Apparatus for indicating a characteristic

Abstract

An apparatus (1100) for indicating a characteristic comprising a first indicator component (1102), and a mounting unit (1104) configured to hold the first indicator component (1102) in a first position, and move the first indicator component (1102) to a second position in response to the detection of a first characteristic, wherein the apparatus (1100) is configured to exhibit a visual change when the first indicator component (1102) moves from the first position to the second position, thereby indicating the first characteristic.

Description

[0001] APPARATUS FOR INDICATING A CHARACTERISTIC

[0002] The present disclosure relates to an apparatus for indicating a characteristic.

[0003] BACKGROUND

[0004] Detectors that provide an indication when they have detected a specific characteristic are ubiquitous in many fields of technology.

[0005] For example, it can be useful to detect characteristics of a subsea environment. For example, for environmental purposes or for the monitoring of undersea equipment such as subsea wells. Useful characteristics to detect include, but are not limited to, the presence of a specific chemical or chemicals, pH, and temperature.

[0006] Detecting a characteristic of a subsea environment may be preformed in situ, and within the subsea environment. Alternatively, detecting of the characteristic of the subsea environment may be performed outside of the subsea environment, for example on land and in a lab-based setting. For example, an operator may collect a sample of the seawater from a region that is being monitored, and analyse the sample in a laboratory to assess whether a specific chemical is present.

[0007] Figure 1(a) is a schematic of a subsea hydrocarbon well apparatus 5 as is known in the prior art (WO 2019 / 215438). The apparatus 5, e.g. a drilling system or a production system, facilitates access to or extraction of a resource, such as oil or natural gas, from a sub-surface reservoir 35 through a well 40. The apparatus 5 is generally depicted as an offshore drilling apparatus 5 including a drilling rig 10 on the sea surface 6, coupled with a riser 15 to a blowout preventer (BOP) 20 and a wellhead assembly 25 installed at the well 40. The wellhead assembly is located on the seabed 30 and is connected to a sub-surface 35 casing scheme 45 previously installed for the purpose of producing hydrocarbons.At the end of the productive life of a subsea oil or gas well, there is typically a requirement to make the well safe and to remove production-related infrastructure from the seabed. Several techniques exist and are under development for the sequence of activities generally referred to as decommissioning a well, including Plugging and Abandonment (P&A). These activities might include creating multiple barriers between the sub-surface reservoir (which might be a considerable distance below the seabed) and the wellhead location on the seabed through which previous drilling and production activities have been performed.

[0008] Figure 1(b) is a schematic of a decommissioned well 101 as is known in the prior art (WO 2019 / 215438). In the schematic there is shown a mechanical bridge plug 80, a cement plug 85, a volume of kill fluid 90, a mechanical bridge plug 95, a cement plug 100, a volume of kill fluid 105, a mechanical bridge plug 110, and a cement plug 115.

[0009] Although multiple barriers are created during decommissioning between a reservoir and the external environment, there are multiple potential leak paths that can result from processes including corrosion of the metalwork such as the casing and / or deformation caused by geological movement. Examples of potential leak paths include micro-annuli at the interface between casing and cement caused by channels and the presence of materials such as wax, scale, oil and dirt; connected pores, cracks and channels caused by permeability in cement; and through perforations of casing caused by corrosion and mechanical deformation.

[0010] Such leak paths may occur at any depth within the well arrangement and give rise to the propagation or migration of hydrocarbons 130 through the sub-surface geology 35. The sub-surface post-decommissioning leak path example 120 shown in Figure 1(b) may give rise to leaked material 135 emerging from the seabed 30 into the subsea environment. Whereas leaks may occur along the axis of the predecommissioned well bore 125, they may also remain close to the casing scheme or take any other path of least resistance to the seabed 30 such as paths 130.Upon completion of well decommissioning activities, it may therefore be desirable to monitor the environment around a well site for an extended period to provide reassurance that a well’s integrity is secure and that hydrocarbons from the reservoir are not leaking into the subsea environment. Several conventional systems are currently available to address this requirement, using approaches including active acoustics, bio sensors, capacitance, fibre optics, fluorescence, optical sniffers, optical cameras and passive acoustics.

[0011] An example of a leak from a reservoir is shown in Figure 1(b) where leak paths 130 are related to breaches of well barriers, but path 131 is not, as it occurs below the first barrier 80 and thus originates within the reservoir (being the material previously installed by the bull heading procedure).

[0012] WO 2019 / 215438 describes a passive detection system for use in monitoring the integrity of abandoned, suspended and / or decommissioned subsea wells or carbon dioxide sequestration reservoirs. Such a system can achieve differentiation of the source of a leak thus minimising the probability of false alarms. This is achieved by using a tracer fluid 145 that is mixed with well kill fluid 90, 105 so that the presence and detection of said tracer fluid 145 in the external environment means it can only have come from within a well which has suffered a loss of integrity.

[0013] An example of this tracer fluid 145 is referred to as Sentinel Well Integrity Fluid Tracer (SWIFT) 145, available from Sentinel Subsea Limited of Aberdeen, UK. This fluid 145 may be supplied in concentrated or diluted form, pre-mixed with well kill fluid 90, 105 or added to kill fluid 90, 105 as the fluid 90, 105, 145 is pumped into a well during decommissioning activity.

[0014] It is desirable that SWIFT 145 has the following properties: it is not a naturally occurring material, so that it cannot be mistaken for any other substance, compound, fluid or particle that would be found in the subsea environment; it is inert with any material that might be in the well, e.g. cement, steel, alloys and casing; it is environmentally benign and does not pose a risk to human handlers.There are multiple mechanisms by which SWIFT 145 may migrate from a kill fluid 90, 105 zone into a subsea environment. For example, rising naturally through any available leak path 130 in the same way as reservoir hydrocarbons; driven by reservoir pressure, i.e. by the force of the hydrocarbons leaking from the reservoir past the installed barriers; or chemically or mechanically liberated from the kill fluid 90, 105 as it comes into contact with leaking hydrocarbons, at which point SWIFT 145 is optionally bound chemically or mechanically to the hydrocarbons leaking from the reservoir past the barriers and carried to the subsea environment in combination with the hydrocarbons. Preferably SWIFT 145, or the material of interest that is being monitored, is less dense than water / sea water (or less dense than the sea water in the vicinity of the seabed where the monitoring apparatus is positioned), and therefore has a natural tendency to rise under its own inherent buoyancy.

[0015] The system disclosed in WO 2019 / 215438 provides passive monitoring of SWIFT 145 (or other predetermined chemicals that will provide the required properties to alert an operator to a loss of well integrity in the subsea environment). Whereas active monitoring systems are available to detect the presence of hydrocarbons or tracer fluids using a myriad of techniques, these generally require the use of active systems (therefore electrical power), sensors, processors and communication channels.

[0016] The passive detection of SWIFT 145 (or other appropriate predetermined chemical) is achieved by the use of one or more materials that react to the presence of SWIFT 145 (or other predetermined material) and thus provide a detection mechanism.

[0017] The passive detection of SWIFT 145 is achieved by the use of one or more materials that react to the presence of SWIFT 145. Several example embodiments are presented in WO 2019 / 215438.

[0018] Figure 1(c) is a schematic of a beacon release mechanism 200 that is triggered upon interaction with SWIFT 145 (or other pre-determined chemical) thereby providinga mechanism for alerting an operator to a leak from a decommissioned well, such as the well 101 shown in Figure 1(b) (WO 2019 / 215438).

[0019] In this example, the beacon release mechanism 200 attachment bracket is a simple ring 280 and the assembly is prevented from moving under buoyancy force 275 by trigger rod 285. In this embodiment, the trigger rod 285 directly restrains the beacon assembly 265 and the failure of the trigger rod 285, upon completion of a reaction and degradation process when the trigger rod 285 is in contact with SWIFT 145 (or another predetermined chemical), allows the beacon assembly 265 to ascend. When the beacon release mechanism 265 reaches the sea surface it may then notify an operator that there is a leak from the well 101.

[0020] In summary, the systems presented in WO 2019 / 215438 and illustrated in Figures 1(b) and 1(c) operate by gathering fluids of interest (liquid or gas) and directing these fluids to a chamber where they interact with and degrade trigger materials that restrain a buoyant beacon.

[0021] Although the above relates to decommissioned wells, it is also useful to monitor suspected leaks from wells during their active lifecycle.

[0022] Production wells may temporarily halt operation due to the presence or suspected presence of a leak.

[0023] These leaks may be of non-hydrocarbon fluids such as control fluids or flow assurance chemicals but nonetheless are of sufficient concern that the operator is obliged to investigate. Shutdown of a well for multiple days can lead to a loss of significant amounts of money.

[0024] Such a leak may be observed by a submersible vehicle such as a remotely operated underwater vehicle (ROV) and may appear as a “haze” on the screen of an ROV. The inability to characterise the nature of the leak from a visual inspection of the haze can mean that multiple investigations are required to properly assess thecomposition of the haze. These investigations would typically be carried out using crude apparatuses, leading to unsatisfactory results.

[0025] There is also a safety concern in relation to these investigations. If a gas leak is observed, with samples of the gas being captured by a traditional ROV-held funnel-into-bottle method, then the bottle is typically returned to surface. The bottle thereafter poses a hazard since that vessel then contains pressure. It is generally preferred by operators to avoid putting pressurised vessels onto helicopters for transfer to land but sometimes this is necessary to enable a chemical analysis to be performed. For example, the vessel may then be transferred to a laboratory for isotope analysis, e.g. to confirm the presence of thermogenic gas.

[0026] This process represents a delay in characterising the gas, it introduces a risk to personnel and equipment, and it can be costly.

