Multi-part dissolvable flow-plug, well system in subterranean formation comprising said plug, method for removing said plug, and use of said plug

Abstract

The present invention relates to a multi-part dissolvable flow-plug, a well system in subterranean formation comprising said multi-part dissolvable flow-plug, a method for removing said multi-part dissolvable flow-plug, and use of said multi-part dissolvable flow-plug, wherein the parts of the multi-part dissolvable flow-plug comprises parts which are soluble in an aqueous solvent.

Description

[0001] MULTI-PART DISSOLVABLE FLOW-PLUG, WELL SYSTEM IN SUBTERRANEAN FORMATION COMPRISING SAID PLUG, METHOD FOR REMOVING SAID PLUG, AND USE OF SAID PLUG

[0002] The present invention relates to a multi-part dissolvable flow-plug, a well system in subterranean formation comprising said multi-part dissolvable flow-plug, a method for removing said multi-part dissolvable flow-plug, and use of said multi-part dissolvable flow-plug.

[0003] A wellbore is often used to harvest desired fluids and / or gasses, such as water and hydrocarbons (oil and natural gas), from wells which are located underneath the earth surface. For a properly functioning wellbore several tools are inserted into the wellbore to enable the extraction of said fluids and / or gasses. The insertion of the tools, for example liners, into the wellbore requires a closed inner system of the tools. In other words, the liquids and gasses should not leave the well at inserting the liners into the wells. Therefore, openings in the tools (liners) need to be closed with temporarily. For example, a flow-plug may be used to block a flow path to prevent the ingress of fluids into the completion.

[0004] The flow-plug may generally be described as temporary, as it may not be desired to permanently plug the flow path throughout the useful life of the completion. Some temporary flowplugs may function until removal is desired, at which point an affirmative step may be taken to remove the flow-plug. Alternatively, some temporary flow-plugs may be designed such that they fail when desired without the need for an affirmative step after their useful life has passed.

[0005] Such flow-plug may be removed with a specific solvent. However, control over dissolving the flow-plug is limited for an operator as the flow-plug is only able to be removed through contact with a sufficient amount of the specific solvent. Furthermore, dissolving conventional flow-plugs in a suitable solvent results in a solvent which will take the path of least resistance. Therefore, the first flow-plug to be dissolved will consequently be the location at which most of the subsequently pumped solvent flows through. As such, dissolution of any remaining flow-plugs may not occur or may occur at a rate which reduces the productivity of the well.

[0006] These problems prevent an efficient and effective use of a new wellbore. This problem is even bigger when multiple flow-plugs are used for completion of the wellbore.

[0007] The present invention aims at obviating or at least reducing the aforementioned problems and to enable efficient and effective completion of a wellbore. Furthermore, it is an object of the invention to make the process of building an oil or gas production well or water well or water injector or gas injector easier and / or less costly and / or faster.

[0008] This objective is achieved with a multi-part dissolvable flow-plug comprising at least two parts, wherein the at least two parts comprising:a first part made of an aqueous dissolvable material comprising an aqueous dissolvable metal; and

[0009] a second part made of a polyester which is soluble in an aqueous solvent, wherein the at least two parts are assembled adjacent to each other.

[0010] The multi-part dissolvable flow-plug may be assembled in a liner used for opening a well with a wellbore.

[0011] After placement of the liner comprising the plug according to the invention, the flow-plug according to the invention may at least partially degrade and / or dissolve to at least partially open the inflow / outflow openings, so that oil, gas or water may flow therethrough. The degrading and / or dissolving of the flow-plug according to the invention may soften it, so that it deforms and is removed from the inflow / outflow opening due to a pressure difference across the inflow / outflow opening. The liner may then, being in its use configuration, be used for production or injection.

[0012] The at least one inflow / outflow opening may be an inflow opening, especially when the liner is used in a production well, or an outflow opening, especially when the liner is used in an injector, or both when the liner is used to produce and inject at different times. The liner may further comprise one or more end openings at its longitudinal ends, used to connect the flow space of several liners to each other. These end openings are distinct from the inflow / outflow openings in the circumferential wall.

