NO343795B1 - Position sensor for blowout safety with closing head - Google Patents

Description

The designs described here generally apply to the instrumentation of blowout preventers with a closing head (ram blowout preventers). More specifically, the designs described here apply to direct measurement of the closing head's position, speed and rate of movement in a blowout fuse with a closing head.

Well control is an important aspect of oil and gas exploration. When it e.g. if a well is drilled, safety equipment must be put in place to prevent injury to personnel and destruction of equipment resulting from unexpected events related to the drilling activities.

The process of drilling wells involves penetrating many kinds of geological structures or "layers" below the surface. Occasionally, the borehole will penetrate a layer that has a formation pressure that is considerably higher than the pressure maintained in the borehole. When this happens the well is said to have "got a kick". The pressure increase associated with the kick is generally produced by the inflow of formation fluids (which can be liquid, gas or a combination of these) into the borehole. The relatively high pressure kick tends to propagate from an entry point up the borehole (from a high pressure area to a low pressure area). If the kick is allowed to reach the surface, drilling fluid, well tools and other drilling structures can be blown out of the borehole. Such "blowouts" can cause catastrophic destruction of the drilling equipment (eg, including the drilling rig) and significant injury to, or death of, rig personnel.

Because of the risk of blowouts, devices known as blowout preventers are installed above the wellhead at the surface or on the seabed when deepwater drilling is conducted, to effectively seal off a borehole until active measures can be taken to control the kick. Blowout safeguards can be activated so that kicks are adequately controlled and "circulated out" of the system. There are various types of blowout fuses, most of which are blowout fuses with a closed head, and ring-shaped blowout fuses (including spherical blowout fuses).

Blowout fuses with a closing head typically have a main body and at least a pair of horizontally opposed bonnets. The covers are generally attached to the main body around its circumference, with e.g. bolts. Alternatively, the covers can be attached to the main body with a hinge and bolts so that the cover can be swung aside and provide access for maintenance. Within each cover is a piston-activated closing head. The shut-off heads can either be casing shut-off heads (which when activated are moved to engage and surround drill pipe and well tools to seal the borehole), cut-off valves (which when activated are moved to engage and physically cut off possible drill pipe or well tools in the bore hole ) or blind valves (which when activated seal the hole like sluice valves).

The shut-off heads are typically placed opposite each other and whether they are casing heads, cut-off valves or blind valves, they typically seal against each other near the center of the borehole with the aim of sealing the borehole completely.

Closure heads are generally manufactured from steel and fitted with elastomeric components on the sealing surfaces. Sealing head blocks are available in a variety of configurations that allow them to seal a borehole. Casing heads typically have a circular cutout in the center, matching the diameter of the pipe in the hole, to seal the well when the pipe is in the hole, but these casing heads only seal a limited range of pipe diameters effectively. Closing heads for variable border diameters are designed to seal a larger value range of pipe diameters. The various shut-off blocks can also be swapped into blowout preventers, allowing well operators to optimize the blowout preventer configuration for the particular hole section or operation in progress. Examples of blowout fuses of the closed head type are described in US patent no. 6554247, 6 244560, 5897094, 5655745 and 4647002, each of which is included here as a reference.

Knowledge of well conditions is extremely important to maintain correct operation and anticipate future problems with the well. Based on these parameters, a well can be more effectively monitored, so that safe conditions can be maintained. When an unsafe situation is detected, the well can also be shut down in the right way, either manually or automatically. Pressure and temperature transducers in blowout fuse cavities can indicate or predict unsafe conditions. These and other signals can be presented as control signals on a control console used by a well operator. The operator can e.g. influence the well conditions by regulating the rotation speed of the drill pipe, the downward pressure on the drill bit and the circulation pumps for the drilling fluid. When it is desired to close the blowout fuse's closing head, it is useful for the operator to have accurate knowledge of where each closing head is positioned.

A device which has been used in the past to develop a signal which gives an indication of the relative position of components located in a closed housing (not necessarily a blowout protection housing) is a potentiometric transducer. Such a device uses one or more sensors which are subject to wear and inaccuracies in the presence of a harsh environment. Furthermore, such sensors are exposed to being lifted from the surface by whatever is being tracked, which causes inaccuracies. Also, loss of driving force often causes distorted readings because these devices work incrementally by adding or subtracting values relating to specific turns or segments of wire relative to a previous value. Furthermore, devices such as these are notoriously poor high-speed devices. Thus, potentiometric measurement will not be useful with respect to accurately determining the position parameter of a closing head movement. Additionally, potentiometric transducers are not suitable for use in high-speed applications, making them of little or no use in closed-head monitoring applications.

