AU2015205836A1 - A well comprising a safety mechanism and sensors - Google Patents

Abstract

A Well 5 A well (10) comprsing: (a) a safety mechanism (16,25), the safety mechanism comprising: (i) an obstructing member (412,414) moveable between a first position where fluid flow is permitted, and a second positon where fluid flow is restricted; (Ii) a movement mechanism (416,418); (iii) and a wireless receiver (360), adapted to receive a wireless signal; wherein the movement mechanism (416,418) is operable to move 10 the obstructing member (412,414) from one of the first and second positions to the ote r of the frst sand second positions in response to a change in the signaI being received by the wireless receiver (360); (b) sensors to detect a parameter in the well (10), in the vicinity of the safety mechanism (16,25); wherein a sensor is provided above and a sensor is provided below the safety mechanism (16,25), Embodiments of 1$ the invention have acoustic and/or electromagnetic receivers or transceivers. Figure 1 $ 0 2-2 "N/2b <12 j 20 / Fig. I

Description

A WELL COMPRISING A SAFETY MECHANISM AND SENSORS This invention relates to a safety mechanism, such as a vaive, sleeve, packder 5 orn1ug, for a well; a wel comprising the safety mechanism; and methods to improve the safety of wells; particularly but not exclusively subsea hydrocarbon wells, In recent years. oil and gas has been recovered'from subsea wells in very 10 deep water, of the order of over 1km. This poses many technical problems in driling, securing, extracing and abandoning wells in such depths. In the event of a fadure in the integrity of the well, wellhead apparatus control systems are known to shut the well off to prevent dangerous blowout, or 1. significant hydrocarbon loss front the well. Blow-out-preventers (BOPs) are situated at the top of subsea wells, at the seabed, and can be activated frorn a control room to shut the w, or may be adapted to detect a blow-out and shut automatically, Should thi far, a remotely operated vehicle (ROV) can direct activate the BOP a he seabed to shut the well. 20 In a completed well, rather than a BOP, a ristma& tree a provided at the ton of the well and a subsurface safety valve (SSV) is normally added, "downhe in the wel. The SSV is normally activated to close and shut the well if it loses communication with the controlling platform, rig or vessel, Despite these known safety controls, accidents still occur and a recent example is the disastrous biow-out from such a subsea well in the Gulf of Mexico, causing a massive explosion resulting in loss of life, loss of the rig and a significant and sustained escape of oi! into the Guif of Mexico, threatenrng wildife and marine industries, Whilst the specific causes of the disaster are, at present, unclear, some 5 aspects can be observed: an Emergency Dis-connect System (EDS) controled from the rig failed to seal and disconnect the vessel from the well; a dead-rnanAMF system at the seabed failed to seal the well; subsequent Remotely Operated Vehicle (ROV) intervention also failed to activate the safety mechanisms on the BOP. GCarly the conventional systems focused 10 primarily on the blow-out-preventer did not activate at the time of the blow-cut and also failed to stem the tide of oil into the sea after control communication was lost with the rig. Thus there is a need to irnprove the safety of oil weks especiaiiy those 15 situated in deep water regions, Given the difficulty in communicating and controlling downhoie tools (that is tools in the well), especially where communications are severed, one might consider the provision of a further shut off mechanism with the SOP situated 20 at the seabed. However the inventors of the present invention have roted that the addition of more equipment at this point vil be extremely difficult because it wil increase the size and height of the components placed at this point, which immediately prior to installation, will be difficult for rigs to accommodate, Moreover, whilst this would add a further protective measure, 25 it is largely the same concept as the existing safety systems, indeed, increasing the complexity of the control systems to support these additional features may potenially have a detrimental impact on reliabilily of the over-ali system rather than increasing the level of safety provided, 3 In the case of adding a further conventional control mechanism for devices, such as a valve, or sensor downhole; the inventors of the present invention also note imitations since, in The event of a blow-out, the ability to function S these devices may be lost due to the inability to fluctuate pressure to control pressure activated devices, or due to the loss of control lines, Thus it is difficult for a skilled person to design a further safety system which can practially add to the safety systems already provided in ol wells, 10P An object of the present invention is to mitigate problems with the prior art, and preferably to improve the ostyf wells. According to a first aspect of the present invention there is provided a safety 15 mechanism compsing: an obstructing member moveable between, nornally from, a first position where fluid flow is permitted, and, normally to, a second position where fluid flow is restricted; a movement mechanism; 20 and a wireless receiver normally a transceiver, adapted to receive, and normally transmit, a wireless signal; wherein the movement mechanism is operable to move the obstructing member from one of the first ano second positions to the other of the first and second positons in response to a change in the signal being received by the 25 wireless transceiver, The obstructing member can in certain embodiments therefore start at either the first or second positions.

