EP0572055B1 - Procédé de détection de fuites dans une colonne de forage - Google Patents

Procédé de détection de fuites dans une colonne de forage Download PDF

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Publication number
EP0572055B1
EP0572055B1 EP93201208A EP93201208A EP0572055B1 EP 0572055 B1 EP0572055 B1 EP 0572055B1 EP 93201208 A EP93201208 A EP 93201208A EP 93201208 A EP93201208 A EP 93201208A EP 0572055 B1 EP0572055 B1 EP 0572055B1
Authority
EP
European Patent Office
Prior art keywords
drillstring
washout
trend
determining
hydraulic coefficient
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.)
Expired - Lifetime
Application number
EP93201208A
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German (de)
English (en)
Other versions
EP0572055A1 (fr
Inventor
Mohamed Damak
Dominic Patrick Joseph Mccann
David Brian White
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Services Petroliers Schlumberger SA
Sedco Forex Technology Inc
Original Assignee
Services Petroliers Schlumberger SA
Sedco Forex Technology Inc
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Publication date
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Publication of EP0572055A1 publication Critical patent/EP0572055A1/fr
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Publication of EP0572055B1 publication Critical patent/EP0572055B1/fr
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Classifications

    • 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
    • E21B44/00—Automatic control systems specially adapted for drilling operations, i.e. self-operating systems which function to carry out or modify a drilling operation without intervention of a human operator, e.g. computer-controlled drilling systems; Systems specially adapted for monitoring a plurality of drilling variables or conditions
    • 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
    • E21B21/08—Controlling or monitoring pressure or flow of drilling fluid, e.g. automatic filling of boreholes, automatic control of bottom pressure