Incrementally measuring devices which only measure intermediate movements have the additional weakness that they must be reset to the baseline in the event of a failure of the power supply, while at the same time they do not provide the precision that results from continuous measurement.

In order to improve the accuracy of measuring the location of closure heads, magnetostrictive sensors have been used to monitor and/or control the position of closure heads. As described in US patent no. 5320325 and 5407172, which is hereby included as a reference, the closing head's piston driver arm is placed parallel to a stationary, magnetisable waveguide tube. A magnet assembly surrounds the waveguide tube and is attached to a support arm attached to the end of the piston.

In US patent no. 7023199, 7121185 and 6509733, a magnetostrictive sensor is mounted in the internal opening of a sensor port. This sensor has a pressure tube which extends into the internal cavity of the cylindrical body and is telescopically received in a passage in the rod in a piston and rod assembly.

The positioning of the magnetostrictive sensors in each of the above-mentioned patents is far from optimal. Because the sensor according to e.g. US patent no. 7023199 extends into the cavity in the cylindrical main part, maintenance to be carried out on the sensor unit necessarily requires that the closing head is not in operation. Attaching the sensor and magnets using a support arm according to US Patent No. 5320325, although they do not invade the cavity of the cylindrical main body, can lead to inaccurate measurement of the closing head position and increase the cost of the production of closing head blowout fuses.

It is therefore an object of the present invention to provide an improved device for accurately measuring the location or position of a closing head or closing head piston in a blowout fuse.

Accordingly, there is a need for an improved device for accurately measuring the location or position of a closing head or closing head piston in a blowout fuse.

The present invention provides a method for monitoring a cylinder pressure exerted on closing heads in a blowout fuse, the method comprising that a relative position of the closing heads in the blowout fuse is sensed with a magnetostrictive sensor, signals are sent from the magnetostrictive sensor to a data capture device, a cylinder pressure exerted on the closing heads is sensed with a pressure sensing device, signals are sent from the pressure sensing device to the data capture device, and the sensed cylinder pressure is recorded as a function of the sensed relative position with the data capture device.

In another aspect, the present description applies to a method for testing components in a blowout fuse, which includes that a cycle test of the blowout fuse is carried out, whereby a cylinder pressure exerted on closing heads in the blowout fuse in selected positions during the cycle test is sensed and recorded, and a closing head position is sensed and recorded with a magnetostrictive sensor during the cycle test.

In another aspect, the present description applies to a method for determining the movement of a wellhead component, and which comprises that a relative position of the wellhead component is sensed with a magnetostrictive sensor over a selected time interval, a signal is sent from the magnetostrictive sensor to a data capture device, the relative position of the wellhead component is recorded with the data capture device in relation to the selected time interval and the recorded position of the wellhead component is compared with operational data to determine whether the relative position is desirable.

In another aspect, the present disclosure relates to a closure head type blowout preventer, which comprises a main body, a vertical bore through the body, a horizontal bore through the body intersecting the vertical bore and a pair of closure head units arranged in the horizontal bore on opposite sides of the body, and wherein the closing head units are adapted for controlled lateral movement to and from the vertical bore, each closing head unit comprising a hydraulic piston connected at a first end to a closing head block and at a second end to a piston tail, a magnetostrictive waveguide tube extending into a boring in at least one piston tail, a permanent magnet disposed on the at least one piston tail and a magnetostrictive waveguide tube comprising a conductive wire for receiving an interrogating pulse from a transducer, and wherein the interrogating pulse generates a helical return signal in response to a relative position of the permanent magnet in relation to the wave the guide tube, while the transducer is configured to receive the helical return signal and output a position of the closing head block corresponding to the at least one piston tail.

In another aspect, the present description applies to a method for determining a relative position of a closing head, which comprises that a magnetostrictive waveguide tube goes back and forth in engagement with a bore in a piston tail, a part of the waveguide tube is magnetized in the longitudinal direction with at least a permanent magnet attached to the piston tail, a conducting wire located inside the waveguide tube is pulsed to generate a toroidal magnetic field, and where a return signal is produced when the toroidal magnetic field impinges on the portion of the waveguide tube which is magnetized in the longitudinal direction, whereby the relative position of the closure head is determined from the return signal.