[0027] It will be appreciated that the above examples primarily relate to the detection of chemicals from subsea wells. However, as discussed previously chemical detection may also be desirable for other applications. Similarly, it may be desirable to identify other characteristics of a subsea environment such as pH and temperature.

[0028] SUMMARY

[0029] It is desirable to provide an improved system for detecting one or more characteristics, for example, of a subsea environment.

[0030] According to a first aspect of the disclosure there is provided an apparatus for indicating a characteristic comprising a first indicator component, and a mounting unit configured to hold the first indicator component in a first position, and move the first indicator component to a second position in response to the detection of a first characteristic, wherein the apparatus is configured to exhibit a visual change when the first indicator component moves from the first position to the second position, thereby indicating the first characteristic.Optionally, the apparatus is for indicating a characteristic of a subsea environment,

[0031] Optionally, the visual change from the movement of the first indicator component from the first position to the second position indicates the first characteristic of the subsea environment.

[0032] Optionally, the apparatus is configured to function on land and / or in a subsea environment.

[0033] Optionally, the first indicator component comprises one or more first visual indication sections, each of the one or more first visual indication sections being configured to be in a first visible position when the first indicator component is in the first position, and in a first concealed position when the first indicator component is in the second position.

[0034] Optionally, the mounting unit comprises one or more first viewing ports, each of the one or more first viewing ports being configured to permit visible inspection of one of the first visual indication sections when it is in the first visible position.

[0035] Optionally, the mounting unit comprises one or more first orifices, each of the one or more first orifices being configured to permit passage of another one of the first visual indication sections from the first visible position outside the mounting unit to the first concealed position within the mounting unit.

[0036] Optionally, the mounting unit comprises one or more first orifices, each of the one or more first orifices being configured to permit passage of one of the first visual indication sections from the first visible position outside the mounting unit to the first concealed position within the mounting unit.

[0037] Optionally, the first indicator component comprises one or more second visual indication sections, each of the one or more second visual indication sections being configured to be in a second concealed position when the first indicator componentis in the first position, and in a second visible position when the first indicator component is in the second position.

[0038] It will be appreciated that the labelling of a “second” component or feature is simply used to distinguish from a “first” component or feature. Reference to a “first” component does not necessarily require that a “second” component is present. Similarly, a “second” component does not necessarily require that at least two components are present, and a “second” component without any additional components may be relabeled as the “first” component or, simply, “the component”.

[0039] For example, the first indicator component may comprise one or more first visual indication sections and / or one or more second visual indication sections.

[0040] It will be appreciated that this principle also applies for other labelling, such as for “third” and “fourth” components, in accordance with the understanding of the skilled person.

[0041] Optionally, the mounting unit comprises one or more second viewing ports, each of the one or more second viewing ports being configured to permit visible inspection of one of the second visual indication sections when it is in the second visible position.

[0042] Optionally, the mounting unit comprises one or more second orifices, each of the one or more second orifices being configured to permit passage of another one of the second visual indication sections from the second concealed position within the mounting unit to the second visible position outside the mounting unit.

[0043] Optionally, the mounting unit comprises one or more second orifices, each of the one or more second orifices being configured to permit passage of one of the second visual indication sections from the second concealed position within the mounting unit to the second visible position outside the mounting unit.Optionally, the first indicator component comprises one or more third visual indication sections, each of the one or more third visual indication sections being configured to be in a third visible position when the first indicator component is in the first position, and in a fourth visible position when the first indicator component is in the second position.

[0044] Optionally, the mounting unit comprises one or more third viewing ports, each of the one or more third viewing ports being configured to permit visible inspection of one of the first visual indication sections when it is in the third visible position, and one or more fourth viewing ports, each of the one or more fourth viewing ports being configured to permit visible inspection of the one of the first visual indications sections when it is in the fourth visible position.

[0045] Optionally, the mounting unit comprises one or more third orifices, each of the one or more third orifices being configured to permit passage of another one of the first visual indication sections from the third visible position to the fourth visible position

[0046] Optionally, for each of the one or more third visual indication sections, one of the third visible position and the fourth visible position is within the mounting unit and the other of the third visible position and fourth visible position is outside the mounting unit.

[0047] Optionally, the mounting unit comprises one or more third orifices, each of the one or more third orifices being configured to permit passage of one of the first visual indication sections from the third visible position to the fourth visible position.

[0048] Optionally, for each of the one or more third visual indication sections, one of the third visible position and the fourth visible position is within the mounting unit and the other of the third visible position and fourth visible position is outside the mounting unit.Optionally, the first indicator component is positioned at least partially within the mounting unit when in use.

[0049] Optionally, the first indicator component is substantially rectangular.

[0050] Optionally, the mounting unit comprises a biasing module configured to apply a biasing force to the first indicator component, and a retaining module configured to hold the first indicator component in the first position, release the first indicator component upon detection of the first characteristic, such that the biasing force applied by the biasing module moves the first indicator component to the second position.

[0051] Optionally, the biasing module comprises one or more biasing springs.

[0052] Optionally, each of the one or more biasing springs is positioned on a first edge of the first indicator component and a first interior edge of the mounting unit.

[0053] Optionally, the retaining module comprises one or more retaining portions, and each of the one or more retaining portions comprises a detection component for detecting the first characteristic.

[0054] Optionally, each of the one or more retaining portions comprises a retaining spring configured to hold the first indicator component in the first position, and for each of the one or more retaining portions, the detection component is configured to react to the first characteristic and, as a result of the reaction, to permit extension of the retaining spring.

[0055] Optionally, the first indicator component comprises an indention for each of the one or more retaining portions, each of the one or more retaining portions comprises a ball bearing, and for each of the one or more retaining portions, the retaining spring is configured to hold the first indicator component in the first position by pushing a ball bearing into one of the indentations.Optionally, for each of the one or more retaining portions the detection component is positioned between the retaining spring and the ball bearing, and the detection component is configured to react to the first characteristic, and permit extension of the retaining spring as a result of reacting to the first characteristic.

[0056] Optionally, each of the one or more retaining portions comprises a load spreader.

[0057] Optionally, the load spreader comprises one or more washers.

[0058] Optionally, the mounting unit comprises one or more fluid channels, each of the one or more fluid channels being configured to provide a fluid path to the detection component of one of the one or more retaining portions.

[0059] Optionally, the retaining module comprises a first retaining portion and a second retaining portion, the first retaining portion is arranged to contact a second edge of the first indicator component and the second retaining portion is arranged to contact a third edge of the first indicator component, and the second and third edge are opposing sides of the first indicator component.

[0060] Optionally, the retaining module comprises a first retaining portion and a second retaining portion, the first retaining portion is arranged to contact a second edge of the first indicator component and the second retaining portion is arranged to contact a third edge of the first indicator component, the second and third edge are opposing sides of the first indicator component, the mounting unit comprises a first fluid channel and a second fluid channel, each of the first and second fluid channels being configured to provide a fluid path to the detection component of the first retaining portion, and a third fluid channel and a fourth fluid channel, each of the third and fourth fluid channels being configured to provide a fluid path to the detection component of the second retaining portion.

[0061] Optionally, for each of the one or more retaining portions, the detection component is configured to chemically react upon detection of the first characteristic.Optionally, the first characteristic is the presence of a first pre-determined chemical.

[0062] Optionally, the first pre-determined chemical comprises a tracer fluid, and / or a thermogenic gas, and / or a biogenic gas, and / or methane, and / or a hydrocarbon, and / or methanol, and / or monoethylene glycol, and / or a control fluid, and / or carbon dioxide. Optionally, the tracer fluid is Sentinel Well Integrity Fluid Tracer (SWIFT). Optionally, the hydrocarbon is a liquid hydrocarbon.

[0063] Optionally, the apparatus is configured to monitor the integrity of a subsea well or a fluid sequestration site by indicating that the first pre-determined chemical has been detected.

[0064] Optionally, the apparatus comprises a second indicator component, wherein the mounting unit is configured to hold the second indicator component in a third position, and move the second indicator component to a fourth position in response to the detection of a second characteristic, wherein the apparatus is configured to exhibit a second visual change when the second indicator component moves from the third position to the fourth position, thereby indicating the second characteristic.

[0065] Optionally, the visual change from the movement of the second indicator component from the third position to the fourth position indicates the second characteristic of the subsea environment.

[0066] Optionally, the apparatus comprises a handle wherein the mounting unit is coupled to the handle. Optionally, the mounting unit comprises a first attachment portion for attaching the apparatus to a subsea tree. Optionally, the apparatus comprises a stand for standing the apparatus on the sea floor, wherein the mounting unit is coupled to the stand.

[0067] Optionally, the apparatus comprises a third indicator component, and a further mounting unit configured to hold the third indicator component in a fifth position,and move the third indicator component to a sixth position in response to the detection of a third characteristic, wherein the apparatus is configured to exhibit a third visual change when the third indicator component moves from the fifth position to the sixth position, thereby indicating the third characteristic.

[0068] Optionally, the visual change from the movement of the third indicator component from the fifth position to the sixth position indicates the third characteristic of the subsea environment.

[0069] Optionally, the further mounting unit is coupled to the mounting unit.

[0070] Optionally, moving the first indicator component to the second position in response to the detection of the first characteristic is a linear and / or rotational motion. Optionally, moving the second indicator component to the fourth position in response to the detection of the second characteristic is a linear and / or rotational motion. Optionally, moving the third indicator component to the sixth position in response to the detection of the third characteristic is a linear and / or rotational motion.

[0071] Optionally, the apparatus is configured to trigger a secondary action when the first indicator component moves from the first position to the second position. Optionally, the apparatus is configured to trigger a secondary action when the second indicator component moves from the third position to the fourth position. Optionally, the apparatus is configured to trigger a secondary action when the third indicator component moves from the fifth position to the sixth position.