[0013] It is noted that said inflow / outflow opening may be any type of opening and / or may be arranged at any suitable location. For example, the inflow / outflow opening may be arranged in the circumferential wall directly and may provide a trough flow opening between the flow space of the liner and the external environment outside of the liner. Alternatively, or additionally, the inflow / outflow opening may be arranged in an ICD or OCD that is in medium through flow connection with a through flow opening in the circumferential wall of the liner, such that the wall connects to this type of inflow / outflow opening. The inflow / outflow opening may be defined at any location of a medium through flow path between the hollow space of the liner and the external environment outside of the liner.

[0014] It is further noted that the multi-part flow-plug may be arranged at any suitable location of a medium through flow path between the hollow space of the liner and the external environment outside of the liner and / or in any suitable inflow / outflow opening that is arranged in or connects to the circumferential wall, as long as it blocks fluid flow to pass from the flow space to the exterior environment of the liner or vice versa when it is in place.

[0015] It is further noted that the multi-part flow-plug may fill up the entire length of the inflow / outflow opening or only a part of the length thereof.

[0016] The material may be degradable in that it breaks down, falls apart into smaller pieces, or dissolves when subjected to a degrader / aqueous solvent. The degrader is practically a fluid, such asan aqueous solvent, preferably a liquid. The material may be dissolvable in that it dissolves either partly or completely in a dissolver fluid or liquid, thereby forming a solution. It is sufficient for the invention if the material being degradable and / or dissolvable causes the plug to at least partly open the inflow / outflow opening, in order to allow liquid / gas to flow through the inflow / outflow opening. Consequently the terms degradable and dissolvable are not to be understood in a limited fashion.

[0017] Letting the plug degrade or dissolve may include waiting a certain period of time while the plug is subjected to a degrader / dissolver fluid. The degrader / dissolver fluid may be introduced by for instance pumping, or may be present in the bore hole already, or both.

[0018] An advantage of the multi-part dissolvable flow-plug according to the invention is that said plug comprises multiple parts, wherein said multiple parts are soluble in different solvents. As a result, using multiple flow-plugs according to the invention in, for example a liner, can be dissolved evenly and in a controlled manner. Therefore, a liner for example, may be opened evenly such that substantially the full capacity of said liner can be used.

[0019] Furthermore, the first part of the multi-part flow-plug according to the invention is made of an aqueous dissolvable material and the second part is made of polyester which is soluble in an aqueous solvent. Preferably, the first part and the second part are at least partly soluble in different aqueous solvents.

[0020] In addition, the multi-part flow-plug according to the invention reduces or even prevents the flow-plug from severe damage during running in hole as the individual parts of the flow-plug are at least partly protected by other parts of the flow-plug. Therefore, undesired breakthrough of the plugs is prevented.

[0021] A further advantage of the multi-part dissolvable flow-plug according to the invention is that said plug is enabled to withstand a pressure of more than 150 bar, preferably more than 250 bar, and up to 500 bar.

[0022] The combination of different materials provides a flow-plugs which dissolve at a similar rate and which could withstand the pressure from the well sufficiently. As a result, the flow-plugs, used in a liner, open the inflow / outflow opening substantially simultaneously.

[0023] Furthermore, the different materials of the multi-part dissolvable flow-plug may provide a controlled dissolution with the different and displaced(circulated) fluids inside and / or outside a liner.

[0024] Yet another advantage of the multi-part dissolvable flow-plug according to the invention is that said plugs enable to clean a wellbore after all plugs are dissolved in an efficient and effective manner. As a result, the efficiency of a wellbore is increased compared to a wellbore including a liner with conventional plugs.

[0025] In a presently preferred embodiment according to the invention, the multi-part dissolvable flow-plug according to the invention comprises at least three parts, wherein the third part of the at least three parts may be made of an aqueous dissolvable material comprising an aqueous dissolvablemetal, and wherein the second part is at least on one side delineated by the first part and on another side delineated by the third part.

[0026] A multi-part dissolvable flow-plug therefore comprises in the following order, a first part, a second part, and a third part, wherein the first part is adjacent to and at least partly delineated by the second part, and the second part is adjacent to and at least partly delineated by the third part.

[0027] It was found that providing a flow-plug comprising at least three parts provide an even better control over the solubility.

[0028] In a preferred embodiment, the first part and the third part are dissolvable in different aqueous solvents. In addition, the second part is partly dissolvable in the aqueous solvent used to dissolve the first part and partly dissolvable in the aqueous solvent used to dissolve the third part.