In another aspect, the present disclosure relates to a method of adding instrumentation to a closing head type blowout preventer, comprising removing a cylinder head jacket, removing a piston tail from a hydraulic closing head piston, installing a replacement piston tail, the replacement piston tail having a bore, installing a replacement cylinder head jacket, the replacement cylinder head has an instrumentation port, a magnet assembly is attached to the piston tail, and a magnetostrictive sensor is provided from the replacement cylinder head jacket so that the magnetostrictive sensor is configured to engage and disengage with the piston tail bore as the hydraulic closing head piston reciprocates.

Other aspects and advantages of the invention will be apparent from the following description and the appended patent claims.

There are attached drawings, on which:

Fig.1 is a sketch of a previously known blowout fuse with a closing head, shown partially cut through,

fig.2 is a sketch of the cover unit for a blowout fuse with a closing head in accordance with the embodiments described here, shown in section,

fig.3 is a sketch showing details of a part of the cover unit for the blowout fuse with closing head shown in fig.2, and

fig.4 is a curve diagram showing cylinder pressure as a function of closing head gap in accordance with embodiments indicated in the present description.

In one aspect, embodiments described here apply to a blowout fuse with a closing head that includes instrumentation for determining the position of the closing head inside the blowout fuse. In another aspect, embodiments are described here that apply to methods for determining the closing head's position, speed or closing rate in a blowout fuse with a closing head.

Fig.1 shows a blowout fuse 10 of the closing head type. A well pipe 12 which may be part of a drill string located at the top of a well being drilled or part of a production string for a well undergoing oil or gas production is shown passing through a central vertical bore 14 in the main body 16 of the blowout protection 10. The main part 16 may have opposing horizontal passages 18 across the bore 14. The horizontal passages may extend outwards into covers 17 connected to the main part 16. In the passages 18, closing heads 20 operated by hydraulic pistons 22 operate in their respective cylinder liners 23 located in respective hydraulic cylinders 19 connected outside the valve covers 17. The pistons 22 can drive the closing heads 20 back and forth in the passages 18 and thereby open and close sealing pieces or wear trays 24 in the sides of the closing heads 20 in relation to the surface of the pipe 12. Hydraulic fluid connections ( not shown) works in conjunction with opening a chamber 25 and closing a chamber 26 for positioning of the closing heads 20.

As shown, the blowout fuse 10 with a closing head can have a tail part 28 connected to the piston 22. The tail 28 of the piston 22 goes back and forth inside a cylinder head 30 which can be bolted to or otherwise connected to the cylinder 19.

It is desirable to know or locate the position of the closing heads 20, as described above. This can be done by locating components for a magnetostrictive sensor inside the hydraulic cylinder head casing which is connected to the cylinder 19 shown in fig.1. Those skilled in the art will understand that the embodiments described herein can be broadly applied to any shut-off type blowout preventer, and even more broadly to any device that has shut-off heads.

Fig.2 and 3 show a cylinder head and sensor arrangement according to the embodiments described here. The cylinder head 30 can be connected to the cylinder 19 via screwed, welded, flanged or any other connections known in the field. The piston 22 shown in its fully open position may be connected to the piston tail 28, which has a piston tail bore 32 extending at least partially through the piston tail 28. A magnet assembly 38 may be concentric with and connected to the piston tail 28 by of screws 40, which in some embodiments are non-magnetic screws. A spacer 42, such as an O-ring, may be located between the magnet assembly 38 and the piston tail 28.

The magnet assembly 38 may comprise two or more permanent magnets. In certain embodiments, the magnet assembly 38 may include three magnets, four magnets in other embodiments, and even more than four magnets in still other embodiments.

A stationary waveguide tube 44 can be located inside the cylinder head 30 and can at least partially extend into the piston tail bore 32 in the piston tail 28. Preferably, the piston tail 28 is located radially at a distance from the waveguide tube 44 so as not to interfere with the movement of the piston 22 or cause wear on the waveguide tube 44.

Likewise, the magnet assembly 38 can be located radially at a distance from the waveguide tube 44. In selected embodiments, magnets in the magnet assembly 38 can be located in a plane across the waveguide tube 44.

In addition, a conductive element or wire (not shown) can be placed through the center of the waveguide tube 44. Both the wire and the waveguide tube 44 can be connected to a transducer 46 located outside the cylinder head 30, through a communication port 48. The transducer 46 can also have suitable equipment for applying an interrogative electric current pulse to the conducting wire.

O-rings 50 placed between the cylinder head 30 and the hydraulic cylinder 19 can seal against leaks. O-rings can also be used to seal the connection between the communication port 48 and the transducer 46.