[0072] Optionally, the secondary action is one or more of activating an audible indicator, transmitting a wireless signal, initiating an activation sequence of ordnance, controlling an electrical or magnetic switch, starting a mechanical device or a hydraulic device or a stored energy device, releasing a buoy or a beacon, opening or closing a valve, activating a solenoid, incrementing a counter, starting or stopping a timer and / or a clock.According to a second aspect of the disclosure there is provided a method of indicating a characteristic using the apparatus of the first aspect.

[0073] It will be appreciated that the method of the second aspect may include features set out in the first aspect and can incorporate other features as described herein.

[0074] BRIEF DESCRIPTION OF THE DRAWINGS

[0075] The disclosure is described in further detail below by way of example and with reference to the accompanying drawings in which:

[0076] Figure 1(a) is a schematic of a subsea hydrocarbon well apparatus as is known in the prior art, Figure 1(b) is a schematic of a decommissioned well as is known in the prior art, Figure 1(c) is a schematic of a beacon release mechanism;

[0077] Figure 2(a) is a schematic of an apparatus for indicating a characteristic of a subsea environment in accordance with a first embodiment of the present disclosure, Figure 2(b) is a schematic of a specific embodiment of the apparatus of Figure 2(a) in accordance with a second embodiment of the present disclosure, Figure 2(c) is a schematic of a specific embodiment of the apparatus of Figure 2(a) in accordance with a third embodiment of the present disclosure, Figure 2(d) is a schematic of a specific embodiment of the apparatus of Figure 2(a) in accordance with a fourth embodiment of the present disclosure, Figure 2(e) is a schematic of a specific embodiment of the apparatus of Figure 2(a) in accordance with an fifth embodiment of the present disclosure, Figure 2(f) is a schematic of a specific embodiment of the apparatus of Figure 2(a) in accordance with a sixth embodiment of the present disclosure, Figure 2(g) is a schematic of a specific embodiment of the apparatus of Figure 2(a) in accordance with a seventh embodiment of the present disclosure;

[0078] Figure 3(a) is a schematic of a specific embodiment of the apparatus as shown in Figure 2(c), and in accordance with a eighth embodiment of the present disclosure, Figure 3(b) is a schematic of the apparatus showing a specificembodiment of the apparatus of Figure 3(a), and in accordance with a ninth embodiment of the present disclosure;

[0079] Figure 4(a) is a schematic of a specific embodiment of the apparatus as shown in Figure 2(d), and in accordance with a tenth embodiment of the present disclosure, Figure 4(b) is a further schematic of the apparatus of Figure 4(a), Figure 4(c) is a perspective view of the schematic of the apparatus as shown in Figure 4(a), Figure 4(d) is a perspective view of the schematic of the apparatus as shown in Figure 4(b), Figure 4(e) is a schematic of a specific embodiment of the apparatus in accordance with a eleventh embodiment of the present disclosure, Figure 4(f) is a schematic of a further specific embodiment of the apparatus in accordance with a twelfth embodiment of the present disclosure, Figure 4(g) is a schematic of an exploded perspective view of a portion of the handle, Figure 4(h) is a schematic of a perspective view of the portion of the handle shown in Figure 4(g), Figure 4(i) is an exploded view of a specific embodiment of the mounting unit comprising three subcomponents, Figure 4(j) is a schematic of the mounting unit of Figure 4(i), Figure 4(k) is an exploded view schematic of a specific embodiment of the apparatus, Figure 4(1) is a schematic of a perspective view of the apparatus of Figure 4(k);

[0080] Figure 5(a) is a schematic of a specific embodiment of the apparatus in accordance with a thirteenth embodiment of the present disclosure, Figure 5(b) is a schematic of a zoomed in portion of Figure 5(a), Figure 5(c) is an alternative schematic of the apparatus of Figure 5(a), Figure 5(d) is a perspective view of the apparatus of Figure 5(a), Figure 5(e) is an exploded perspective view of the schematic of the apparatus of Figure 5(d), Figure 5(f) is a schematic of the apparatus of Figure 5(a) with the indicator component in the second position, Figure 5(g) is a perspective view of the apparatus of Figure 5(f) with the upper surface of the mounting unit being displayed;Figure 5(h) is a schematic of a specific embodiment of the apparatus in accordance with a fourteenth embodiment of the present disclosure;

[0081] Figure 6(a) is a schematic of a specific embodiment of the apparatus in accordance with a fifteenth embodiment of the present disclosure, Figure 6(b) is a schematic of the apparatus of Figure 6(b) with the indicator component being in the second position, Figure 6(c) is a schematic of the apparatus of Figure 6(a) with theupper surface of the mounting unit being visible, Figure 6(d) is a perspective view of the apparatus of Figure 6(c), Figure 6(e) is a further perspective view of the apparatus of Figure 6(c);

[0082] Figure 7(a) is a schematic of a specific embodiment of the apparatus in accordance with a sixteenth embodiment of the present disclosure, Figure 7(b) is a perspective view of the apparatus of Figure 7(a), Figure 7(c) is a schematic of a specific embodiment of the apparatus in accordance with a seventeenth embodiment of the present disclosure, Figure 7(d) is a schematic of the apparatus of Figure 7 (c) with the indicator component being in the second position, Figure 7 (e) is an exploded view schematic of the apparatus of Figure 7(c);

[0083] Figure 8(a) is a schematic of a specific embodiment of the apparatus in accordance with a eighteenth embodiment of the present disclosure, Figure 8(b) is a schematic of a specific embodiment of the apparatus in accordance with a nineteenth embodiment of the present disclosure, Figure 8(c) is a schematic of a specific embodiment of the apparatus in accordance with a twentieth embodiment of the present disclosure, Figure 8(d) is a schematic of a specific embodiment of the apparatus in accordance with a twenty first embodiment of the present disclosure;

[0084] Figure 9(a) is a schematic of a specific embodiment of the apparatus in accordance with a twenty second embodiment of the present disclosure, Figure 9(b) is a schematic of the apparatus of Figure 9(a) with the indicator components in different positions, Figure 9(c) is a schematic of the apparatus of Figure 9(b) with the indicator components in different positions;

[0085] Figure 10(a) is a schematic of a specific embodiment of the apparatus in accordance with a twenty third embodiment of the present disclosure, Figure 10(b) is a further schematic of the apparatus of Figure 10(a);

[0086] Figure 11(a) is a schematic of a specific embodiment of the apparatus in accordance with a twenty fourth embodiment of the present disclosure, Figure 11(b) is a schematic of the apparatus of Figure 11(a) where the indicator component is in the first position, Figure 11(c) is a schematic of the apparatus of Figure 11(a) where the indicator component has transitioned to the second position, Figure 11(d) is a cross section schematic of the apparatus of Figure 11(a), Figure 11(e) is across section schematic of the apparatus of Figure 11(b), Figure 11(f) is a cross section schematic of the apparatus of Figure 11(c); and

[0087] Figure 12(a) is a schematic of a specific embodiment of the apparatus in accordance with a twenty fifth embodiment of the present disclosure, Figure 12(b) is a schematic of the apparatus of Figure 12(a) where the indicator component has transitioned to the second position, Figure 12(c) is a cross section schematic of the apparatus of Figure 12(a), 12(d) is a cross section schematic of the apparatus of Figure 12(b).

[0088] DETAILED DESCRIPTION

[0089] Figure 2(a) is a schematic of an apparatus 1100 for indicating a characteristic in accordance with a first embodiment of the present disclosure. The apparatus 1100 may be for indicating the characteristic of a subsea environment. In operation, the apparatus 1100 is placed in the subsea environment. However, it will be appreciated that in further embodiments, the apparatus 1100 may not be positioned in the subsea environment, and may, for example, be used on land, offshore and in a labbased setting.

[0090] The present embodiment, and subsequent embodiments, are described primarily in relation to the indication of a characteristic of a subsea environment. However, it will be appreciated that the apparatus 1100, and other apparatuses described herein, may be applied more generally to detect a “characteristic”. For example, chemical detection, pH detection or temperature detection in any technical field, such as healthcare.

[0091] Furthermore, it will be appreciated that the apparatus 1100, and other apparatuses described herein, may be used in any suitable environment, in accordance with the understanding of the skilled person. For example, the apparatus 1100 may be placed in the subsea environment that is to be monitored. Alternatively, the apparatus 1100 may be on-land, with a sample of the subsea environment being provided to the apparatus 1100 for testing.It will be appreciated that the characteristic may be referred to as a “predetermined” characteristic.

[0092] The apparatus 1100 comprises an indicator component 1102 and a mounting unit 1104. The mounting unit 1104 is configured to hold the indictor component 1102 in a first position, as shown in the leftmost image of Figure 2(a).

[0093] The mounting unit 1104 is further configured to move the indicator component 1102 to a second position in response to the detection of the pre-determined characteristic, as shown in the rightmost image of Figure 2(a). The second position may be referred to as the “alert position” as it is indicative of the pre-determined characteristic having been detected. The indicator component 1102 moving to the second position in response to the detection of the pre-determined characteristic may, for example, be a linear and / or rotational motion.

[0094] The apparatus 1100 is configured to exhibit a visual change when the indicator component 1102 moves from the first position to the second position, for example as shown by the difference in visual appearance between the leftmost and rightmost images of Figure 2(a). As the movement of the indicator component 1102 and therefore the visual change is triggered by the detection of the pre-determined characteristic, the visual change functions as an indicator of the pre-determined characteristic.

[0095] The indicator component 1102 may be positioned at least partially within the mounting unit 1104 when in use. The indicator component 1102 may be substantially rectangular.

[0096] It will be appreciated that in specific embodiments, the visual change of the apparatus 1100 may be irreversible, in that after the apparatus 1100 is no longer being exposed to the characteristic the visual change remains. However, in further embodiments, the visual change may be reversible, where the appearance of theapparatus 1100 returns to its initial appearance after it stops being exposed to the characteristic.