[0029] In a further presently preferred embodiment according to the invention, the first part made of an aqueous dissolvable material dissolves in an aqueous solvent having a pH above 7, and wherein the third part made of an aqueous dissolvable material comprising an aqueous dissolvable metal which dissolves in an aqueous solvent having a pH below 7.

[0030] An advantage of providing materials for the first part, second part and / or third part which dissolve in an aqueous solvent with different pH is that the rate of dissolving the multi-stage dissolvable flow-plug can be defined and tuned. In other words, by changing the pH of the aqueous solvent, different parts of the flow-plug may dissolve.

[0031] For example, an aqueous solvent having a pH above 7 is a brine solution and an aqueous solvent having a pH below 7 is a hydrogen chloride solution.

[0032] In a further presently preferred embodiment according to the invention, the polyester has a melting temperature of at least 130 °C, preferably of at least 150 °C, more preferably of at least 170 °C, most preferably of at least 200 °C.

[0033] It was found that a polyester comprising a melting temperature of at least 130 °C, preferably of at least 150 °C, more preferably of at least 170 °C, most preferably of at least 200 °C enables an efficient and effective multi-part dissolvable flow-plug. Furthermore, using a polyester having a low melting temperature may reduce the temperature of the solvent used to dissolve the multi-part dissolvable flow-plug according to the invention.

[0034] In a further presently preferred embodiment according to the invention, the polyester is poly(glycolic acid) and / or poly lactic acid.

[0035] An advantage of poly (glycolic acid) and / or poly lactic acid is that said polymers may readily dissolve in aqueous solvents comprising an organic solvent. Said organic solvents are for example alcohols such as methanol, ethanol, isopropanol, or ketones such as acetone. As a result, the degree and rate of dissolving may be tuned by an operator. Preferably, said organic solvent is one or more selected from the group of glycerol, acetone, methanol, ethanol, ethylene, glycol, isopropanol, other suitable solvents and / or mixtures thereof.In addition, poly(glycolic acid) and / or polylactic acid have the advantage that it may be sufficiently strong and stiff, and that it is biodegradable. In particular degrading poly(glycolic acid) and / or poly lactic acid may leave no or little undegraded solids after sufficient time Furthermore, using poly(glycolic acid) and / or polylactic acid as polyester enables to provide an efficient and effective multi-part dissolvable flow-plug.

[0036] In a further presently preferred embodiment according to the invention, the aqueous dissolvable metal of the aqueous dissolvable material, preferably the aqueous dissolvable material from the first part and / or from the third part, comprises one or more metal selected from the group of magnesium, aluminium, zinc, iron, copper, manganese, nickel, calcium, gadolinium, yttrium, preferably one or more selected from the group of magnesium, aluminium, zinc, iron, copper, nickel, calcium, gadolinium, yttrium.

[0037] It is noted that the aqueous dissolvable material of the first part and the aqueous dissolvable material of the third part may comprise one or more metal selected from the abovementioned group.

[0038] An advantage of the aqueous dissolvable metal of the aqueous dissolvable material comprising one or more metal selected from the group of magnesium, aluminium, zinc, iron, tin, copper, manganese, nickel, calcium, gadolinium, yttrium is that said metal ions can withstand the environmental influences when a liner is provided to a wellbore and can dissolve in aqueous solvents.

[0039] In a further presently preferred embodiment according to the invention, the aqueous dissolvable material comprising an aqueous dissolvable metal, preferably the aqueous dissolvable material from the first part and / or from the third part, may be an alloy.

[0040] It was found that the aqueous dissolvable material comprising an aqueous dissolvable metal being an alloy formed by one or more selected from the group of magnesium, aluminium, zinc, iron, tin, copper, manganese, nickel, calcium, gadolinium, yttrium provides an efficient and effective multi-part dissolvable flow-plug.

[0041] In a further presently preferred embodiment according to the invention, the aqueous dissolvable material comprising an aqueous dissolvable metal, preferably the aqueous dissolvable material from the first part and / or from the third part, further comprises a depassivating agent, wherein the depassivating agent may be one or more selected from the group of gallium, indium, tin.