The transceiver, where it provided, is normally a single device with a receiver functionaity and a transmitter functionality; but in principle a separate receiver and a separate trnsmitter device may be provided, These are nonetheless 5 considered to be a transceiver as described herein when the are provided together at one location. Relays and repeaters may be provided to facilitate transmission of the wireless slgnas -firom one location to another, The invertion also provides a well comprising at least one safety mechanism according to the first aspect of e invention. Typicaly the well has a welhtad, 1S Thus the present invention provides a significant benefit in that it can move, norrmally shut, an obstructing member, such as a valve, packer, sleeve or plug in response to a wretess signaL Significanidy this is independent of the provision of control ines, such as hydraulic or electic nes, between a weli 20 and a welihead apparatus, for example the BOP, Thus in the event of a disastrous blowout or explosion, a wireless signal can be sNt to the valve merely by contacting the wellhead apparatus typically at the top of the well with a wireless transmitter, which will send the appropriate signal For certain embodiments the wireless transmitter may be mounted onto the welihead 25 apparatus. indeed this can be achieved even if the wellhead apparatus has suffered extensive damage. and/or the hydrailc, electric, and other control lines have been damaged and the conventional safety systems have lost ail functionality, since the wireless signal requires no intact control lines in rder to shut off the valve, Thus this removes the present dependence on a functioning BOP/welihead apparatus to prevent the egress of oil, gas or other wet fluids into the sea, 5 in certain embodiments the transmitter ray be provided as part of a wethead apparatus. Wellhead apparatus as used herein includes but is not limited to a weihead, tubing and/or casing hanger, a BOP, wirelineicoited tubing ubdoator, guid 10 base, weti tree, tree frame, well cap, dust cap and/or wel canopy. Typicaly the welihead provides a sealing interface at the top of the borehole, Typically any piece of equipment or apparatus at or up to 20 - 30m above the wedihead can te considered for the present purposes as wellhead apparatus, 15 Said change in the signal" can be a different signal received, or may be receiving the control signal where no control signal was previously received and may aiso be loss of a signal where one was previously received. Thus in the latter case the safety mechanism may be adapted to operate when 20 wireless communication is lost which may occur as a consequence of an emergency situation, rather then necessarily requiring a control signal positively sent to operate the safety mechanism., Indeed the invention more generally provides a transceiver configured to 25 activate and send signals after an emergency situation has occurred as defined herein, 6 in preferred embodiments the transceiver is an acoustic transceiver and the control signal is an acoustc control signal, in alternative embodiments, the transceiver may be an electromagnetc transceiver, and the signal an electromagnetic signaL Combinations may be provided - for example part of 5 the distance may be travelled by an acoutic signal, part by an electromagnetic signal, part by an electric cable, and/or part from a fibre optic cabe; l wth trans as necessary. The acoustic signals may be sent through elongate members or through well 0 fluid, or a combination of both. To send acoustic signals through the fluid, a pressure puLser or mud pulsr may be used. Preferably the obstrucing member rnoves from the first to the second position. 15 Preferably the safety mecharnsm incorporates a battery, The safety mechanism is typically deployed subsea. 20 The transceiver composes a transmitter end a receiver, The provision of a transmitter alows sionais to be sent from the safety mechanism to a controler, such as acknowledgement of a control signal or confirmation of activation. 25 The safety mechanisn may be provided on a drill string, completion string, casing string or any other elongate member or on a sub-assembIy within a cased or unused section of the well, The safety mechanism may be used in the same well as a BOP or a welihead, tree, or welkcap and may be provided in addition to a conventzonal subsurface safety valve, Typically a piuraity of safety mechanisms are provided. The transceiver may be spaced apart from the movement mechanismn and connected by conventional means such as hydraulic line or electric cable. This ajlows the wireless signa to be transmitted over a smaer distance. For example the wiriess signal can be transmitted from the welhead apparatus t to a Iransceiver up to 100m, sorneimea less than 50m, or less than 20m below the top of the well which is connected though hydraulics or electric cabling to the obstructing member, This allows the safety mechanism in accordance with the present invention to operate even when the wellhead, wedlheadi apparatus or the top 100m, 50m or 20m of the well is damaged and 15 control lines therein broken. Thus the benefits of embodiments can be focused on a particular areas. Accordingv embodiments of the present nvention can be combined with fluid andlor electric control systems. Preferably a sensor is provided to detec t t a parmeter in the well, preferably in 20 the viinity of the safety mechanism, Thus such sensors can provide important information on the environment in al parts of the well especay aron'd the safety mechanism and the data from the sensors may provide information to an operator of an emergency 25 situation that may be occurring or about to occur and may need intervention to mitigate the emergency situation.