[0097] In further embodiments, the apparatus 1100 may undergo different visual changes based on the characteristic or characteristics that it is exposed to.

[0098] In a specific embodiment, the visual change may be observable by a human user simply looking directly at the apparatus 1100. The visual change maybe observable in an image acquired, for example, by a camera controlled by an ROV. In specific embodiments, the visual change may be observable in the reflection and / or transmission spectrum of the apparatus 1100.

[0099] In further embodiments, the visual change may only be observable using imaging equipment as may be held and operated using an ROV. For example, the visual change may occur outside of the visible wavelength range, such as at ultraviolet or infrared wavelengths. For example, where a visual change occurs at infrared wavelengths, an infrared camera may be used to observe the visual change.

[0100] In specific embodiments, the pre-determined characteristic that is detected may be the presence of a pre-determined chemical, such that during operation, the visual change of the apparatus 1100 occurs when the pre-determined chemical is detected in the subsea environment.

[0101] The pre-determined chemical may comprise one or more of a tracer fluid, a thermogenic gas, a biogenic gas, methane, a hydrocarbon, methanol, monoethylene glycol, a control fluid, carbon dioxide. The hydrocarbon may, for example, be a liquid hydrocarbon. In further embodiments, the pre-determined chemical may comprise any other fluid for which responsive materials have been developed.

[0102] As discussed previously, a tracer fluid can be used with a well kill fluid, where the presence of the tracer fluid can be indicative of a well losing integrity. Examples oftracer fluids are described in W02019215438A1. The tracer fluid may, for example, be Sentinel Well Integrity Fluid Tracer (SWIFT).

[0103] In a specific embodiment, the apparatus 1100 may be configured to monitor the integrity of a subsea well or a fluid sequestration site by indicating that the predetermined chemical (that may be indicative of a leak) has been detected.

[0104] As discussed previously ROV inspection can take a long time to conduct an inspection and there are safety concerns in extracting chemicals for analysis outside of the subsea environment. Embodiments of the present disclosure can accelerate inspection by instructing the ROV to look only at specific areas of interest, for example by looking at one or more apparatuses 1100 of the present disclosure, and confirming the occurrence, or non-occurrence, of a visual change.

[0105] Specific embodiments of the apparatus 1100 can eliminate the requirement to extract the chemicals for analysis outside of the subsea environment, thereby improving safety over known systems.

[0106] In further embodiments, the characteristic that is detected may relate to temperature. For example, the characteristic may be the temperature of the subsea environment being greater than a threshold temperature value, less than the threshold temperature value, or approximately equal to the threshold temperature value.

[0107] In further embodiments, the characteristic that is detected may relate to the pH value of the subsea environment. For example, the characteristic may be the pH value of the subsea environment being greater than a threshold pH value, less that a threshold pH value, or approximately equal to a threshold pH value.

[0108] In further embodiments, the apparatus 1100 may be configured to trigger a secondary action when the indicator component 1102 moves from the first position to the second position.

[0109] For example, the secondary action may be one or more of:• activating an audible indicator, e.g. a noise maker / buzzer / acoustic unit • triggering a wireless signal, including through water RF

[0110] • initiating activation / firing sequence of ordnance

[0111] • controlling an electrical or magnetic switch, e.g. for a beacon / transmitter / flasher

[0112] • starting a mechanical device / a hydraulic device / a stored energy device (including energetic materials)

[0113] • releasing a device, e.g. buoy, beacon

[0114] • opening / closing a valve (with or without secondary / tertiary stored energy assistance)

[0115] • activating a solenoid, e.g. thereby injecting a signal into a control system • incrementing a counter

[0116] • starting or stopping a timer (with or without subsea display) for relative time • starting or stopping a clock (with or without subsea display), e.g. to show when an event happened (absolute time)

[0117] Figure 2(b) is a schematic of a specific embodiment of the apparatus 1100 of Figure 2(a) in accordance with a second embodiment of the present disclosure.

[0118] In the present embodiment, the indicator component 1102 comprises a visual indication section 1106. The visual indication section 1106 may refer to a portion of the overall indicator component 1102 that includes a distinctive marking that can easily be seen by an observer. In the schematic of Figure 2(b) the visual indication section 1106 is illustrated as a circle with a hatched pattern.

[0119] The dashed line of the indicator component 1102 is to illustrate the extent of the indicator component 1102, which is partially concealed by a surface of the mounting unit 1104 in the leftmost image and is fully concealed in the rightmost image.

[0120] It will be appreciated that in further embodiments, the indicator component 1102 may comprise two or more visual indication sections 1106. The present example relates to a single visual indication section 1106 and it will be clear to the skilledperson that additional visual indication sections may function substantially as described for the single visual indication section 1106.

[0121] In the present example, when the indicator component 1102 is in the first position (the leftmost image), the visual indication section 1106 is in a visible position; when the indicator component 1102 is in the second position (the rightmost image) the visual indication section 1106 is in a concealed position.

[0122] The mounting unit 1104 comprises a viewing port 1108 that permits visible inspection of the visual indication section 1106 when it is in the visible position. It will be appreciated that for embodiments having further visual indication sections there may be additional viewing ports, in accordance with the understanding of the skilled person.

[0123] In operation, the visual indication section 1106 is visible when in the visible position as shown by the leftmost image where the visible indication section 1106 can be seen through the viewing port 1108. When the pre-determined characteristic is detected, the indicator component 1102 moves to the second position, such that the visual indication section 1106 is then concealed within the mounting unit 1104. In this configuration, the viewing port 1108 does not show any visual indication section 1106. Therefore, in the present example, the apparatus 1100 has undergone a visual change, which is indicative of the detection of the pre-determined characteristic.

[0124] Figure 2(c) is a schematic of a specific embodiment of the apparatus 1100 of Figure 2(a) in accordance with a third embodiment of the present disclosure.

[0125] In the present example, visual indication section 1106 is concealed when the indicator component 1102 is in the first position (leftmost image), and visible via a viewing port 1110 of the mounting unit 1104 when the indicator component 1102 is in the second position (rightmost image).In summary, in operation, the visual indication section 1106 is concealed when in the concealed position as shown by the leftmost image where the visible indication section 1106 cannot be seen. When the pre-determined characteristic is detected, the indicator component 1102 moves to the second position, such that the visual indication section 1106 is then visible within the mounting unit 1104. In this configuration, the viewing port 1110 shows the visual indication section 1106. Therefore, in the present example, the apparatus 1100 has undergone a visual change, which is indicative of the detection of the pre-determined characteristic.

[0126] Figure 2(d) is a schematic of a specific embodiment of the apparatus 1100 of Figure 2(a) in accordance with a fourth embodiment of the present disclosure.

[0127] In the present example, visual indication section 1106 is visible via the viewing port 1108 when the indicator component 1102 is in the first position (leftmost image), and visible via the viewing port 1110 of the mounting unit 1104 when the indicator component 1102 is in the second position (rightmost image).

[0128] In summary, in operation, the visual indication section 1106 is visible through different viewing ports 1108, 1110 before and after detection of the pre-determined characteristic, such that the apparatus 1100 undergoes a visual change that is indicative of the pre-determined characteristic.

[0129] Figure 2(e) is a schematic of a specific embodiment of the apparatus 1100 of Figure 2(a) in accordance with an fifth embodiment of the present disclosure.

[0130] In the present example, the visual indication section 1106 is a rectangular “flag” that protrudes from the mounting unit 1104 in one configuration and is held within the mounting unit 1104 in another configuration.

[0131] In the present example, when the indicator component 1102 is in the first position (the leftmost image), the visual indication section 1106 is in a visible position; whenthe indicator component 1102 is in the second position (the rightmost image) the visual indication section 1106 is in a concealed position.

[0132] In the present example, the mounting unit 1104 comprises an orifice 1112 that permits passage of the visual indication section 1106 from the visible position where the visual indication section 1106 protrudes from the mounting unit 1104, to the concealed position within the mounting unit 1104.

[0133] It will be appreciated that for embodiments having further visual indication sections there may be additional orifices, in accordance with the understanding of the skilled person.

[0134] In operation, the visual indication section 1106 is visible when in the visible position as shown by the leftmost image where the visible indication section 1106 protrudes from the mounting unit 1104. When the pre-determined characteristic is detected, the indicator component 1102 moves to the second position, such that the visual indication section 1106 is then concealed within the mounting unit 1104. Therefore, in the present example, the apparatus 1100 has undergone a visual change, which is indicative of the detection of the pre-determined characteristic.

[0135] Figure 2(f) is a schematic of a specific embodiment of the apparatus 1100 of Figure 2(a) in accordance with a sixth embodiment of the present disclosure.

[0136] In the present example, when the indicator component 1102 is in the first position (the leftmost image), the visual indication section 1106 is in a concealed position; when the indicator component 1102 is in the second position (the rightmost image) the visual indication section 1106 is in a visible position.

[0137] In the present example, the mounting unit 1104 comprises an orifice 1112 that permits passage of the visual indication section 1106 from the concealed position where the visual indication section 1106 is within the mounting unit 1104, to the visible position outside the mounting unit 1104.It will be appreciated that for embodiments having further visual indication sections there may be additional orifices, in accordance with the understanding of the skilled person.

[0138] In operation, the visual indication section 1106 is concealed when in the concealed position as shown by the leftmost image where the visible indication section 1106 is within the mounting unit 1104. When the pre-determined characteristic is detected, the indicator component 1102 moves to the second position, such that the visual indication section 1106 is then passed outside the mounting unit 1104 via the orifice 1112. Therefore, in the present example, the apparatus 1100 has undergone a visual change, which is indicative of the detection of the pre-determined characteristic.