[0042] An advantage of the depassivating agent is that the strength of the multi-part dissolvable flowplug is increased. Such increase in strength is in particular beneficial when a liner comprising said flow-plug is exposed to high pressures. For example, pressures of more than 200 bar, preferably more than 250 bar.

[0043] In a further presently preferred embodiment according to the invention, the aqueous dissolvable material of the first part and the aqueous dissolvable material of the third part are different compositions.It was found that a multi-part dissolvable flow-plug wherein the aqueous dissolvable material of the first part and the aqueous dissolvable material of the third part are different compositions provides an efficient and effective flow-plug. Unblocking of the outflow and / or inflow using said flow-plug provides can be in an even more controlled manner.

[0044] In a further presently preferred embodiment, the second part is made of poly(glycolic acid) and / or polylactic acid, wherein the first part and the third part are made of different materials, and wherein the first part comprises a depassivating agent. Preferably, the second part and / or third part also comprises a depassivating agent.

[0045] In a preferred embodiment, the depassivating agent of the first part, the second part, and / or the third part are individually selected from the group of gallium, indium, tin.

[0046] An advantage of a plug comprising three parts, wherein the second part is made of poly(glycolic acid) and / or polylactic acid, wherein the first part and the third part are made of different materials, and wherein the first part comprises a depassivating agent is that an efficient and effective partial degradation and / or dissolving to at least partially open the inflow / outflow openings, so that oil, gas or water may flow therethrough is achieved. The degrading and / or dissolving of the flow-plug according to the invention may soften it, so that it deforms and is removed from the inflow / outflow opening due to a pressure difference across the inflow / outflow opening. The liner may then, being in its use configuration, be used for production or injection.

[0047] In a further preferred embodiment, the multi-part flow plug comprises at least three parts, wherein the at least three parts comprising:

[0048] a first part made of an aqueous dissolvable material comprising an aqueous dissolvable metal;

[0049] a second part made of a polyester which is soluble in an aqueous solvent;

[0050] a third part made of an aqueous dissolvable material comprising an aqueous dissolvable metal,

[0051] wherein the second part is at least on one side delineated by the first part and on another side delineated by the third part.

[0052] Preferably, the second part is delineated by the first part and third part on opposite sides. The invention also relates to a well system in subterranean formation, comprising a multi-part dissolvable flow-plug according to the invention and a nozzle, wherein the nozzle comprises a flow path which provides fluid communication from one side of the nozzle to another side of the nozzle, and wherein the multi-part dissolvable flow-plug is assembled within the nozzle such that the flow path is blocked prior to use.

[0053] The well system in subterranean formation according to the invention provides the same or similar effects and advantages as those described for the multi-part dissolvable flow-plug according to the invention.An advantage of the well system according to the invention is that the amount of malfunctions is reduced compared to conventional systems. This reduction is due to the evenly and controlled removal of the multi-part dissolvable flow-plug.

[0054] In a presently preferred embodiment according to the invention, the well system further comprises multiple combinations of the multi-part dissolvable flow-plug and the nozzle.

[0055] In a further presently preferred embodiment according to the invention, the well system further comprises a liner comprising an outer wall, wherein the outer wall is configured to hold one or more nozzles.

[0056] The invention also relates to a method for removing a multi-part dissolvable flow-plug according to the invention from a well system according to the invention, comprising the steps of:

[0057] providing an aqueous solvent to the inside and / or outside of the well system; and circulating the solvent inside and / or outside the well system to dissolve at least a portion of the at least two parts facing the inside and / or outside of the well system.

[0058] The method for removing a multi-part dissolvable flow-plug according to the invention provides the same or similar effects and advantages as those described for the multi-part dissolvable flow-plug according to the invention and well system in subterranean formation according to the invention.

[0059] An advantage of the method according to the invention is that each part of the multi-part dissolvable flow-plug dissolves with a rate in the range of 0.01 mm h1to 2 mm h1when the suitable solvent is selected.

[0060] In a preferred embodiment, the step of providing an aqueous solvent to the inside and / or outside of the well system comprises the step of providing an aqueous solvent with a pH below 7 to the inside and / or outside of the well system.