8 Preferably the inforrnation is retrieved wirelessly, although other means, such as data cables, may be used, Preferably therefore ie safety mechanism comprises a wireless transmitter, and more preferably a wireless transceiver, 5 The sensors may sense any parameter and so be any type of sensor including but not necessarily limited to temperature, acceleration, vibration, torque, movement, motion, cement integrity, pressure, direction and incnation, load, Various tubuaasing angleerosion, radiation, ncise, magnetism. seimic movemets, stresses and strains on 10 tubular/casings including twisting, shearing, compressions, expansion buckling and any form of deformation: chemical or radioactive tracer detection: fluid identification such as hydrate, wax and sand production; and fluid properties such as (but not limited to) flow, density, water cut, pH end viscosity, The sensors may be imaging, mapping and/or scanning devices 25 such as, but not limited to, camera, video, infra-red, magnetic resonance. acoustic, ultra-sound, electrical, optical, impedance and capacitance. Furthermore the sensors may be adapted to induce the signal or parameter detected by the incorporation of suitable transmitters and mechanisms. The sensors may also sense the status af equipment within the well, for 20 example valve position or motor rotation. The wireless transcever may be incorporated within the sensor, valve or safety mechanism or may be independent from it and connected thereto. The sensors may be incorporated directly in the equipment comprising the 25 transmitters or may transfer data to said equipment using cables or short range wireless (eMg inductive) communication techniques Short range is typically iess than 5m apart, often less than 3m apart and indeed may be less than 1m apart.

The sto operate only in an emergency situation but can also provide details on different parazmeterrs at ary tirme. The sensorcan e useful for cement tests, testing pressures on either side of packers, sleeves, 5 valves or obstrucdons and we!!head pressure tests and generally for well information and ncnitoing from any location in the well The wireless signals may be retroactively, that is after an emergency situation has occurred, for example after a blow out 0 Typically the sensors can store data for later retrieval and are capable of transmitting it, The safety mechanism may be adapted to move the obstructing member to/from the first position from/to the second position automatically in response 5 to a parameter detected by the sensor. Thus at a certain "trip point" he safety mechanism can close the well, if for exam pie, it detects a parameter indicatve of unusual data or an emergency situation. Preferably the safety mechanism is adapted to function in such a manner in response to a plurality of different parameters all detecting unusual data, thus suggesting an 20 emergency situation, The parameter may be any parameter detected by the sensor, such as pressure, temperature, flow, noise, or indeed the absence of flow or noise for example, Such safety mechanisms are particularly useful during al1 phases when a 25 BOP is in use and especially during non-drilling phases when a BOP is in use.