[0139] Figure 2(g) is a schematic of a specific embodiment of the apparatus 1100 of Figure 2(a) in accordance with a seventh embodiment of the present disclosure.

[0140] In the present example, when the indicator component 1102 is in the first position (the leftmost image), the visual indication section 1106 is in a visible position; when the indicator component 1102 is in the second position (the rightmost image) the visual indication section 1106 is in a different visible position.

[0141] In the present example, the mounting unit 1104 comprises an orifice 1112 that permits passage of the visual indication section 1106 from the initial visible position, to a different visible position.

[0142] It will be appreciated that for embodiments having further visual indication sections there may be additional orifices, in accordance with the understanding of the skilled person.

[0143] In operation, the visual indication section 1106 moves between two different visible positions when the pre-determined characteristic is detected. Therefore, in thepresent example, the apparatus 1100 has undergone a visual change, which is indicative of the detection of the pre-determined characteristic.

[0144] It will be appreciated that any of the configurations presented in each of Figures 2 (a) -2(g) may be combined with each other to provide further embodiments, in accordance with the understanding of the skilled person.

[0145] Figure 3(a) is a schematic of a specific embodiment of the apparatus 1100 as shown in Figure 2(c), and in accordance with a eighth embodiment of the present disclosure. It will be appreciated that the functionality as described in relation to Figure 3(a) may be applied to any of the other embodiments described herein, in accordance with the understanding of the skilled person.

[0146] In the schematic, a surface of the mounting unit 1104 (for example having the viewing port 1110) has been omitted from the drawing to provide a view of the interior of the mounting unit 1104, to aid in the explanation of the operation of the system.

[0147] In the present embodiment, the mounting unit 1104 comprises a biasing module 1200 that is configured to apply a biasing force to the indicator component 1102. The direction of the biasing force is denoted by an arrow 1202 in the schematic. The mounting unit 1104 further comprises a retaining module 1204 that is configured to hold the indicator component 1102 in the first position, and to release the indicator component 1102 upon detection of the pre-determined characteristic.

[0148] During operation, when the indicator component 1102 is held in the first position, the biasing force does not overcome the opposing force provided by the retaining module 1204, as is shown in the leftmost image. After release of the indicator component 1102 by the retaining module 1204, the opposing force is sufficiently decreased such that the biasing force results in the moving of the indicator component 1102 to the second position, as shown in the rightmost image.1

[0149] Figure 3(b) is a schematic of the apparatus 1100 showing a specific embodiment of the apparatus 1100 of Figure 3(a), and in accordance with a ninth embodiment of the present disclosure.

[0150] In the present embodiment, the biasing module 1200 comprises biasing springs 1206a, 1206b, 1206c, 1206d. It will be appreciated that in further embodiments, the biasing module 1200 may comprise one or more biasing springs. The biasing springs 1206a-1206d are positioned between an edge of the indicator component 1102 and an interior edge of the mounting unit 1204. The biasing springs 1206a-1206d may be referred to as thrust springs.

[0151] The retaining module 1204 comprises one or more retaining portions, with there being two retaining portions 1212a, 1212b in the present example. Each of the retaining portions 1212a, 1212b comprises at least one detection component 1214a, 1214b for detecting the pre-determined characteristic.

[0152] It will be appreciated that the, or each, detection component 1214a, 1214b of the embodiments described herein may be inert in sea water.

[0153] In the present example, each of the retaining portions 1212a, 1212b comprises a retaining spring 1216a, 1216b that holds the indicator component 1102 in the first position (leftmost image). In operation, the detection components 1214a, 1214b react to the pre-determined characteristic and, in response, permits extension of their associated retaining spring 1216a, 1216b. The reaction may, for example, be a chemical reaction. The extensions result in a reduction in the force applied by each of the retaining springs 1216a, 1216b which results in the movement of the indicator component 1102 to the second position (rightmost image).

[0154] In the present embodiment, the retaining portions 1212a, 1212b contact opposing edges of the indicator component 1102.Figure 4(a) is a schematic of a specific embodiment of the apparatus 1100 as shown in Figure 2(d), and in accordance with a tenth embodiment of the present disclosure. In the present embodiment, the apparatus 1100 comprises a handle 1300 for holding the mounting unit 1104.

[0155] It will be appreciated that any of the embodiments described herein may be used with a handle, in accordance with the understanding of the skilled person.

[0156] In the present example, the indicator component 1102 is in the first position and no visual indication sections are visible.

[0157] The combined indicator component 1102 and mounting unit 1104 may be referred to as a “detection cartridge” that is substantially rectangular mounted in the handle.

[0158] In a further embodiment, the mounting unit 1104 may comprise an attachment portion for attaching the apparatus 1100 to a subsea tree.

[0159] In a further embodiment the apparatus 1100 may comprise a stand for standing the apparatus 11100 on the sea floor. The mounting unit 1104 may be coupled to the stand. The apparatus 1100 may, for example, be arranged as shown for the apparatus 500 of Figure 5(a).

[0160] Figure 4(b) is a further schematic of the apparatus 1100 of Figure 4(a). In the Figure 4(b), the indicator component 1102 is in the second position and the indicator component comprises visual indication sections 1106a, 1106b, 1106c. The visual indication section 1106a has past through the orifice 1112, the visual indication section 1106b is visible through the viewing port 1110 and the visual indication section 1106c is visible through the viewing port 1108.

[0161] In summary, the visual indication section 1106a functions as a sliding flag that is retained within the detection cartridge when mounted in the carrier (the handle1300) such that the visual indication section 1106a is not visible prior to detection of the characteristic, such as the detection of a pre-determined chemical.

[0162] Additionally, the body of the detection cartridge has viewing ports 1108, 1110 cut through the assembly to permit visual inspection of the interior, such that when viewed from the outside, for example by an ROV, a single colour is observed (such as white in the present case), prior to detection of the pre-determined characteristic. When the pre-determined characteristic is detected, the visual indication section 1106a is propelled through the orifice 1112 such that itprotrudes beyond the extent of the carrier and becomes visible external to the assembly. Additionally, when in the alert position, the viewing port slots 1108, 1110 align with the respective visual indication sections 1106b, 1106c which may function as coloured strips, thereby creating a striped effect when viewed from the side of the assembly.

[0163] As discussed previously the pre-determined characteristic that is detected may be the presence of a pre-determined chemical, such that during operation, the visual change of the apparatus 1100 as shown in Figure 4(b) occurs when the predetermined chemical is detected in the subsea environment. The pre-determined chemical may be a fluid of interest.

[0164] It will be appreciated that in further embodiments, the number, size, colour, position, pattern etc. of slots and colours can be varied for best effect and visibility.

[0165] Figure 4(c) is a perspective view of the schematic of the apparatus 1100 as shown in Figure 4(a). Figure 4(d) is a perspective view of the schematic of the apparatus 1100 as shown in Figure 4(b).

[0166] Figure 4(e) is a schematic of a specific embodiment of the apparatus 1100 in accordance with a eleventh embodiment of the present disclosure. Figure 4(f) is a schematic of a further specific embodiment of the apparatus 1100 in accordance with a twelfth embodiment of the present disclosure.Figure 4(g) is a schematic of an exploded perspective view of a portion of the handle 1300 as may be used with any of the embodiments described herein in accordance with the understanding of the skilled person. Figure 4(h) is a schematic of a perspective view of the portion of the handle 1300 shown in Figure 4(g).

[0167] Figure 4(i) is an exploded view of a specific embodiment of the mounting unit 1104 comprising three sub-components 1302, 1304, 1306. Figure 4(j) is a schematic of the mounting unit 1104 of Figure 4(i). It can be observed that the component 1304 is sandwiched between the sub-components 1302, 1306 and is arranged to hold the indicator component 1102 within its interior.

[0168] Figure 4(k) is an exploded view schematic of a specific embodiment of the apparatus 1100. Figure 4(1) is a schematic of a perspective view of the apparatus 1100 of Figure 4(k).

[0169] Figure 5(a) is a schematic of a specific embodiment of the apparatus 1100 in accordance with a thirteenth embodiment of the present disclosure. In the schematic, the upper surface of the mounting unit 1104 is displayed as being transparent to provide visibility of the indicator component 1102 and the interior of the mounting unit 1104. In Figure 5(a), the indicator component 1102 is being held in the first position.

[0170] In the present embodiment, the indicator component 1102 comprises an indentation for each of the retaining portions. In the present embodiment, there are two retaining portions 1212a, 1212b and two indentations 1400a, 1400b. Figure 5(b) is a schematic of a zoomed in portion 1401 of Figure 5(a). The indentations may alternatively be referred to as “grooves”.

[0171] Each of the retaining portions 1212a, 1212b comprises a ball bearing 1402a, 1402b. For each of the retaining portions 1212a, 1212b the retaining springs 1216a, 1216b are configured to hold the indicator component 1102 in the first position by pushingtheir respective ball bearings 1402a, 1402b into the respective indentations 1400a, 1400b.

[0172] Each of the retaining portions 1212a, 1212b may have its detection component 1214a, 1214b positioned between the retaining spring 1216a, 1216b and the ball bearing 1402a, 1402b. In operation, each of the detection components 1214a, 1214b reacts to the pre-determined characteristic and permits extension of their respective retaining springs 1216a, 1216b as a result of the reaction.

[0173] In the present example, the retaining portions 1212a, 1212b contact opposing edges of the indicator component 1102.

[0174] In a specific embodiment, each of the retaining portions 1212a, 1212b may comprise a load spreader, such as a washer. A load spreader may be included between the retaining spring 1216a and the detection component 1214a. A load spreader may be included between the retaining spring 1216b and the detection component 1214b. A load spreader may be included between the detection component 1214a and the ball bearing 1402a. A load spreader may be included between the detection component 1214b and the ball bearing 1402b.