[0061] An advantage of providing an aqueous solvent with a pH below 7 to the inside and / or outside of the well system is that efficient and effective dissolving of the at least a portion of the at least two parts of the multi-part dissolvable flow-plug according to the invention facing the inside and / or outside of the well system is achieved.

[0062] In a presently preferred embodiment according to the invention, the method further comprises the step of amending and / or changing the aqueous solvent.

[0063] The step of amending and / or changing the aqueous solvent may include the change in composition of the aqueous solvent and / or the change in pH of the aqueous solvent. For example, the pH may be increased during the step of circulating the solvent inside and / or outside the well system.

[0064] In a further presently preferred embodiment according to the invention, the aqueous solvent comprises one or more salts.In a further preferred embodiment the aqueous solvents further comprise one or more selected from the group of glycerol, acetone, methanol, ethanol, ethylene, glycol, isopropanol, other suitable solvents. These solvents may be readily available.

[0065] In a preferred embodiment, the aqueous solvent having a pH below 7 is a hydrogen chloride solution and the aqueous solvent having a pH above 7 is a brine solution.

[0066] In a further presently preferred embodiment according to the invention, the concentration of salt in the aqueous solvent is in the range of 1 g L1to 350 g L1, preferably 20 g L1to 250 g L1, more preferably 50 g L_|to 150 g L1.

[0067] It was found that the concentration of salt in the aqueous solvent is preferably in the range of 1.01 g L_|to 1.74 g L1, preferably 1.03 g L_|to 1.49 g L1, more preferably 1.15 g L1to 1.49 g L1.

[0068] In a further presently preferred embodiment according to the invention, the salt may be one or more selected from the group of sodium chloride, potassium chloride, sodium bromide, potassium bromide.

[0069] In a further presently preferred embodiment according to the invention, the method further comprises the step of decreasing and / or increased the salt concentration in the aqueous solvent.

[0070] The invention also relates to a use of the multi-part dissolvable flow-plug according to the invention in oil drilling and / or gas drilling.

[0071] The use of the multi-part dissolvable flow-plug according to the invention provides the same or similar effects and advantages as those described for the multi-part dissolvable flow-plug according to the invention, well system in subterranean formation according to the invention, and the method for removing a multi-part dissolvable flow-plug according to the invention.

[0072] A further advantage of the use of the multi-part dissolvable flow-plug according to the invention is that no fluids (such as an aqueous solventO are mixed along the lateral and that said fluids do not become contaminated by mixing. As a result, the fluids can be reused.

[0073] Yet a further advantage of the use of the multi-part dissolvable flow-plug according to the invention is that an early breakthrough is achieved, wherein 80% of the multi-part dissolvable flowplugs provided to a liner were dissolved within substantially the same period.

[0074] Further advantages, features and details of the invention are elucidated on the basis of preferred embodiments thereof, wherein reference is made to the accompanying drawings, in which:

[0075] - Figure 1 shows a schematic overview of the method according to the invention;

[0076] - Figure 2 shows a schematic overview of the multi-part dissolvable flow-plug according to the invention;

[0077] - Figure 3 shows a liner comprising at least one multi-part dissolvable flow-plug according to the invention; and

[0078] - Figure 4 shows dissolving of a second part having a diameter of 28 mm of a flow-plug according to the invention.Method 10 (Figure 1) for removing a multi-part dissolvable flow-plug according to the invention follows a sequence of different steps.

[0079] In an illustrated embodiment method 10 may start with step 12 of providing an aqueous solvent to the inside and / or outside of the well system, followed by step 14 of circulating the solvent inside and / or outside the well system to dissolve at least a portion of the at least two parts facing the inside and / or outside of the well system.

[0080] In a preferred embodiment, step 12 is followed by step 16 of amending and / or changing the aqueous solvent, wherein step 16 is followed by step 14 of circulating the solvent inside and / or outside the well system to dissolve at least a portion of the at least two parts facing the inside and / or outside of the well system. In addition, step 18 of decreasing and / or increased the salt concentration in the aqueous solvent may be part of step 16 of amending and / or changing the aqueous solvent.