10 Preferably the trip point can be varied by sending instructions to a receiver coupled to (not necessary physicaly connected thereto) or integral with, the sensors and/or safety mechanis.n Such embodiments can be of great benefit to the operator, since the different operations downhoie can naturally 5 experience different parameters which may Lie safe in one phase but indicative of an emergency siuatin another p Raher han setting the trip point at the maximurn safety level for all phases, they can be changed by communications including wireless communication for the different phases. For example, during a during phase the vibration sensed would be expected 10 to be relatively high compared to other phases. Sensing vibration to the same exten o i Other aces may be indicative of an emergency situation and the safety mechanism instructed to change their trip point after the drilling phase, 1 5 Fr certain embodiments, a sensor is provided above and below the safety mechanisms and can thus mnitor differential parameters in these psitions which can in turn elicit information on the safety of the we|L in particular any pressure differential detected across an activated safety mechanism would be of particular use in assessing the safety of the well especially on occaaons 20 where a controlling surface vessel moves away for a period of time and then retums, Sensors and/or transceivers rsy also be provided in casing annuli. 25 in use, an operator can react to any abnormal and potentially dangerous occurrence which the sensors detect. This can be a variety of different parameters incudling pressure, temperature and alo others lik e stress and I1 i on pipes or any other parameters/sensors referred to herein but not bmited to those, Moreover with a plurality of sensors, the data may provide a profile of the . pararmeters (for example, pressure/temperature) along the casing and so aid identification where the loss of integrity has occurred, eg. whether the casing, casing cement, fcat ectar or seal assembly have failed tc isolate the reservoir or weit Such information can allow the operator to react in a quick, safe and etflcent manner; alternatively the safety mechanism can be adapted 10 to activate in response to certain detected.i parameters or combination of parameters, especially where two or three parameters are showi ng unusual values. Such a system may be activated in response to an emergency situation, 1S Thus the invention provides a method of inhibiting fluid flow from a well in an emergency situation, the method composing: in the event of an emergency, sending a wireless signal into the well to a safety mechanism according to the first aspect of the invention, 20 Preferred and other optional features of the previous enodiment are preferred and optional features of the method according to the invention immediately above, 25 An emergency or emergency situation is where uncontroded fluid flow occurs or is expected to occur, from a wel; where an unintended explosion occurs or there is an unacceptable risk that it may occur, where significant structural damage of the well integrity is occuning or there is an unacceptable risk that it 12 may occur, or where human life, or the environment is in danger, or there is an unacceptable risk that it maybe in danger. These dangers and risks may be caused by a number of factors, such as the well conditions, as well as other factors, such as severe weather. Thus normally an emergency situation is one where at least one of a BOP and subsurface safety valve would be attempted to be activated, especially before/during or after an uncontrolled event in a well, 80 FUrthermore, normally an emergency situation according to the present invention is one defined as the least, more or most severe accordingly to the IADAC Deepwater Well Control Guide!!nes, Third Printing cluding Supplement 2000, section 4,I2, Thus averts which relate to kick control ray be regarded as an emergency situation according to the present 15 invention, and especijAy events relating to an underground blowout are regarded as an emergency situation according to the present invention, and even more especially events relating to a loss of control of the well at the sea 'oor (if a subsea well) or the surface is even more especially an ernerency according to the present invention, Methods in accordance with the present invention may also be conducted after said emergency and so may be performed in response thereto, acting reroactvely, 25 The method may be provided during all stages of the drilling, cementing, development, completion, operation, suspension and abandonment of the well. Preferably the method is provided during a phase where a BOP is provided on the weli Optionally the method is conducted during operations on the well when attempts have been made to activate the BOR During these phases, embodiments of the present invention are partiudarly 5 usefRu because the pvision of physical control lires dung these phases would obstruct the many wel operations occurring at this ime; and indeed the accepted practice is to avoid as much as possible installing devices which require communication for this reason, Embodiments of the present invention go against this practice and overcome the disadvantages by providing 10 wireless communications, Thus an advantage of embodiments of this invention is that they enable the use of a safety valve or barrier in situations where conventional safety valves or narriers could not, or would not, normally be deployed, 15 The safety mechanism may comprise a valve, preferably a bail or flapper valve, preferably the valve may incorporate a mechanical over-rid.e controlled, for example, by pressure. wireline, or coiled tubing or other intervention methods, The valve may incorporate a 'pump through' facility to permit flow in one director., 0 The obstructing member of the safety mechanism may be a sleeve. Optionally the safety mechanism may be actuated directly using a motor but alternatively or additionally may be adapted to actuate using stored pressure, 25 Or preferably using well pressure acting against an atmospheric chamber, optionally used in conjunction with a spring actuator, The safety mechanism may inoorate components which are replaceable, or incorporate key parts, such as batteries, or valve bodies which are replaceable without removing the whole component from the well This can be achieved using methods such as side-pockets or replaceable inserts, 5 using convenional methods such as wireline or coied-tubng. In order to retrieve data from the sensors and/or actuate the safety mechanism, one option is to deploy a probe, A variety of means may be used to deploy the probe, such as an lectrc line, S"ik line wire, coiled 1) tubing, pipe or any other elongate member, Such a probe could alternatively or additional be adopted to send signals, Indeed such a probe may be deployed into a casing annulus if required, In other embodiments, the wireless signal may be sent from a device 5 provided at the weLihead aparatus or proximate thereto, that is normally within 300rn, In one embodiment wireless signals can be sent fr a platform, optionally with wireless repeaters provided on risers and/or downhole. For other embodiments, the wireless signals can he sent from the seabed weilhead apparatus, after receiving sonar signals from the surface or 20 from an RO, In other embodients, the wireless signals can be sent from the weilhead apparatus after receiving a satellite signals from another location. Furthermore if the welhead is a seabed welhead. the wireless signals can be then sent from the seabed wellhead apparatus, after receiving sonar signals, which had been triggered/activated after receving a satellite 25 signal from another location. The surface or surface facility may be fir example a nearby production facility standby or supply vessel ora buoy.

