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EP-4532890-B1 - RIG-UP FOR PRESSURE CONTROL

EP4532890B1EP 4532890 B1EP4532890 B1EP 4532890B1EP-4532890-B1

Inventors

  • TØNDEL, Stian
  • RUSTEN, Torgeir

Dates

Publication Date
20260506
Application Date
20230525

Claims (20)

  1. A method for creating and verifying a thermite-based downhole well barrier (120) in a well (100), wherein the method comprises the steps of: - lowering a heat generating mixture (10) to a desired location (L) in the well (100); - igniting the heat generating mixture (10), thereby starting a heat generating process; characterized in that the method further comprises the steps of: - measuring a parameter (P(t)) representative of fluid pressure and/or fluid flow at an upper location (UL) of the well (100) as a function of time, at least from time of ignition (t0) of the heat generating mixture (10); - identifying a first peak area (PA1) of the measured parameter (P(t)); - determining that the integrity of the well barrier (120) is intact by comparing the first peak area (PA1) with a first peak area (EA1) of an expected parameter (E(t)).
  2. The method according to claim 1, wherein the method comprises the step of determining the expected parameter (E(t)) based on: - a generic expected parameter (GF(t)); and - specific well parameters (f1, f2, ....fn) for the well (100).
  3. The method according to claim 1 or 2, wherein the method comprises the steps of: - identifying a maximum point (P1max) within the first peak area (PA1) of the measured parameter (P(t)); - identifying a maximum point (E1max) within the first peak area (EA1) of the expected parameter (E(t)); - comparing the maximum point (P1max) within the first peak area (PA1) of the measured parameter (P(t)) with the maximum point (E1max) within the first peak area (EA1) of the expected parameter (E(t)).
  4. The method according to claim 3, wherein the step of identifying the maximum points (P1max, E1max) comprises: - identifying a point in time (TP1max) for the maximum point (P1max) within the first peak area (PA1) of the measured parameter (P(t)); - identifying a point in time (TE1max) for the maximum point (E1max) within the first peak area (EA1) of the expected parameter (E(t)); - comparing the point in time (TP1max) for the maximum point (P1max) within the first peak area (PA1) of the measured parameter (P(t)) with the point in time (TE1max) for the maximum point (E1max) within the first peak area (EA1) of the expected parameter (E(t)).
  5. The method according to claim 3 or 4, wherein the step of identifying the maximum points (P1max, E1max) comprises: - identifying an amplitude (AP1max) for the maximum point (P1max) within the first peak area (PA1) of the measured parameter (P(t)); - identifying an amplitude (AE1max) for the maximum point (E1max) within the first peak area (EA1) of the expected parameter (E(t)); - comparing the amplitude (AP1max) for the maximum point (P1max) within the first peak area (PA1) of the measured parameter (P(t)) with the amplitude (AE1max) for the maximum point (E1max) within the first peak area (EA1) of the expected parameter (E(t)).
  6. The method according to any one of the above, wherein the step of identifying the first peak area (PA1) of the measured parameter (P(t)) comprises: - identifying the first peak area (PA1) of the measured parameter (P(t)) within a first time interval (Δt1); and/or - identifying the first peak area (EA1) of the expected parameter (E(t)) within the first time interval (Δt1).
  7. The method according to claim 6, wherein the first time interval (Δt1) is 1 - 240 seconds measured from the time of ignition (t0), preferably 10 - 240 seconds measured from the time of ignition (t0), even more preferred between 10 - 120 seconds measured from the time of ignition (t0).
  8. The method according to any one of the above claims, wherein the method comprises the steps of: - identifying in initial maximum point (P0max) of the measured parameter (P(t)), wherein a point in time (TP0max) of the initial maximum point (P0max) is occurring prior to the point in time (TP1max) of the maximum point (PV1max) and wherein an amplitude (AP0max) of the initial maximum point (P0max) is lower than the amplitude (AP1max) of the maximum point (PV1max); - identifying an initial maximum point (E0max) of the expected parameter (E(t)), wherein a point in time (TE0max) of the initial maximum point (E0max) is occurring prior to the point in time (TE1max) of the maximum point (PE1max) and wherein an amplitude (AE0max) of the initial maximum point (E0max) is lower than the amplitude (AE1max) of the maximum point (PE1max); - comparing the amplitude (AP0max) and/or the point in time (TP0max) of the initial maximum point (P0max) of the measured parameter (P(t)) with the amplitude (AE0max) and/or the point in time (TP0max) for the maximum point (E0max) of the expected parameter (E(t)).