[0081] In an illustrated embodiment, closed nozzle 50 (Figure 2) is shown. Nozzle 50 comprises nozzle unit 52 (also referred to as nozzle housing) and multi-part dissolvable flow-plug 54. Multipart dissolvable flow-plug 54 comprises a first part 56 made of an aqueous dissolvable material comprising an aqueous dissolvable metal, second part 58 made of a polyester which is soluble in an aqueous solvent, and third part 60 made of an aqueous dissolvable material comprising an aqueous dissolvable metal. Furthermore, nozzle 50 further comprises assembling means 62 which are configured to hold nozzle 50 in the desired position in a liner.

[0082] It is noted that surface A is exposed to a well and is therefore part of the outer surface of a liner. Furthermore, surface B is exposed to the inner side of the liner and is therefore part of the inner surface of the liner.

[0083] In an illustrated embodiment, well system 100 (Figure 3) is shown. Well system 100 comprises liner 102 and nozzle 104. Nozzle 104 comprises multi-part dissolvable flow-plug 106.

[0084] It is noted that the dimensions of nozzle 50 and nozzle 104 are defined by the use of said nozzle. In other words, the multi-part dissolvable flow-plug according to the invention may have several dimensions and / or shapes.

[0085] In an experiment, the dissolving rate of the second part of a multi-part dissolvable flow-plug according to the invention was analysed (Figure 4). Figure 4 shows the dissolution of several types of the flow-plug according to the invention. The x-axis refers to the length of the flow-plug in milli meter, and the y-axis refers to the time in hours it takes for full dissolution of the flow-plug. The plugs have a diameter of 28 mm.

[0086] The top line (indicated with a star) refers to the second part of a multi-part dissolvable flowplug comprising according to the invention, wherein the second part is made of 100 wt.% polylactic acid. The second from the top line (indicated with triangles) refers to the second part of a multi-part dissolvable flow-plug according to the invention, wherein the second part is made of 50 wt.% poly(glycolic acid) and 50 wt.% polylactic acid. The second from the bottom line (indicated withcircles) refers to the second part of a multi-part dissolvable flow-plug according to the invention, wherein the second part is made of 75wt.% poly(glycolic acid) and 25 wt.% polylactic acid. The bottom line (indicated with crosses) refers to the second part of a multi-part dissolvable flow-plug according to the invention, wherein the second part is made of 100 wt.% poly(glycolic acid).

[0087] The aqueous solution used to dissolve the third part was a 2 M HC1 solution, to dissolve the second first part was a 2 M HC1 solution which was changes to a brine solution, and to dissolve the first part was a brine solution.

[0088] It was found that shorter plugs have a lower dissolution time and that plugs having two parts also have a lower dissolution time.

[0089] In a further experiment aqueous dissolvable material comprising an aqueous dissolvable metal suitable for the first and / or third part were made. Said aqueous dissolvable material comprises metals in and amount as disclosed in Table 1. It is noted that the total amount of the metals in the aqueous dissolvable material comprising a metal adds up to 100 wt.%.

[0090] Table 1: weight percentages of metals present in the aqueous dissolvable material comprising metals

[0091]

[0092] Specific examples of the aqueous dissolvable material comprising an aqueous dissolvable metal used in the first part and / or third part of the multi-part dissolvable flow-plug according to the invention are provided in Table 2.Table 2: specific examples of the aqueous dissolvable material comprising an aqueous dissolvable metal used in the first part and / or third part of the multi-part dissolvable flow-plug according to the invention

[0093]

[0094] It was found that the examples according to Table 2 provide an efficient and effective first part and / or third part of the multi-part dissolvable flow-plug according to the invention.

[0095] In a further experiment, plugs comprising three parts was tested in a liner (see Table 3). It was found that the plugs dissolved in an efficient and constant manner.

[0096] It is noted that the first part is made of 90 wt.% magnesium and 10 wt.% aluminium having a length 2.5 mm and a diameter of 2.8 mm, the second part is made of 100 wt.% poly(glycolic acid) having a length of 7 mm and a diameter of 2.8 mm, and the third part is made of 60 wt.% magnesium and 20 wt.% aluminium, 10 wt.% copper, and 10 wt.% yttrium, having a length of 1.5 mm and a diameter of 2.8 mm.

[0097] Table 3: dissolving experiment of a multi-part dissolvable flow-plug according to the invention

[0098] <

[0099]

[0100]

[0101] The present invention is by no means limited to the above described preferred embodiments and / or experiments thereof. The rights sought are defined by the following claims within the scope of which many modifications can be envisaged.