15 Thus the device comprises a wireless transmitter, or transceiver and creferabiv also comprises a sonar receiver, to receive signals from a surface facility and especially a sonar transoever so that it can communicate two-way 5 with the surface facility. For certain embodiments an electric line may be run into a well and the wireless transcvrzatched towards one end of the line. In other embodiments the signal may be sent from an ROV via a hot-stab connection or via a sonar signal from the ROV, 10 Therefore the invention also provides a device, in use fitted or retro-fitted to a top of a well, comprising a wireless transmitter and a sonar receiver; especialy for use in an emergency situation, The device is relatively small typically being less. than im preferably less 15 than 0,25 mY especially less that 0,10 nnand so can be easily landed on the wedhead apparatus. The resuiting physical contact between the wellhead apparatus and the device provides a connection to the well for transmission of the wireless signal. in alternative embodiments the device is built into the wellhead apparatus, which is often at the seabed but may be on land for a 20 land weL Thus such devices also operate tirelessly and do not require physical communIcation between the wellhead apparatus and a controlling station, such as a vessel or rig, 25 Embodiments of the invention aiso include a satellite device comprising a sonar transceiver and a satellite communication device, Such embodiments can communicate with the well, such as with said device at the welihead apparatus in accordance with a previous aspect of the invention, and reay signals onwards via satellite, The satellite device may be provided on a rg or vessel or a buoy. 5 Thus according to one aspect of the invention there is provided a wel apparatus comprising a well and a satellite device comprising a satelIite communication mechanism, and a sonar, the device configured to relay information received trn the sonar by satelte, 10 Preferably the device is independent of the rig, for example it may be provided on a buoy. Thus in the event that the rig is lost, the buoy may relay a control signal from a satellite to the wel to shut down the we in a further embodiment the device at 'he welhead apparatus may be wired -5 to a surface or remote facility, Preferably however, the device is provided with further wireless communication options for communication with the surface facility. Typically the device has batteries to permit operation in tihe event of damage to the cable. 20 The safety mechanism may comprise a subsurface safety valve, optionaly of known type, along with a wireless transceiver, In alternative embodiments, the safety mechanism comprises a packer and an expansion mechanism. The movement mechanism causes the expansion 25 mechanism to activate which expands the packer ano so moving the packer frm said first position to said second position.

17 Thus according to a further aspect of the present invention there is provided a packer aparatus comnprising a packer and an activation mechanism, the activation mechanism comprising an expansion mechanism for expanding the packer and a wireless transceiver adapted to receive a wireless control signed! 5 and control the activation mechanism., The wireless signal is preferably an acoustic signal and may travel through elongate members and/or well fluid 10 Alternatively the wireless signal may be an electromagnetic or any other wireless signal or any combination of that and acoustic, References throughout to "expanding' and "expansion mechansms" etc include expanding a packer by compression of an elastomeric element and/or 15 inflating a cac'ker and inflation mechanisms etc and/or explosive activation with expAosive mechanisms, or actuation of a swell mechanism by exposure of a sweilable element to an activating fluid, such as water r The packer apparatus may be provided downhole in any suitable location. 20 such as on a drill string or production tubing and, surprisingly in a casing annulus between two different casing strings, or between the casing and formation or on a sub-assembly within a cased or uncased section of the weit In use after depicyment and wireless activation downhole according to the 25 present invention, the packer may be provided in the expanded state to provide a further barrier against fluid movement therepast, especially those provided con an cuter face of an elongate member in a wet. Those between 38 casing and a drill string/production tubing, are preerably reatve to an ernergeny siotuatoi that is unexpanded. Thus the invention also provides a well apparatus comprising; 5 a plurality of casing stings; a packer apparatus provided on one of the casing strings: the packer apparatus comprising a wireless transceiver, and adapted to expand in response to a change in a wireless signal in order to restrict flow of fluid through an annuius between said casing string and an adjacent 10 elongate member. As noted above, the packer may be provided in use in the expanded contguration and act as a permanent banner to resists fluid flow or may be pmvided in the unexpended configuration and activated as required, for 1$ example in response to an emergency situation. Moreover the packer may be adapted to move from an expanded configuration, corresponding to the second position of the safety rechanisrm where fluid flow is restricted (normally blocked) and retract to the first position where fluid flow is permitted, 2>0 The adjacent elongate member may be anMother of the casing strings or may be adrill pipe or may be production t ubing, The invention also provides a packer as described herein for uise on a 23 production strirn in an emergency situation, For example in a gas lift operation the packer may be provided on the production tubing and activated oniv in the event of an emergency.