[0175] The mounting unit may comprise one or more fluid channels 1404a, 1404b, 1404c, 1404d with each of the fluid channels 1404a, 1404b, 1404c, 1404d being configured to provide a fluid path to one of the detection components 1214a, 1214b. In the present example, the fluid channels 1404a, 1404b provide a fluid path to the detection component 1214a and the fluid channels 1404c, 1404d provide a fluid path to the detection component 1214b. The fluid channels 1404a-1404d function as passages formed in the cartridge body to allow fluid from the subsea environment to envelop the detection components 1214a, 1214b. By optimising the detection components 1214a, 1214b geometry the system can be tuned to react in the shortest possible time.The retaining portions 1212a, 1212b function as two opposing detent assemblies which prevent the indicator component 1102 from moving in response to the biasing springs 1206-1206d prior to the detection of the pre-determined characteristic.

[0176] The indentations 1400a, 1400b that are formed in the edge of the indicator component 1102 each receive one of the ball bearings 1402a, 1402b, with each ball bearing 1402a, 1402b being held by the action of the associated retaining spring 1216a, 1216b.

[0177] The detection components 1214a, 1214b may function as trigger materials that react to one or more specific pre-determined chemical, such that the predetermined characteristic that is detected may be the presence of the predetermined chemical. The pre-determined chemical may be a fluid of interest.

[0178] In a specific embodiment, during operation, upon sufficient exposure to a specific fluid of interest, the detection components 1214a, 1214b degrade thereby lowering the force applied to their respective ball bearings 1402a, 1402b functioning as detents. When the break out force generated by the biasing springs 1206a-1206d exceeds that of the restraining springs 1216a, 1216b, the ball bearings 1402a, 1402 are forced away from the indicator component 1102 and the indicator component 1102 is moved to the second position.

[0179] Figure 5(c) is an alternative schematic of the apparatus 1100 of Figure 5(a) with the biasing springs 1206a-1206d and retaining portions 1212a, 1212b being concealed from view under a portion of the mounting unit 1104. The indentations 1400a, 1404b are also concealed by a portion of the indicator component 1102.

[0180] Figure 5(d) is a perspective view of the apparatus 1100 of Figure 5(a) with the upper surface of the mounting unit 1104 being displayed. Figure 5(e) is an exploded perspective view of the schematic of the apparatus 1100 of Figure 5(d).Figure 5(f) is a schematic of the apparatus 1100 of Figure 5(a) with the indicator component 1102 in the second position. Figure 5(g) is a perspective view of the apparatus 1100 of Figure 5(f) with the upper surface of the mounting unit 1104 being displayed.

[0181] In the present example, the visual indication section 1106a includes no visible marking to distinguish the section 1106a from the rest of the indicator component 1102. The indication of the characteristic of the subsea environment is provided by the movement of the visual indication section 1106a from one visible position to another visible position, such that the extent of the protrusion of the indicator component 1102 provides the indication of the characteristic. For example, the extent of the protrusion of the indicator component 1102 differs from Figure 5(d), when in the first position, to Figure 5(g) when in the second position. It will be appreciated that in further embodiments, the visible indication section 1106a may include visible markings.

[0182] Figure 5(h) is a schematic of a specific embodiment of the apparatus 1100 in accordance with a fourteenth embodiment of the present disclosure. In the schematic, the upper surface of the mounting unit 1104 is displayed as being transparent to provide visibility of the indicator component 1102 and the interior of the mounting unit 1104.

[0183] The embodiment shown in Figure 5(h) is similar to that shown and described in relation to Figures 5(a) to 5(g) and common features share the same reference numerals. Not all reference numerals are included for clarity purposes.

[0184] The embodiment shown in Figure 5(h) differs from that shown in Figures 5(a) to 5(g) in that there is a single detection component 1214 which is positioned centrally to the indicator component 1102 such that it is in-board to the edges of the unit. In particular, the detection component 1214 is positioned within a housing, formed as a cutout 3010 in this embodiment, of the unit. Moreover, the retaining portions and corresponding indentations (reference numerals omitted for clarity) are positionedeither side of the detection component 1214 and within the cutout 3010 such that the grooves are formed in an inner surface of the cutout 3010. As before, in operation, the detection component 1214 reacts to the pre-determined characteristic and permits extension of each of the retaining springs (omitted clarity) as a result of the reaction.

[0185] It will be appreciated that the detection component 1214 may be made up from more than one detection component portion, with the portions being located together to form a single detection component 1214.

[0186] The mounting unit 1104 also includes an inlet 3012 and an outlet 3014 positioned either side of the unit. The inlet 3012 is connected to inlet channels 3016 to provide a first fluid flow from the inlet 3012 to the detection component 1214. The outlet 3014 is connected to outlet channels 3018 to provide a second fluid flow from the detection component 1214 to the outlet 3014. The channels 3016, 3018 function as passages formed in the cartridge body to allow fluid to flow from an outside edge through the in-boarded detection component 1214 and exhaust via the opposite edge, as indicated by the arrows in Figure 5(h).

[0187] The inlet and outlet 3012, 3014 are positioned on the mounting unit 1104 such that they are laterally offset from one another. For example, based on the orientation shown in Figure 5(h), the axis of the inlet 3012 is positioned to the left of the axis of the outlet 3014. Moreover, the inlet and outlet channels 3016, 3018 are laterally offset from the detection component 1214. For example, the inlet channel 3016 that enters the cutout 3010 where the detection component 1214 is located is positioned to the left of the detection component 1214, while the outlet channel 3018 as it exists the cutout 3010 is positioned to the right of the detection component 1215.

[0188] It will be appreciated that the outlet 3014 may instead or additionally be positioned on the front or rear planar face of the unit at or near the positioning of the detection component 1214 such that fluid may exhaust from one or both planar faces.Although not shown, a gathering funnel may be fitted at the inlet in order to better direct the target fluid into the inlet channel.

[0189] Figure 6(a) is a schematic of a specific embodiment of the apparatus 1100 in accordance with a fifteenth embodiment of the present disclosure. In the schematic, the upper surface of the mounting unit 1104 is displayed as being transparent to provide visibility of the indicator component 1102 and the interior of the mounting unit 1104. In Figure 6(a), the indicator component 1102 is being held in the first position. Figure 6(b) is a schematic of the apparatus 1100 of Figure 6(b) with the indicator component 1102 being in the second position.

[0190] Figure 6(c) is a schematic of the apparatus 1100 of Figure 6(a) with the upper surface of the mounting unit 1104 being visible. Figure 6(d) is a perspective view of the apparatus 1100 of Figure 6(c). Figure 6(e) is a further perspective view of the apparatus 1100 of Figure 6(c).

[0191] Figure 7(a) is a schematic of a specific embodiment of the apparatus 1100 in accordance with a sixteenth embodiment of the present disclosure. In Figure 7(a), the indicator component 1102 is in the second position. Figure 7(b) is a perspective view of the apparatus 1100 of Figure 7(a).

[0192] Figure 7(c) is a schematic of a specific embodiment of the apparatus 1100 in accordance with a seventeenth embodiment of the present disclosure. In Figure 7(c), the indicator component 1102 is in the first position. Figure 7(d) is a schematic of the apparatus 1100 of Figure 7(c) with the indicator component 1102 being in the second position.

[0193] Figure 7(e) is an exploded view schematic of the apparatus 1100 of Figure 7(c).

[0194] In the present embodiment, the mounting unit 1104 comprises a plurality of fluid ports 1113. In the present example, the plurality of fluid ports 1113 comprise seven orifices in an upper portion of the mounting unit and seven orifices in a lower portion of the mounting unit 1104.The fluid ports 1113 allow the passage of a fluid of interest from the external environment into the apparatus 1100. The ports 1113 may for example have a fluid path connection to one or more detection components (such as the detection components 1214a, 1214b).

[0195] This means that when the apparatus 1100 is held so the plane of that face is horizontal with respect to the flowing fluid, the fluid can enter and pass to the trigger materials. The fluid channels 1404a-1404d of Figure 5(b) allowthe fluid to enter the apparatus 1100 when it is held vertically over / in a flow.

[0196] Specific embodiments of the apparatus 1100 may comprise fluid ports of the type as shown in Figure 5(b) and / or fluid ports of the type shown in Figure 7(c).

[0197] Figure 8(a) is a schematic of a specific embodiment of the apparatus 1100 in accordance with a eighteenth embodiment of the present disclosure. In the present embodiment, the apparatus 1100 comprises a further indicator component 1700.

[0198] In specific embodiments, the indicator component 1700 may comprise one or more of the features as described in relation to the indicator component 1102, in accordance with the understanding of the skilled person. Furthermore, the mounting unit 1104 may include one or more features for use with the indicator component 1700 as was described in other embodiments for use with the indicator component 1102, in accordance with the skilled person. For example, in the present embodiment, the mounting unit comprises an orifice 1702 and viewing ports 1704, 1706 for use with the indicator component 1700. In the present embodiment, the indicator components 1102, 1700 are in their respective first positions.

[0199] Each of the indicator components 1102, 1700 may be responsive to different predetermined characteristics. For example, the indicator component 1102 may move to its second position and show an “alert” in response to a first pre-determinedchemical, with the indicator component 1700 moving to its second position to show an “alert” in response to a second pre-determined chemical.

[0200] In the present example, the geometry on the alert panels (the viewing ports) is different to help clarify which indicator has been triggered. Specifically, the indicator component 1102 uses circular viewing ports and the indicator component 1700 uses rectangular viewing ports.

[0201] It will be appreciated that in further embodiments, the apparatus 1100 may include additional indicator components that may be sensitive to different pre-determined characteristics.

[0202] Figure 8(b) is a schematic of a specific embodiment of the apparatus 1100 in accordance with a nineteenth embodiment of the present disclosure. In the present embodiment, the indicator component 1102 is in its second position (indicating an “alert”) and the indicator component 1700 is in its first position.