Definitions

  • the present invention relates to a method for detecting washouts in drillstrings being used to drill a well such as a hydrocarbon well or a geothermal well.
  • the drillstring used comprises a plurality of pipes linked end to end and having a drill bit located at the lower end thereof.
  • a drilling fluid known as drilling mud
  • Drilling mud contains finely divided solid material which gives the circulating mud abrasive properties.
  • a washout If this is not detected, the weakness in the drillstring at that point can cause the string to break due to the torque experienced by the string. This is known as a twist-off and is costly in both time and equipment as it will involve a fishing operation to retrieve the lost end of the drill string before drilling can recommence.
  • Washouts can be detected by monitoring the flow of drilling mud in the drillstring.
  • the presence of a washout will change the way in which the mud flows in the drillstring and so continuous monitoring of the flow will allow detection.
  • the number of pipes in the drillstring changes in a relatively short time also the flow through the drillstring varies considerably from connection to connection which makes washout detection more difficult.
  • a system is disclosed for the monitoring of standpipe pressure. The known system raises an alarm when anomalous pressures occur. It includes means for signalling a drill pipe washout if the standpipe pressured decreases and the all mud flow rates increase.
  • a method of detecting a drillstring washout during an operation involving the addition or removal of pipes from the drillstring comprising:
  • the flow rate of drilling fluid in the drill string and the standpipe pressure are monitored while the operation in question takes place.
  • the expected hydration coefficient is calculated from a model obtained from previous connections or operations. This value is compared with the actual value of the hydraulic coefficient measured for the connection.
  • the step b) comprises determining the trend in the development of k and comparing the trend with that calculated for the series.
  • the determined values of k are included in the series provided that a washout has not been detected during that operation.
  • An alternative to determining trends is to estimate a value of k from the series for a given pipe length and comparing this with the current value.
  • a typical land drilling rig which comprises a mast or derrick 10 from which a drill string 12 is supported by means of a hook 13 mounted on a travelling block 15, the altitude of which can be adjusted by means of a cable 14.
  • the drill string is formed from a number of drill pipes or drill collars 16 connected end to end and extends into the well, a drill bit 18 being mounted at its lower end.
  • Drilling fluid is circulated from a pit 20 to the top of the drill string 12 via a standpipe 22 and down through the inside of the pipes and collars to the bit 18 where it exits through nozzles and returns to the surface in the annulus formed between the drill string and the well wall.
  • the fluid On leaving the well at the surface, the fluid is returned to the pit and is recirculated into the well.
  • pipes or collars are added to or removed from the drill string in order to change the overall length.
  • the travelling block In drilling ahead, the travelling block is lowered by slackening off the cable such that at least some of the weight of the drill string is borne by the bit and the string is rotated so as to allow the bit to drill into the formation.
  • Sensors are provided on the rig to measure flow rate of fluid entering the string and/or leaving the annulus at the surface, the pressure of fluid in the stand pipe, the altitude of the travelling block, the load on the cable and the rate of rotation of the drill string. Signals from these sensors can be processed to provide, inter alia, an indication of string length, rate of drill bit penetration when drilling, occurrence of fluid influxes and other events when rig operations are taking place.
  • the present invention is particularly applicable to situations when the drill string is being rotated and the length is being changed fairly rapidly such as might occur in reaming operations, tripping or stabbing.
  • the hydraulic coefficient k is a constant which depends on the drill string geometry and on the density of the drilling fluid. Within one circulation period, the drill string length remains constant and so any trend in the hydraulic coefficient is an indication of an abnormal event, for example a decrease in k would indicate a washout.
  • a typical algorithm for detecting anomalies is the Hinkley method (Biometrica 42,6, pp1897-1908, 1971).
  • the detection of a given number of events (typically two or three) within a given time period is used to generate an alarm.
  • the time period might typically be set at 15 minutes which is not suitable for operations such as reaming where the time between connections can be significantly less than this.
  • the hydraulic coefficient calculated for the previous connection or connections is stored and the history of the behaviour of the hydraulic coefficient determined to build up a model of the hydraulic coefficient against depth. The trend from previous operations can also be stored.
  • the hydraulic coefficient for a given stand is compared with the model and trend and the detection algorithm applied to detect anomalies.
  • the proposed method does not look only at the current circulation period, but keeps the history of the hydraulic coefficient behaviour from circulation to circulation during the current reaming operation. It also keeps the trend from the last reaming operation provided that the mud and the BHA have not changed.
  • the fractional change in the hydraulic coefficient k is compared with an empirically derived coefficient. Typically the following relationship is used to confirm that a point can be added to the model: k n +1 - k n k n ⁇ 2.6
  • the algorithm calculates, for each stand, the hydraulic coefficient value, from the measured flow rate and stand pipe pressure, and builds a linear model of hydraulic coefficient against string length typically using a least squares method.
  • the model is updated as every stand is pulled or added provided a washout has not been detected.
  • the algorithm compares the hydraulic coefficient of the current stand with the expected value estimated by the linear model built from the previous stands in the same reaming operation. If the measured value is lower than the estimated one by a certain amount typically 1%, a washout is indicated.
  • Figure 2 shows three logs collected whilst circulating and pulling the drillstring out of hole, obtained from the North Sea.
  • the hook load and the stand pipe pressure logs show that a twist off occurred at about 24717 s.
  • the flow channel shows that the circulation periods are often very short (about 6 minutes). Also, that the flow varies from stand to stand between 3800 1/min and 4050/min. As a result it is difficult to detect a washout by simply observing the stand pipe pressure for each connection or even over a number of connections, since it varies from stand to stand considerably because it is proportional to the flow rate squared and the trend is hidden in this variation.
  • Figure 4 shows how the proposed algorithm detects the washout whilst pulling the forth stand, that is, four connections before the twist off. It does this by comparing the calculated trend with that from the previous reaming operation.
  • Figure 5 shows reaming data in a normal operation (without any washout). It can be seen that the hydraulic coefficient varies linearly with the string length. In this example, all of the measured data fall within the expected range of the model and therefore no alarms are raised.
  • the calculated trend which is the gradient from the least square calculation, is compared to the one from the last remaining operation model. If actual trend >1.65* last trend, a washout alarm is raised.
  • the coefficient 1.65 has been empirically defined by studying sets of field data.
  • Figure 5 shows a normal evolution of the hydraulic coefficient k during reaming against depth. It can be seen that the hydraulic coefficient varies linearly with the string length and k drops as the stands are pulled. The linear curve models the trend of the hydraulic coefficient from stand to stand. The range of expected values is about ⁇ 1% of the estimated value ( ⁇ 3*standard error of estimate).
  • Figure 5 shows how, once the linear model is built from the previous stand, the algorithm deduces an estimated hydraulic coefficient (+) for the current stand and compares it with the measured value (*). In this case the measures data falls within the expected range and therefore no alarm is raised
  • Figure 4 shows how the new algorithm detects the washout whilst pulling the fourth stand, that is four connections before the twist off. It does this by comparing the calculated trend with that from the previous reaming operation.
  • Figure 6 shows running in hole data where the hydraulic coefficient increase as stands are added. At the last point, the pressure is higher than expected because the MWD is switched on. The algorithm checks if the MWD is transmitting data by checking the RPM (Rotation Per Minute) value. The RPM is zero when the MWD is transmitting data. The algorithm currently ignores this point and does not include it in the model.
  • RPM Radiotation Per Minute

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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)
  • Earth Drilling (AREA)
  • Examining Or Testing Airtightness (AREA)

Claims (9)