19 Typically tie packer is provided as a permanent barrier when the adjacent member is another casing strng, and in the unexpanded configuration when the elongate member is a drill pipe of production tubing that is they remain S unexpanded until they expand in response to an emergency situation. Whilst the packer of the packer apparatus mlay expand in an inward or outward direction, preferably it is adapted to expand in an inward direction, 10 The annulus may be a casing annulus. Thus an advantage of such embodiments is that fluid flow through ar annulus can be inhibite, preferably stopped, by provision of such a packer in an annulus, Normaily fluid does not flow through the casing annulus of a wel 15 and so the skilfled person would not consider placing a packer in this position. However the inventors of the present invention have realized that the casing annulus is a Ilow path through which weI fluid may flow in the event of a well failure and blow out, Such an event may be due to failure of the formation, cement and/or sepis provided with the casing system and wellhead, Preferably a plurality of packer apparatus are provided, Different packer apparatus may be provided in the same or in different annui. Preferably the packer apparatus s/are provided proximate to the top of the 25 wel In thes way the packers can typically inhibit fluid flow above the fault or suspected fault, in the casing. Therefore the packer() may be. provided within 00m of the weilhead, more preferably within r50m, especially within 20m, and ideally within 1m, The packers provided in a ciang annulus may be non-weight packers, that is they do not necessarily have engaging r the pakers may be inlatble or swell types, The casing packers may be nstaled above the cernented-in section of the casing and they thus typically provide an additional barrier to flow of fluids above that traditionally provided by a portion of the wel being cased in. 10 in alternative embodiments the pckera may be Provided on an inner side of the casing adjacent to a cemented in portion of the casing, thus inhibiting a flow path at this Point, whilst the cement inhibits the flow path on the outside portion of the casing. 15 The safety mechanism may be a packer-ike element without a through bore and so in effect function as a well plug or bridge plug. n certain emodarnents. the packer may be provided on a drill string, 20 Thus the invention provides a method of drilling, comprising during a drilling phase providing a drill sting comprising a packer apparatus a defined herein. As drill strings typical rotate and move vertically in a well during a driving 25 phase, a skilled person would not be minded to provide a packer thereon since a packer resists movement. However the inventors of the present invention note that a packer provided thereof can be used in an emergency situation and so provides advantages, .2" Thus the packer may be provided on dril sting, production string, production sub-assembly and may operate in cased or uncased sections of the well 5 The safety mechanis and packers described herein may also have additional means of operation such as hydraulic and/or electric lines. Thus the present invention also provides a method of deploying a safety mechanism according to the pt-sent invention, monitoring the well using dat 10 received from sensors as described herein assocated with the safety mechanism whilst abandoning the well and/or cementing the well and/or suspending the weii. Unless otherwise stated methods and mechanisms of various aspects of the !5 present invention may be used in all phases including drilling, suspension, productiorvinjection. completion and/or abandonment of well operations. The wireless signal for all embodiments ia preferably an acoustic signal although may be an electromagnetic or any other signal or combination f 20 signals. Preferably the acoustic communications include Frequency Shift Keying ((FSK) and/or Phase Shift Keying (PSK) modulation methods, and/or more advanced derivatives of these methods, such as Quadrature Phase Shift 25 Keying (QPSK} or Quadrature Amplitude Modulation (0AM), and preferably inoprtn Spread Spectrum Techniques. Typically they are adapted to automaticailv tune acoustic signalling frequencies and methods to suit well conditions, '2 Embodiments of the present invention may be used for onshore welLs as wel as offshore wells, 5 An advantage of certain embodiments is that the acoustic signals can travel up and down different strings and can move fromn to another, Thus near travel of the signal is not reqdred. Direct route devices thus can be lost and a signal can still successfully be received indirectly, The signal can also be combined with other wired and wireless communcaton systems and 10 signals and does not have to travel the whole distance acoustically, Any aspect or embodiment of the present invention can be combined with any other aspect of embodiment mutat x mutandi. 15 An embodiment of the present invention will now be described, by way of example orly, and with reference to the accompanying figures in which: Fig, Is a diagraranti sec tonal view of a weli in accordance with one apt of the present invention; Fig, 2 is a schematic. dagram of the elecotronics which may be used in 20 a transmitting portion of a safety mechanism of the present invention; Fig, 3 is a schematic diagram of the electronics which may be used in a receiving portion of a safety mechanism of the present invention; and, Fgs, 4a - 4c are seconal views of a casing valve sub in various 25 piositions. Figure 1 shows a well 10 comprising a series of casing strWins 122, 12b, 12c, and 12d and adjacent annual A,BCD between each casing string aInd the string inside thereof with a drii sting 20 provided inside the innermost casing I 2a. is conventional in the art, eac'h asing strings extends further into the well 5 than the adjacent casing string on the outside thereof. Moreover, the lowermost portion of each casing string is cemented in place as it extends below the outer adjacent string. in accordance with one aspect of the present invention, safety packers 1' are 0 provided on the casing above the cemented as well as on the dril string 20, These can he activated acoustically at any time including retroactively ie after the eerency, in order to block fluid flow through h the respective annum Whilst normal operation will not require the activation of such packers, they 15 will provide a barrier to uncontrolled hydrocarbon flow should the casing or other portion of the well control fail Moreover sensors (not shown), in accordance with one aspect of the present invention, are provided above and below said pckers in order to monitor 20 downhole parameters at this point. This can provide information to operators on any unusual parameters and the sealing integrity of the packers) Acoustic relay stations 22 are provided on the drill pipe as wall as various points in the annul to relay acoustic data retrieved from sensors in the well 25 A safety valve 25 is also provided in the drill string 2:0 and this can be activated acousticaly in order to prevent fluid flow through the drill strirg, In such an instance a device (not