As the closing head 20 moves axially, the piston tail 28 and the magnet assembly 38 move axially to the same extent. By driving the magnetostrictive sensor arranged therein, it thus becomes possible to determine the position of the closing head 20 on a continuous basis.

With regard to the operation of the magnetostrictive sensor, magnetostriction refers to the ability of certain metals, such as iron or nickel or nickel-based alloys, to expand and contract when placed in a magnetic field. A magnetostrictive waveguide tube 44 may have an area within an external magnet assembly 38 which becomes magnetized in the longitudinal direction as the magnet assembly 38 moves longitudinally around the waveguide tube 44. As described above, the magnet assembly 38 comprises permanent magnets which can be placed in positions at equal distances from each other in a plane across the waveguide tube 44 and radially equidistant relative to the surface of the waveguide tube 44. An external magnetic field is created by the magnet assembly 38, which can magnetize a region of the waveguide tube 44 in the longitudinal direction.

The waveguide tube 44 surrounds a conducting wire (not shown) arranged along its axis. The conductive wire may be periodically pulsed or interrogated with an electric current in a manner well known in the art, such as by the transducer 46 placed on the outside of the jacket 30. Such a current pulse produces a toroidal magnetic field around the conductive wire and the waveguide tube 44. When the toroidal magnetic field intersects the magnetic field generated by the magnet assembly 38, a helical or helical magnetic field is induced in the waveguide tube 44 to produce a sound pulse which travels towards both ends of the waveguide tube 44. Suitable attenuators (not shown) at the ends of the waveguide tube 44 can prevent the rebound of echo of the pulse from performing. At the transducer or head, however, the helical wave is transformed into a waveguide twist which exerts a lateral mechanical stress on very thin magnetostrictive bands connected to the waveguide tube 44. A phenomenon known as the Villari effect causes flux links from magnets, running through sensing coils, to become distributed by the traveling mechanical tension waves in the bands and thereby develop an electrical tension across the coils.

The transducer 46 can also amplify this voltage for measurement or control purposes.

Because the current pulse travels at close to the speed of light, while the acoustic wave pulse travels roughly at only the speed of sound, there exists a time interval between the moment the transducer at the head end receives each pulse compared to the timing of the electrical pulse produced by the electronics at the head end. This time interval is a function of the distance that the external magnet assembly 38 is located from the transducer of the tube. By carefully measuring the time interval and dividing by the tube propagation speed, the absolute distance of the magnet assembly from the head end of the tube can be determined.

In the event of loss of signal, there is no loss of information and no resetting to zero or to the starting point of any reading is required. The reading is absolutely determined by the location of the magnet assembly 38 relative to the transducer 46.

With knowledge of the closing head's absolute position, it can be determined whether the closing head is completely closed, whether the closing head has hung up, to what extent the sealing piece or wear pad on the front of the closing head is worn, and to what extent there is a backlash or wear in the piston mechanism. Based on successive interrogating pulses, it is also possible to measure the closing speed of the piston and its rate of movement or acceleration and deceleration.

As used herein, the term "closing head gap" denotes the translational gap between horizontally opposed closing heads in the blowout fuse. In selected embodiments, the closing head gap can be calculated and registered by determining each closing head's absolute position and thereby making it possible to calculate the relative distance between the closing heads. In selected embodiments, the position of the closure heads in the blowout fuse can be determined using a cylinder and sensor arrangement, similar to that shown in Figs. 2 and 3, or using any other instrumentation mechanism known in the art. Furthermore, the relative position of the closing head can be sent to a data capture device and used to calculate and regulate the closing head gap in the blowout fuse. In selected embodiments, the closure head gap can be quantified by a clearance distance (eg, inches, centimeters, etc.) between two closure heads, either measured or calculated.

As used herein, the term "cylinder pressure" refers to the amount of hydraulic pressure exerted on pistons configured to close the shutoff heads in a blowout preventer. As such, cylinder pressure values can be measured in different positions (ie at different closing head gaps) and recorded. As such, a blowout preventer according to embodiments described herein may include a pressure transducer or any other device configured to sense cylinder pressure. Furthermore, a pressure-sensing device can send a signal to a data capture device to record the cylinder pressure in selected positions.

Alternatively, a force transducer can be used to report and record the actual closing head force, the closing head force being a function of cylinder pressure. For the purpose of this description, cylinder pressure and closing head force can be used interchangeably, after which closing head force can be defined as cylinder pressure multiplied by the cross-sectional area of the closing head pistons.