[0203] Figure 8(c) is a schematic of a specific embodiment of the apparatus 1100 in accordance with a twentieth embodiment of the present disclosure. In the present embodiment, the indicator component 1102 is in its first position and the indicator component 1700 is in its second position (indicating an “alert”).

[0204] Figure 8(d) is a schematic of a specific embodiment of the apparatus 1100 in accordance with a twenty first embodiment of the present disclosure. In the present embodiment, the indicator component 1102 is in its second position and the indicator component 1700 is in its second position. In the present example there are two “alerts” provided by the positions of the indication components 1102, 1700.

[0205] Figure 9(a) is a schematic of a specific embodiment of the apparatus 1100 in accordance with a twenty second embodiment of the present disclosure. In the present embodiment, the apparatus 1100 further comprises indicator components 1800, 1802 and a mounting unit 1804. The apparatus 1100 of the presentembodiment may be referred to as a “dual head” assembly due to the inclusion of two mounting units 1104, 1804. In the present example no “alerts” are shown.

[0206] The indicator components 1800, 1802 may function substantially as described for the indicator components 1102, 1700 and may include any of the features described herein in relation to any of the embodiments of the indicator components 1102, 1700, in accordance with the understanding of the skilled person. The mounting unit 1804 may function substantially as described for the mounting unit 1104, and may include any of the features described herein in relation to any of the embodiments of the mounting unit 1104, in accordance with the understanding of the skilled person.

[0207] In further embodiments, the apparatus 1100 may comprise fewer or more indicator components. For example, one or both of the mounting units 1104, 1804 may include additional indicator components.

[0208] Each indicator component may be responsive to a different pre-determined characteristic, in accordance with the understanding of the skilled person. For example, in a specific embodiment, each mounting unit 1104, 1804 may comprise single indicator components and thus provide for the detection and differentiation of two fluids of interest.

[0209] Further embodiments may comprise additional mounting units each having one or more indicator components.

[0210] The mounting unit 1804 may comprise an attachment portion 1806 for coupling with the mounting unit 1104.

[0211] Figure 9(b) is a schematic of the apparatus 1100 of Figure 9(a) with the indicator components 1102, 1700, 1800, 1802 in different positions. In the present example, one alert is indicated by the positioning of the indicator component 1800.Figure 9(c) is a schematic of the apparatus 1100 of Figure 9(b) with the indicator components 1102, 1700, 1800, 1802 in different positions. In the present example, four alerts are shown, as indicated by all indicator components 1102, 1700, 1800, 1802 being in their alert positions.

[0212] It will be appreciated that further embodiments may comprise multiple detection cartridges separated but linked via attachment portions (for example as shown in Figure 9(a)-9(c)) and / or may comprise single integrated detection cartridges having more than one indicator component (for example as shown in Figure 8(a)-8(d)).

[0213] Figure 10(a) is a schematic of a specific embodiment of the apparatus 1100 in accordance with a twenty third embodiment of the present disclosure. Figure 10(b) is a further schematic of the apparatus 1100 of Figure 10(a).

[0214] The apparatus 1100 comprises the indicator component 1102 and the mounting unit 1104. The mounting unit 1104 is configured to hold the indictor component 1102 in the first position, as shown in the leftmost image of Figure 10(a).

[0215] The mounting unit 1104 is further configured to move the indicator component 1102 to the second position in response to the detection of the pre-determined characteristic, as shown in the rightmost image of Figure 11(a).

[0216] In the present example, the visual indication is provided by the rotational motion of the indicator component 1102.

[0217] In a specific embodiment, the indicator component 1102 may be held in place by a retaining spring (not shown) that is permitted to extend when a detection component (not shown) reacts to the pre-determined characteristic. The retaining spring may, for example, be a non-linear spring such as a torsion spring.

[0218] A torsion spring can be used to impart a rotational movement which in turn drives a shaft connected via a gland / seal arrangement to the indicator component1102. This indicator component 1102 may be placed outside the vessel in which the detection occurs and is formed to pivot about one end. The degree of rotation (or lack thereof) may be indicative of the compression of the detection component. Similar to a fuel gauge in a vehicle, the apparatus 1100 can provide an at-a-glance indication of whether the detection component has been degraded by the fluids passed into or through the apparatus 1100.

[0219] The rotating arm (the indicator component 1102) may be controlled by a direct shaft connection through the wall or end cap of a detection vessel, or it can be coupled between internal and external components using a non-contact means, such as magnets. The magnetic approach means that higher internal pressures can be retained by the detection vessel than where a penetration through the wall is required.

[0220] The detection vessel (not shown) may be part of the apparatus 1100 or may be a separate component that the apparatus 1100 is coupled to. The detection vessel may, for example, hold a fluid of interest to pass to the apparatus 1100 for chemical sensing.

[0221] The present embodiment of the apparatus 1100 may be referred to as a “dial indicator” and can be enhanced further by the addition of intermediate gearing such that the degree of rotation of the indicator component 1102 is amplified to make visual assessment easier.

[0222] In a specific embodiment the indicator component 1102 may be set in a recess formed in the end cap of the detection vessel. The recess may take any form but would typically be a quarter or semi-circle in profile with a recessed depth in excess of the thickness of the indicator component 1102. Visual elements, such as by engraving, around this recessed feature can indicate the degree of movement. This might be expressed in terms of actual distance (such as mm) or as a percentage. Thus 0 % would indicate zero movement whereas 100 % wouldindicate complete degradation of the detection material and full displacement of the compressive element (for example, the torsion spring).

[0223] The apparatus 1100 may comprise a partially, or fully, transparent cover (such as may be formed from polycarbonate) that is fitted over the dial indicator to protect it from external forces whilst allowing visualisation of the arm.

[0224] The apparatus 1100 (including detection elements) may be formed into a single, replaceable unit, for ease of insertion / removal from detection vessels.

[0225] Figure 11(a) is a schematic of a specific embodiment of the apparatus 1100 in accordance with a twenty fourth embodiment of the present disclosure. In the present schematic, the indicator component 1102 is being held in a deactivated position by a retaining pin 2000, prior to use.

[0226] Figure 11(b) is a schematic of the apparatus 1100 of Figure 11(a) where the retaining pin 2000 has been removed and the indicator component 1102 is in the first position prior to the detection of the pre-determined characteristic.

[0227] Figure 11(c) is a schematic of the apparatus 1100 of Figure 11(a) where the indicator component has transitioned to the second position.

[0228] In the present example, the visual indication is provided by the indicator component 1102 moving from the first position to the second position.

[0229] Figure 11(d) is a cross section schematic of the apparatus 1100 of Figure 11(a) with the indicator component 1102 in the deactivated position. Figure 11(e) is a cross section schematic of the apparatus 1100 of Figure 11(b) with the indicator component 1102 in the first position. Figure 11(f) is a cross section schematic of the apparatus 1100 of Figure 11(c) with the indicator component 1102 in the second position.In the present embodiment, the mounting unit 1104 comprises a biasing module 2002 configured to apply a biasing force to the indicator component 1102. The mounting unit 1104 further comprises a retaining module 2004 configured to hold the indicator component 1102 in the first position, and release the indicator component 1102 upon detection of the pre-determined characteristic, such that the biasing force applied by the biasing module 2002 moves the indicator component 1102 to the second position.

[0230] In the present embodiment, the biasing module 2002 comprises a biasing spring 2006. In the present embodiment, the retaining module 2004 comprises a detection component 2008 for detecting the pre-determined characteristic.

[0231] For example, where the pre-determined characteristic is the presence of a predetermined chemical, the detection component 2008 may react to the predetermined chemical. The detection component 2008 may be referred to as a “trigger” or “trigger material”.

[0232] In the present example, and as shown in Figure 11(f) the detection component 2008 has degraded, thereby enabling the biasing force provided by the biasing spring 2006 to push the indicator component 1102 further out of the mounting unit 1104, thereby indicating the presence of the pre-determined chemical.

[0233] The apparatus 1100 may further comprise a thrust plate 2010 to limit the movement of the indicator component 1102.

[0234] Figure 12(a) is a schematic of a specific embodiment of the apparatus 1100 in accordance with a twenty fifth embodiment of the present disclosure. In the present schematic, the indicator component 1102 is in the first position prior to the detection of the pre-determined characteristic.

[0235] Figure 12(b) is a schematic of the apparatus 1100 of Figure 12(a) where the indicator component has transitioned to the second position.In the present example, the visual indication is provided by the indicator component 1102 moving from the first position to the second position.

[0236] Figure 12(c) is a cross section schematic of the apparatus 1100 of Figure 12(a) with the indicator component 1102 in the first position. Figure 12(d) is a cross section schematic of the apparatus 1100 of Figure 12(b) with the indicator component 1102 in the second position.

[0237] The apparatus 1100 may further comprise a protective cage 2012, a radially magnetised ring magnet 2014, an indicating rod magnet 2016, a connecting rod 2018, slots for fluid passage 2020, and a removable end cap 2022.

[0238] In the present example the indicator component 1102 is moved by magnetic field in response to the movement of the ring magnet 2014.

[0239] The embodiments presented in Figures ll(a)-(f) and 12(a)-12(d), may use cartridge-style assemblies whereby everything that is needed to detect / react and provide visual indication or drive secondary action, are handled as a single unit. The reactive portion of the unit (the trigger assembly / carrier, which is the detection component 2008) is disposed within a closed vessel (bottle) that may or may not be pressure retaining. The apparatus 1100 is configured such that it pushes a coloured rod outwards (the indicator component 1102) away from the detection component 2008 and in so doing the rod becomes visible outside the vessel, having previously been flush with the surface of the vessel end cap (or other surface) into which it is secured.