  1. Procédé de détection d'une fuite dans une colonne de forage lors d'une opération impliquant l'adjonction ou l'enlèvement de conduits dans la colonne de forage, comprenant :
    a) - l'exécution au moins une fois de ladite opération et la détermination du coefficient hydraulique k à partir de la relation P = kQa, où Q est le débit, P est la pression dans la colonne montante et a est l'exposant du débit (« flow exponent »), de chaque conduit ajouté ou enlevé, de façon à en déduire une série de valeurs indiquant l'évolution (« development ») de k pour lesdites opérations,
    b) - la déduction à partir de ladite série d'une valeur attendue de k pour une opération ultérieure, et
    c) - lors de ladite opération ultérieure, la détermination de k et la comparaison de la valeur déterminée avec la valeur attendue de k, une fuite dans une colonne de forage étant détectée lorsque la valeur déterminée de k est très (« substantially ») inférieure à ladite valeur attendue de k.
  2. Procédé selon la revendication 1, dans lequel le débit du liquide de forage dans la colonne de forage et la pression dans la colonne montante sont contrôlés (« monitored »).
  3. Procédé selon l'une quelconque des revendications précédentes, dans lequel les valeurs déterminées de k sont inclues dans les séries à condition qu'une fuite n'ait pas été détectée pendant cette opération.
  4. Procédé selon l'une quelconque des revendications précédentes, dans lequel pour chaque adjonction ou enlèvement d'un conduit, le coefficient hydraulique attendu est calculé à partir d'un modèle obtenu à partir d'opérations ou connections précédentes et est comparé avec la valeur réelle mesurée du coefficient hydraulique pour cette connection dans le but d'observer la formation, l'évolution (« development ») d'anomalies.
  5. Procédé selon la revendication 4, dans lequel l'étape c) comprend la détermination de la tendance (« trend ») dans l'évolution de k, et la comparaison de ladite tendance avec celle calculée pour les séries.
  6. Procédé selon l'une quelconque des revendications 1 à 4, dans lequel la tendance calculée du coefficient hydraulique est comparée à celle enregistrée lors d'une précédente opération du même type.
  7. Procédé selon l'une quelconque des revendications précédentes, dans lequel l'opération comprend une opération d'alésage (« reaming »).
  8. Procédé selon l'une quelconque des revendications précédentes, comprenant de plus une étape de détermination du fait qu'un système MWD est en fonctionnement et de non-prise en compte d'une anomalie de pression lorsque ledit système est en fonctionnement.
  9. Procédé selon la revendication 8, dans lequel l'étape de détermination du fait qu'un système MWD est en fonctionnement comprend la mesure du taux de rotation de la colonne de forage et la détection du moment où le taux de rotation indique que le système MWD est en fonctionnement.
EP93201208A 1992-05-23 1993-04-27 Procédé de détection de fuites dans une colonne de forage Expired - Lifetime EP0572055B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB9211048A GB2267300B (en) 1992-05-23 1992-05-23 Method for detecting drillstring washouts
GB9211048 1992-05-23

Publications (2)

Publication Number Publication Date
EP0572055A1 EP0572055A1 (fr) 1993-12-01
EP0572055B1 true EP0572055B1 (fr) 1997-03-26

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EP93201208A Expired - Lifetime EP0572055B1 (fr) 1992-05-23 1993-04-27 Procédé de détection de fuites dans une colonne de forage

Country Status (5)

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EP (1) EP0572055B1 (fr)
CA (1) CA2095583C (fr)
DE (1) DE69309149D1 (fr)
GB (1) GB2267300B (fr)
NO (1) NO304710B1 (fr)

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1637695A1 (fr) * 2000-09-22 2006-03-22 Weatherford/Lamb, Inc. Méthode et appareil pour la monitorisation et le contrôle à distance.
US7694558B2 (en) * 2008-02-11 2010-04-13 Baker Hughes Incorporated Downhole washout detection system and method
US8170800B2 (en) 2009-03-16 2012-05-01 Verdande Technology As Method and system for monitoring a drilling operation
US8381838B2 (en) 2009-12-31 2013-02-26 Pason Systems Corp. System and apparatus for directing the drilling of a well
EP2864576A4 (fr) * 2012-06-22 2016-07-27 Services Petroliers Schlumberger Détection d'un événement de fuite de train de tiges de forage
US11313220B1 (en) 2021-02-17 2022-04-26 Saudi Arabian Oil Company Methods for identifying drill string washouts during wellbore drilling

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3646808A (en) * 1970-08-28 1972-03-07 Loren W Leonard Method for automatically monitoring and servicing the drilling fluid condition in a well bore
US4188624A (en) * 1978-06-30 1980-02-12 Nl Industries, Inc. Method and apparatus for monitoring fluid flow through a drill string
US4346594A (en) * 1980-11-14 1982-08-31 Owings Allen J Method for locating the depth of a drill string washout or lost circulation zone
US4430892A (en) * 1981-11-02 1984-02-14 Owings Allen J Pressure loss identifying apparatus and method for a drilling mud system
US4941951A (en) * 1989-02-27 1990-07-17 Anadrill, Inc. Method for improving a drilling process by characterizing the hydraulics of the drilling system

Also Published As

Publication number Publication date
GB2267300B (en) 1995-08-02
NO304710B1 (no) 1999-02-01
NO931863D0 (no) 1993-05-21
EP0572055A1 (fr) 1993-12-01
GB2267300A (en) 1993-12-01
CA2095583C (fr) 2004-08-10
GB9211048D0 (en) 1992-07-08
DE69309149D1 (de) 1997-04-30
CA2095583A1 (fr) 1993-11-24
NO931863L (no) 1993-11-24

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