  9. The method according to any one of the above claims, wherein the method comprises the steps of: - identifying a second peak area (PA2) of the measured parameter (P(t)); - determining that the integrity of the well barrier (120) is intact by comparing the second peak area (PA2) with a second area (EA2) of the expected parameter (E(t)).
  10. The method according to claim 9, wherein the method comprises the steps of: - identifying a maximum point (P2max) within the second peak area (PA2) of the measured parameter (P(t)) as a point of time (TP2max) or an amplitude (AP2max); - comparing the point of time (TP2max) or the amplitude (AP2max) for the maximum point (P2max) with a time (TE2max) or an amplitude (AE2max) for a maximum point (E2max) of the second area (EA2) of the expected parameter (E(t)).
  11. The method according to any one of claims 9 - 10, wherein the step of identifying the second peak area (PA2) of the measured parameter (P(t)) comprises: - identifying the second peak area (PA2) of the measured parameter (P(t)) within a second time interval (Δt2); and/or - identifying the second peak area (EA2) of the expected parameter (E(t)) within the second time interval (Δt2).
  12. The method according to claim 11, wherein the second time interval (Δt2) is 0,5 - 4 hours, preferably 0,5 -2 hours, measured from the time of ignition.
  13. The method according to any of the preceding claims, wherein the method comprises the step of: - connecting a pressure-sealed tank (20) to a fluid outlet (130) of the well (100); - receiving well fluid (W) from the well (100) into the pressure-sealed tank (20) as a result of the heat generating process; - measuring the parameter (P(t)) inside the pressure-sealed tank (20).
  14. The method according to claim 13, wherein the method comprises the step of: - increasing the pressure inside the pressure-sealed tank (20) to a predetermined pressure above the topside ambient pressure before the time of ignition (t0).
  15. The method according to claim 14, wherein the method comprises the step of: - measuring a pressure reduction in the pressure-sealed tank (20) resulting from a fluid leakage in a period of time prior to the time of ignition (t0); - adjusting the parameter (P(t)) and/or the expected parameter (E(t)) according to the measured pressure reduction.
  16. The method according to claim 1, wherein the first peak area (PA1) of the measured parameter (P(t)) is a result of gas produced in the initial phase of the heat generating process.
  17. A system (1) for creating and verifying a thermite-based downhole well barrier (120) in a well (100), wherein the system comprises: - a heat generating mixture (10) located at a desired location (L) in the well (100); - an ignition device (11) for igniting the heat generating mixture (10) at the desired location (L) in the well (100); - a measuring device (50) arranged at an upper location (UL) of the well (100); - a user interface (60) connected to the measurement device (50) for providing an output of the measurements of the parameter (P(t)) to a user; characterized in that - the measuring device (50) is configured for measuring a parameter (P(t)) representative of pressure (Δp(t)) and/or fluid flow (ΔV(t)) as function of time, at least from time of ignition (t0) of the heat generating mixture (10); wherein the user interface (60) comprises a signal processing unit (62) configured to: - identify a first peak area (PA1) of the measured parameter (P(t)); - compare the first peak area (PA1) with an expected first peak area (EVP1); wherein it can be determined that the integrity of the well barrier (120) is intact based on the comparison of the first peak area (PA1) with the expected first peak area (EVP1).
  18. The system (1) according to claim 17, wherein the signal processing unit (62) is determining that the integrity of the well barrier (120) is intact based on the comparison of the first peak area (PA1) with the expected first peak area (EVP1).
  19. The system (1) according to claim 17 or 18, wherein the user interface (60) comprises a display (61) configured to display: - the measured parameter (P(t)); - the expected parameter (E(t)).
  20. The system (1) according to any one of claims 17-19, wherein the system comprises a pressure-sealed tank (20) for receiving the well fluid (W) from the well (100), the pressure-sealed tank (20) being fluidly connected to a fluid outlet (130) of the well (100).