shown) comprising a sonar receiver and an acoustic transceiver instajIed or later landed at a wellhead apparatus such as a BOP structure 30 at the top of the welt The operator sends a sonar signal from a surface facty 32& whc is converted to an acous tic signal and 5 transmitted into the weU by the device, The subsea valve 25 picks up the acoustic signal aid shuts the well downhoie (rather than at the surface), even if other communication are entirely severed with the BOP, In alternative embltodiments a packer picks up the signal rather than the safety 10 valve 25. The packer can then shut a flowpath eg., an annuius. Thus embodiments of the present invention benefit in that they obviate the sole reliance on seabed/rig floorSbridge SOP control mechanisms. As can be observed by disastrous events in tie Gulf of Mexico in 2010, the control of a u5 wel where the BOP has failed can be extremely difficult and ensuing environmental damage can occur given the uncontrolled leak of hydrocarbons in the environment, Embodiments of the present invention provide a system which reduce the risk of such disastrous events happening and also provide a secondary control mechanir for controlling subsurface safety mechanisms, 20 such assubsurface valves, sleeves, plugs ann/or packers. For certain embodiments a control device is provided on a buoy or vessel separate from a rig. The device comoprises sonar transmitter and a sateHite receiver. The device can therefore receive a signal from a satellite directed 25 from an inland installation, and communicate this to the well in order to shut down the wel; all independent of the rig, in such embodiments, the well can be safely closed down evn in the disastrous event of losing the rig, casing valve sub 400 is shown Figs. 4a - 4c comparing an outer body 404 having a central bore 406 extending out of the body 404 at an inner side through port 408 and an outer side through port 410, A moveable member in the morm of a piston 412 is provided in the bore 406 and can move to seal the 5 Port 408, Simay a second moviab member in the form f a piston 414s provided in the bore 406 and can mo've to sea the port 410. Actuators 416, 418 control the pistons 412, 414 respectively. The casing valve sub 400 is run as part of an overall casing string, such as a 10 casing string 12 shown in Fig. 14 and positioned such that the port 408 faces an inner annulus and the port 410 faces an outer annulus, in use. the pistons 412, 414 can be moved to different positions, as shown in Figs, 4a, 4b and 4c, by the actuators 416 413 in response to wireless signals 15 which have been received, Thus the pressure between the inner and outer annual can be sealed from each other by providing at least one of the pistons 412, 414 over or between the respective ports, 408, 410 as shown in Fig. 4a, 4c. 20 in order to equalise te pressure between the inner and outer annul, the pistons 412, 414 are moved to a position outside of the ports 403, 410 so they do not block them nor block the bore 408 therebetween, as shown in Fig. 4b. The pressures can thus be equa!!sed, 25 Thus such embodiments can be useful in that they provide an opportunity to equalise pressure between two adjacent casino annual if one exceeded a safe pressure and/or i an emergency situation had occurred, 26 The port can then be isolated and pressure monitored to see if pressure is going to buIldup again, Thus. in contrast to for example a rupture disk, where it cannot return to its orgina position, embodiments of the present invention can equahis pressure between casing strings, be reset, and then 5 repeat this procedure again, and for certain embodiments, repeat the procedure indefinitely, In one scenario the pressure in a casing string may build up due to flid flow and thermal expansion. A known rupture disk can resolve problems of i0 excessive pressure, and the welf can continue to function normally However a further occurrence of such excess pressure cannot be deal wiz. Moreover it is sometimes difficult to ascertain whether the excess pressure was caused by such a manageable event or whether it is indicative of a more serious probem especially if repeated occurrences of the excess pressure cannot be 15 detected nor alleviated in ki Own systems. Embodimrents f the present invention mitigate these problems, For some embodiments, a number of different casing subs 401 may be used in one string of casing. Figure 2 shows a transmitting portion 250 of the safety mechanism. The 20 portion 250 comprises a transmitter (not shown) powered by a battery (not shown), a transducer 240 and a thermometer (not shown). An analogue pressure signal generated by the transducer 240 passes to an electronics module 241 in which it is digitised and serially encoded for transmission by a carrier frequency, suitably of 1Hz - 10khz, preferably 1kHz - 10kHz utilizing 25 an FSK modulation technique, The resulting bursts of carrier are applied to a magnetostrictive transducer 242 comprising a colI formed around a core (not shown) whose ends are rigidly fixed to the well bore casing (not shown) at paced locations The digitally coded data is thus transformed into a The trnmttreectronlis module 241 in the press ent embodiment com,-prises a signal condiorlning cirtiut 244, a digitising and encoding circuit 245, and a current driver 246, The details of these circuits may be varied and other suitable COrcuitry may be used. The transue is connected to the current driver 246 and formed round a core 247, Suitably, the core 247 is a arninsted rod of nickel of about 25 mm diameter. The length of the rod is 10 chosen to suit the desired sonic frequency, Figure 3 shows a receiving portion 360 of the safety mechanism. A receiving portion 361 comprises a filter 362 and a transducer 363 connected to an electronic module powdered by a battery (not shown). The filter 362 is a 15 mechanical band-pass filter tuned to the data carrier frequencies, and serves to remove sone of the acoustic noise which could otherwise swamp the electronics. The transducer 363 is a piezoeiectric element. The filter 362 and transducer 363 are mechanically coupled in series, and the combination is riily mounted at its ends to one of the elongated members, such as the 20 tubing or casing: strings (not shown). Thus, the transducer 363 provides an electrical output representative of the sonic data signal Electronic filters 364 and 365 are also provided and the signal may be retransmitted or collated by any suitable means 366 typically of a similar configuration to that shown in Fig,2, 25 An advantage of certain embodiments is that the acoustic signals can travei up and down different strings and can move frnmn one string to another Thus linear travel of the signal is not required. DIrect route devices thus can 28 be lost and a signa can sWti successfully be received indirecty, The signal can aso be combined with other wires and wireless communication systems and does not have to travel the whole stance accustically. 5 Improvements and modifiations may be made without departing from the ScOpe of the invention. Whilst the specific example relates to a subsea weo, other enbodiments may be used on platform or land based wells.

