09 Baker Hughes Oilfield Operations Llc System and method for determining natural hydrocarbon concentration utilizing isotope data
EP4306768A3 (de) * 2016-03-11 2024-07-03 Baker Hughes Holdings LLC Schlammpumpe und vakuumgasextraktionssystem

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Publication number Priority date Publication date Assignee Title
US4113452A (en) * 1975-07-31 1978-09-12 Kobe, Inc. Gas/liquid separator
US4365977A (en) * 1981-02-03 1982-12-28 Nl Industries, Inc. Drilling mud degasser
FR2856609B1 (fr) * 2003-06-27 2006-12-15 Geolog Spa Systeme de degazage d'un milieu liquide et d'analyse des gaz contenus dans le milieu liquide
JP2006078334A (ja) * 2004-09-09 2006-03-23 Mitsubishi Electric Plant Engineering Corp 液体中の溶解ガス量測定方法および溶解ガス量測定装置
IT1398065B1 (it) * 2010-02-08 2013-02-07 Geolog S P A Gas cromatografo da campo a ionizzazione di fiamma per l'analisi di idrocarburi gassosi pesanti.

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104841665A (zh) * 2015-03-16 2015-08-19 上海北裕分析仪器有限公司 气路清洗装置以及气路清洗方法
EP4306768A3 (de) * 2016-03-11 2024-07-03 Baker Hughes Holdings LLC Schlammpumpe und vakuumgasextraktionssystem
WO2019143362A1 (en) * 2018-01-19 2019-07-25 Halliburton Energy Services, Inc. Analysis of gas in drilling fluids
GB2582471A (en) * 2018-01-19 2020-09-23 Halliburton Energy Services Inc Analysis of gas in drilling fluids
GB2582471B (en) * 2018-01-19 2023-01-18 Halliburton Energy Services Inc Analysis of gas in drilling fluids
US11573215B2 (en) 2018-01-19 2023-02-07 Halliburton Energy Services, Inc. Analysis of gas in drilling fluids
US11480053B2 (en) 2019-02-12 2022-10-25 Halliburton Energy Services, Inc. Bias correction for a gas extractor and fluid sampling system
US11867682B2 (en) 2020-09-21 2024-01-09 Baker Hughes Oilfield Operations Llc System and method for determining natural hydrocarbon concentration utilizing isotope data
CN112903847A (zh) * 2021-01-21 2021-06-04 思凡(上海)石油设备有限公司 一种地层流体油气实时监测录井系统
CN112903847B (zh) * 2021-01-21 2022-08-26 思凡(上海)石油设备有限公司 一种地层流体油气实时监测录井系统

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