Claims

CLAIMS1. Multi-part dissolvable flow-plug comprising at least two parts, wherein the at least two parts comprising:- a first part made of an aqueous dissolvable material comprising an aqueous dissolvable metal; and- a second part made of a polyester which is soluble in an aqueous solvent, wherein the at least two parts are assembled adjacent to each other.

2. Multi-part dissolvable flow-plug according to claim 1, comprising at least three parts, wherein the third part of the at least three parts is made of an aqueous dissolvable material comprising an aqueous dissolvable metal, and wherein the second part is at least on one side delineated by the first part and on another side delineated by the third part.

3. Multi-part dissolvable flow-plug according to claim 2, wherein the first part made of an aqueous dissolvable material which dissolves in an aqueous solvent having a pH above 7, and wherein the third part made of an aqueous dissolvable material comprising an aqueous dissolvable metal which dissolves in an aqueous solvent having a pH below 7.

4. Multi-part dissolvable flow-plug according to any one of the preceding claims, wherein the polyester has a melting temperature of at least 130 °C, preferably of at least 150 °C, more preferably of at least 170 °C, most preferably of at least 200 °C.

5. Multi-part dissolvable flow-plug according to any one of the preceding claims, wherein the polyester is poly(glycolic acid) and / or polylactic acid.

6. Multi-part dissolvable flow-plug according to any one of the preceding claims, wherein the aqueous dissolvable metal of the dissolvable material comprises one or more metal selected from the group of magnesium, aluminium, zinc, iron, copper, manganese, nickel, calcium, gadolinium, yttrium.

7. Multi-part dissolvable flow-plug according to any one of the preceding claims, wherein the aqueous dissolvable material comprising an aqueous dissolvable metal is an alloy.

8. Multi-part dissolvable flow-plug according to any one of the preceding claims, wherein the aqueous dissolvable material comprising an aqueous dissolvable metal further comprises adepassivating agent, wherein the depassivating agent is one or more selected from the group of gallium, indium, tin.

9. Multi-part dissolvable flow-plug according to any one of the preceding claims, when dependent on claim 2, wherein the aqueous dissolvable material of the first part and the aqueous dissolvable material of the third part are different compositions.

10. Multi-part dissolvable flow-plug according to any one of the preceding claims, when dependent on claim 2, wherein the second part is made of poly(glycolic acid) and / or polylactic acid, wherein the first part and the third part are made of different materials, and wherein the first part comprises a depassivating agent.

11. Well system in subterranean formation, comprising a multi-part dissolvable flow-plug according to any one of the preceding claims and a nozzle, wherein the nozzle comprises a flow path which provides fluid communication from one side of the nozzle to another side of the nozzle, and wherein the multi-part dissolvable flow-plug is assembled within the nozzle such that the flow path is blocked prior to use.

12. Well system according to claim 11, comprising multiple combinations of the multi-part dissolvable flow-plug and the nozzle.

13. Well system according to claim 11 or 12, further comprising a liner comprising an outer wall, wherein the outer wall is configured to hold one or more nozzles.

14. Method for removing a multi-part dissolvable flow-plug according to any one of the claims 1 to 10 from a well system according to any one of the claims 11 to 13, comprising the steps of:providing an aqueous solvent to the inside and / or outside of the well system; and circulating the solvent inside and / or outside the well system to dissolve at least a portion of the at least two parts facing the inside and / or outside of the well system.

15. Method according to the foregoing claim, further comprising the step of amending and / or changing the aqueous solvent.

16. Method according to claim 14 or 15, wherein the aqueous solvent comprises one or more salts.

17. Method according to claim 16, wherein the concentration of salt in the aqueous solvent is in the range of 1 g L1to 350 g L1, preferably 20 g L1to 250 g L1, more preferably 50 g L1to 150 g L-1.

18. Method according to claim 16 or 17, wherein the salt is one or more selected from the group of sodium chloride, potassium chloride, sodium bromide, potassium bromide.

19. Method according to any one of the claims 16to 18, further comprising the step of decreasing and / or increased the salt concentration in the aqueous solvent.

20. Use of the multi-part dissolvable flow-plug according to any one of the claims 1 to 10 in oil drilling and / or gas drilling.

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