Claims (19)

1. A well comprising; (a) a safety mechanism, the safety mechanism comprising: (i) an obstructing member moveable between a first position where fluid flow is permitted, and a second position where fluid flow is restricted; (ii) a movement mechanism; (iii) and a wireless receiver, adapted to receive a wireless signal; wherein the movement mechanism is operable to move the obstructing member from one of the first and second positions to the other of the first and second positions in response to a change in the signal being received by the wireless receiver; (b) sensors to detect a parameter in the weil, in the vicinity of the safety mechanism ; wherein a sensor is provided above and a sensor is provided below the safety mechanism.

2, A well as claimed in claim 1, wherein the receiver is one of: (i) an acoustic receiver and the signal is an acoustic signal; (ii) an electromagnetic receiver and the signal is an electromagnetic signal; and (iii) an electromagnetic receiver and an acoustic receiver and the signal is transmitted over part of its distance by the electromagnetic receiver and part of its distance by the acoustic receiver.

3. A well as claimed in claim i or claim 2., wherein the wireless receiver is a wireless transceiver.

4 A wel as claimed in any preceding claim, further comprising a subsurface safety valve,

5, A well as claimed in any preceding claim, wherein the sensors detect pressure above and below the safety mechanism.

6. A well as claimed in any preceding claim, wherein the information provided by the sensors is retrieved wireless.

7,. A well as claimed in any preceding claim, wherein the receiver is up to lOm, optionally less then 50m, more optionally less than 20m below the top of the weli. 30

8. A well as claimed in any preceding daim, comprising a casing having a casing sub with the safety mechanism in the form of a valve therein, the valve communicating between an inner and outer side of the casing; wherein the valve is adapted to move from one of the first and second positions to the other of the first and second positions, and then back to the first of the first and second positions,

9. A well as claimed in any preceding claim, further comprising a device which is in use fitted or retro-fitted to a top of the well, comprising a wireless transmitter and a sonar receiver; for use in an emergency situation,

10, A wel as claimed in claim 9, wherein the device is less than irn, less than 0,25 mi especially less that 0.10 mn

11. A wel apparatus comprising a well as claimed in any preceding claim, and a sonar receiver and preferably a sonar transmitter.

12, A well apparatus as claimed in claim 11, wherein a satellite device is provided, the device comprising a sateite communication mechanism and configured to relay information received between the sonar receiver and transmitter and the satelite,

13. A method of inhibiting fluid flow from a well as claimed in any one of claims 1 to 8 or a well apparatus as aimed in claim 11 or 12 in an emergency situation, the method comprsing: in the event of an emergency situation, sending a wireless signal into the well to the safety mechanism.

14. A method as claimed in claim 13, wherein the wireless signal is sent during a phase where a BOP is provided on the well.

15. A method as claimed in claim 13 or claim 14, wherein the wireless signal is sent from a device provided at a wellhead apparatus of the well or proximate thereto

16. A method as claimed in claim 14, wherein the wireless signal is sent from a platform, optionaly with wireless repeaters provided on risers and/or downhole.

17. A method as claimed in any one of claims 13 to 14, wherein the wireless signal is sent from the seabed wellhead apparatus, after receiving sonar signals from a surface installation or an ROV, 31

18. A method as claimed in any one of claims 13 to 14 wherein an ROV connects to the seabed wellhead apparatus and send or receives signals via a hot-stab connection,

19. A method as claimed in daim 13 to 15, wherein the wireless signal is sent from the wellhead apparatus after receiving satelite signals from another location.