Description

FIELD OF THE INVENTION The present invention relates to a method for creating and verifying a thermite-based downhole well barrier in a well. The present invention also relates to a system for creating and verifying a thermite-based downhole well barrier in a well. The present invention also relates to a method for providing a thermite-based downhole barrier in a well. BACKGROUND OF THE INVENTION To meet governmental requirements during plugging and abandonment (P&A) operations in a well, a deep-set barrier must be installed as close to the potential source of inflow as possible, covering all leak paths. A permanent well barrier shall extend across the full cross section area of the well, including all annuli, and seal both vertically and horizontally in the well. Normally cement is used for the purpose of P&A operations. Recently, an alternative method of performing P&A operations has been invented, using a heat generating mixture, e.g. a thermite mixture. Thermite is normally known as a pyrotechnic composition of a metal powder and a metal oxide. The metal powder and the metal oxide produce an exothermic oxidation-reduction reaction known as a thermite reaction. A number of metals can be the reducing agent, e.g. aluminium. If aluminium is the reducing agent, the reaction is called an aluminothermic reaction. Most of the varieties are not explosive but may create short bursts of extremely high temperatures focused on a very small area for a short period of time. The temperatures may reach as high as 3000°C. WO 2013/135583 discloses a method of abandoning a well by melting surrounding materials, such as pipes, cement and formation sand, the method comprising the steps of; providing an amount of a heat generating mixture, the amount being adapted to perform the desired operation, positioning the heat generating mixture at a desired position in the well, igniting the heat generating mixture, thereby melting the surrounding materials in the well. In traditional P&A operations, the barrier is formed by cement placed either inside casing and tubulars, or homogeneous across the entire cross section. In addition, cement is also positioned above the cross section interval inside of the tubulars at a distance of 30-50m. In cemented P&A operations the barrier may be tested by performing a pressure test of the well volume above the plug. However, this may not always be possible, for example where the well above the barrier is influenced by the P&A operation. In the thermite-based barrier formed by the method of WO 2013/135583, the heat generating mixture, e.g. the thermite mixture, when initiated, for example by ignition, will burn with a temperature of up to 3000°C and melt a great part of the proximate surrounding materials, with or without the addition of any additional metal or other meltable materials to the well. The surrounding materials may include any material normally present in the well, such as tubulars, e.g. casing, tubing and liner, cement, formation sand, etc. The heat from the ignited mixture will melt a sufficient amount of said materials. When the heat generating mixture has burnt out, the melted materials will solidify forming a sealing barrier comprising melted metal, cement, formation sand, etc. against the well formation. In some tests of the above method, the heat generating mixture was based on iron oxide and aluminium. It was found that a fluid path was formed through the casing above the sealing barrier. Hence, even if the method is creating a sealing barrier, a conventional pressure test of the sealing barrier cannot be used to verify the barrier, as pressurized fluid on the upper side of the barrier during the test will flow from the casing and out to the annulus outside of the casing. Moreover, while the prior art P&A operations based on cement allow the use of sensors for measuring various parameters at the location of the barrier during the operation, the temperature of the prior art P&A operations based on thermite does not allow such sensors at the location of the barrier during the operation, as sensors will be damaged by the heat. WO2020216649 describes a method of performing a permanent plugging and abandonment operation of a well by forming at least two barriers, the method comprising the steps of: - providing an amount of a heat generating mixture, - positioning the heat generating mixture at a first position in the well, the first position being at a cap rock of the well, - igniting the heat generating mixture thereby melting surrounding materials at the first position, - waiting a period of time, thereby allowing the melted materials to solidify into a reservoir sealing barrier which seals against a reservoir in the well, - forming a cap rock sealing barrier at a second position in the well by positioning a cap rock sealing material at the second position thereby sealing against the cap rock. After forming the cap rock sealing barrier, the method may comprise a verification proc