[0240] For a specific embodiment, the detection component 2008 may be a trigger material that degrades when in contact with a specific pre-determined chemical, being a “fluid of interest”.Should the rod (indicator component 1102) become visible it is an indication that the fluid of interest (such as thermogenic gas or liquid hydrocarbon - or another liquid such as water returns containing hydrocarbons) has degraded fluid of interest specific trigger material.

[0241] In a specific embodiment, the cartridge (the apparatus 1100) may be installed in a vessel which has entry and exit ports to allow the passage of fluids (at ambient or higher pressure) to flow through the vessel such that the fluid interacts with the trigger material (the detection component 2008). Such interaction may give rise to physical degradation of the trigger material if the fluid contains the fluid of interest that the fluid of interest specific trigger material has been designed for.

[0242] In the example presented in Figures ll(a)-ll(f) the spring 2006 drives the rod (the indicator component 1102) through the vessel’s housing / end cap, being fitted with such seals as necessary to retain any pressure associated with the monitoring system. This may be referred to as a “penetrating rod example”, which includes the locking pin 2000 to relieve the spring pressure on the trigger material (the detection component 2008) until such time as the unit is ready to be installed. Removal of the locking pin causes the rod to partially extend to signal (with a first colour) that it is monitoring. Subsequent reaction to a fluid of interest causes the remainder of the rod to emerge and display a second coloured portion.

[0243] In the example presented in Figures 12(a)-(d) a non-penetrating rod is moved by magnetic field in response to the movement of a ring magnet.

[0244] The examples presented in Figures ll(a)-ll(f) and Figures 12(a)-12(d) may be used in offshore platforms (including normally unmanned platforms) where there is limited sampling scope. Sampling can be required if a fluid of interest is suspected in either the wellbore or annular spaces of a well. In order to comply with statutory reporting requirements (and to assist with operational management of the well) samples can be taken manually by tapping into the appropriate piping circuit. These samples typically then have to be returned to shore for analysis.Being able to quickly (and locally) determine the presence of a fluid of interest without having to capture gas and send it onshore for laboratory testing is a substantial benefit to operators as existing methods can result in delays of several weeks before results are available.

[0245] A further benefit is reduced risk by not having to fly pressurised bottles from a platform - this is not usually allowed owing to the potential risks of a container failure.

[0246] In further embodiments, the apparatus 1100 may be modified to permit harnessing to other, secondary, equipment such that the passive chemistry detection of a fluid of interest and the subsequent movement of an indicator rod (or magnet) can then give rise to a secondary action such as the activation of a solenoid, or latch or make / break switch, i.e. to initiate a downstream event which might be an electronic signal, hydraulic / pneumatic or other means of conveying a signal or activating a tertiary action.

[0247] Various improvements and modifications may be made to the above without departing from the scope of the disclosure.

Claims

CLAIMS1. An apparatus for indicating a characteristic comprising:a first indicator component; anda mounting unit comprising:i] a biasing module configured to apply a biasing force to the first indicator component; andii] a retaining module comprising one or more retaining portions, each of the one or more retaining portions comprising:a) a retaining spring configured to hold the first indicator component in a first position using a retaining force; and b] a detection component configured to react to a first characteristic, thereby detecting the first characteristic, and as a result of the reaction, to permit extension of the retaining spring which results in a reduction in the retaining force; wherein:the retaining module is configured to release the first indicator component upon detection of the first characteristic as a result of the reduction in the retaining force of each retaining spring, such that the biasing force applied by the biasing module moves the first indicator component to a second position in response to the detection of the first characteristic; andthe apparatus is configured to exhibit a visual change that is observable as a difference in visual appearance when the first indicator component has moved from the first position to the second position, thereby indicating the first characteristic.

2. The apparatus of claim 1, wherein the apparatus is for indicating a characteristic of a subsea environment.

3. The apparatus of claim 2, wherein the visual change from the movement of the first indicator component from the first position to the second position indicates the first characteristic of the subsea environment.

4. The apparatus of any of claim 1 to 3, configured to function on land and / or in a subsea environment.

5. The apparatus of any preceding claim, wherein the first indicator component comprises:one or more first visual indication sections, each of the one or more first visual indication sections being configured to be:i] in a first visible position when the first indicator component is in the first position; andii] in a first concealed position when the first indicator component is in the second position.

6. The apparatus of claim 5, wherein the mounting unit comprises:one or more first viewing ports, each of the one or more first viewing ports being configured to permit visible inspection of one of the first visual indication sections when it is in the first visible position.

7. The apparatus of claim 6, wherein the mounting unit comprises:one or more first orifices, each of the one or more first orifices being configured to permit passage of another one of the first visual indication sections from the first visible position outside the mounting unit to the first concealed position within the mounting unit.

8. The apparatus of claim 7, wherein the mounting unit comprises:one or more first orifices, each of the one or more first orifices being configured to permit passage of one of the first visual indication sections from the first visible position outside the mounting unit to the first concealed position within the mounting unit.

9. The apparatus of any preceding claim, wherein the first indicator component comprises:one or more second visual indication sections, each of the one or more second visual indication sections being configured to be:i] in a second concealed position when the first indicator component is in the first position; andii] in a second visible position when the first indicator component is in the second position.

10. The apparatus of any preceding claim, wherein the first indicator component comprises:one or more third visual indication sections, each of the one or more third visual indication sections being configured to be:i] in a third visible position when the first indicator component is in the first position; andii] in a fourth visible position when the first indicator component is in the second position.

11. The apparatus of claim 10, wherein the mounting unit comprises:one or more third viewing ports, each of the one or more third viewing ports being configured to permit visible inspection of one of the first visual indication sections when it is in the third visible position; andone or more fourth viewing ports, each of the one or more fourth viewing ports being configured to permit visible inspection of the one of the first visual indications sections when it is in the fourth visible position.

12. The apparatus of claims 11, wherein the mounting unit comprises one or more third orifices, each of the one or more third orifices being configured to permit passage of another one of the first visual indication sections from the third visible position to the fourth visible position13. The apparatus of claim 12, wherein for each of the one or more third visual indication sections, one of the third visible position and the fourth visible position iswithin the mounting unit and the other of the third visible position and fourth visible position is outside the mounting unit.

14. The apparatus of claim 10, wherein the mounting unit comprises one or more third orifices, each of the one or more third orifices being configured to permit passage of one of the first visual indication sections from the third visible position to the fourth visible position.

15. The apparatus of any preceding claim, wherein the first indicator component is positioned at least partially within the mounting unit when in use.

16. The apparatus of any preceding claim, wherein the biasing module comprises one or more biasing springs.

17. The apparatus of claim 16, wherein each of the one or more biasing springs is positioned on a first edge of the first indicator component and a first interior edge of the mounting unit.

18. The apparatus of any preceding claim, wherein:the first indicator component comprises an indention for each of the one or more retaining portions;each of the one or more retaining portions comprises a ball bearing; and for each of the one or more retaining portions, the retaining spring is configured to hold the first indicator component in the first position by pushing a ball bearing into one of the indentations.

19. The apparatus of claim 18, wherein:for each of the one or more retaining portions the detection component is positioned between the retaining spring and the ball bearing; andthe detection component is configured to react to the first characteristic, and permit extension of the retaining spring as a result of reacting to the first characteristic.

20. The apparatus of any preceding claim, wherein each of the one or more retaining portions comprises a load spreader.

21. The apparatus of any preceding claim, wherein the mounting unit comprises one or more fluid channels, each of the one or more fluid channels being configured to provide a fluid path to the detection component of one of the one or more retaining portions.

22. The apparatus of any preceding claim, wherein:the retaining module comprises a first retaining portion and a second retaining portion;the first retaining portion is arranged to contact a second edge of the first indicator component and the second retaining portion is arranged to contact a third edge of the first indicator component; andthe second and third edge are opposing sides of the first indicator component.

23. The apparatus of any preceding claim, wherein for each of the one or more retaining portions, the detection component is configured to chemically react upon detection of the first characteristic.

24. The apparatus of any preceding claim, wherein the first characteristic is the presence of a first pre-determined chemical.

25. The apparatus of claim 24, wherein the first pre-determined chemical comprises a tracer fluid, and / or a thermogenic gas, and / or a biogenic gas, and / or methane, and / or a hydrocarbon, and / or methanol, and / or monoethylene glycol, and / or a control fluid, and / or carbon dioxide.

26. The apparatus of claim 24 or claim 25, configured to monitor the integrity of a subsea well or a fluid sequestration site by indicating that the first pre-determined chemical has been detected.

27. The apparatus of any preceding claim comprising:a second indicator component; wherein:the mounting unit is configured to:hold the second indicator component in a third position; and move the second indicator component to a fourth position in response to the detection of a second characteristic; wherein:the apparatus is configured to exhibit a second visual change when the second indicator component moves from the third position to the fourth position, thereby indicating the second characteristic.

28. The apparatus of any preceding claim, comprising a handle wherein the mounting unit is coupled to the handle.

29. The apparatus of any preceding claim, wherein the mounting unit comprises a first attachment portion for attaching the apparatus to a subsea tree.

30. The apparatus of any preceding claim, comprising a stand for standing the apparatus on the sea floor, wherein the mounting unit is coupled to the stand.

31. The apparatus of any preceding claim configured to trigger a secondary action when the first indicator component moves from the first position to the second position.

32. The apparatus of claim 31, wherein the secondary action is one or more of activating an audible indicator, transmitting a wireless signal, initiating an activation sequence of ordnance, controlling an electrical or magnetic switch, starting a mechanical device or a hydraulic device or a stored energy device,releasing a buoy or a beacon, opening or closing a valve, activating a solenoid, incrementing a counter, starting or stopping a timer and / or a clock.

33. A method of indicating a characteristic using the apparatus of any preceding claim.

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