Reference is now made to fig. 4 where a curve diagram shows cylinder pressure as a function of closing head gap in accordance with embodiments of the present description. The data shown in fig.4 were observed during cutting of different shapes and sizes of cables and pipe shapes with closing heads in a blowout fuse. This data can be measured and recorded using any of the devices and methods previously described. The curve diagram contains data points and curves that facilitate the understanding of the circumstances surrounding the closure of closure heads around an object.

The curves consist of data points observed while various cables and pipe shapes are cut with closure heads in a blowout fuse. The curve 100 illustrates data observed while a part being cut is cut with new "closure head blocks", a closure head block being a component attached to a closure head configured to cut an object extending through the blowout fuse. Likewise, curve 200 shows data observed while a cutting part is cut with well-tested closing head blocks. Curve 300 represents data observed while cutting a 5.5 inch thick wall, while curve 500 shows data while cutting a 3.5 inch pipe and cable with a blowout preventer. Finally, curve 600 shows data observed while only one cable is cut with the blowout fuse.

In addition, the curve diagram reflects data points that may indicate that certain events are taking place while the closure heads in a blowout preventer are closing around an object. In particular, the data points 401 indicate positions where the cylinder pressure begins to overwrite the operator closing pressure after coming into contact with the object. Also, as shown, the data points 402 in the curve diagram may indicate the cylinder pressure required to cut pipes and/or cables running through the blowout preventer. Furthermore, the data points 402 can indicate the location of the closing heads when pipes and/or cables are cut. As used herein, "cutting pressure" is the amount of cylinder pressure required to begin cutting a pipe and/or cable. The data points 403 may indicate where the closure heads come into contact with flexible elements, such as gaskets. The data points 404 can indicate the position and cylinder pressure when the closing heads make contact with each other. The data points 405 may indicate increasing cylinder pressure from contact between the closing heads and gaskets, thereby implying that the closing heads are completely closed.

In one embodiment, a blowout fuse can have a cylinder, closing head and sensor arrangement similar to that shown in Fig. 2 and 3. The blowout fuse can be tested cyclically by opening and closing the closing heads several times. A cycle can contain complete opening and closing of the closing heads once. Cyclic testing is a method known in the art that can be used to evaluate the reliability of the components being tested. While a blowout fuse is being cyclically tested, data comprising cylinder pressure at selected positions (ie closing head gap) can be measured and recorded for each cycle. This data can then be compiled to show how components of the blowout preventer (eg gaskets, seals, wear plates and locking mechanisms) react or move during the cycle. Such data can be useful in determining when components need to be replaced or modified. Reasons for replacing blowout preventer components may include, but are not limited to, excess play and wear.

Other wellhead components within this industry can be affected by movement over time. The wellhead components can e.g. include a wellhead coupling, failsafe valves, control box wedges, diverter lock segments, stack mounted accumulator bottles and possibly other components known in the art. In one embodiment, a sensor arrangement comprising a magnetostrictive sensor may be used to determine the position of at least one wellhead component. The magnetostrictive sensor can send a signal to a data capture device which can then record the position of at least one wellhead component. The magnetostrictive sensor can send several signals to the data capture device over a selected time interval to thereby indicate possible movement of the wellhead component in the selected time interval.

It is also desirable to add instrumentation to existing blowout fuses with a closing head. To add instrumentation to existing closed-head blowout preventers, it may be possible to simply replace or modify a portion of the closed-head blowout preventer, reducing the cost required to upgrade existing equipment to include instrumentation. It can e.g. be possible to add instrumentation to existing closed head blowout preventers by replacing or modifying only the cylinder head cover and piston tail.

The existing cylinder head cover and piston tail can be removed. The removed piston tail can be modified to have a central bore for instrumentation and then reattached to the hydraulic piston, or a new piston tail having a central bore can be attached to the hydraulic piston. Likewise, the cylinder head cover can be modified to include an instrumentation port, or a new cylinder head cover that has an instrumentation port can be attached to the main body of the blowout fuse with a closing head. A magnet assembly can be attached to a piston tail which has a central bore and a magnetostrictive sensor can, as described above, be at least partially arranged in the central bore of the piston tail.

After the addition of the instrumentation, it may be necessary to calibrate the magnetostrictive sensor in relation to the fully open and fully closed position of the closing head. In addition, instrumentation for determining the position of the closing head can be operatively connected to a digital control system. The digital control system can then be used to monitor, display and/or control the position of the closing head on the basis of an electronic signal from the magnetostrictive sensor.

Embodiments described herein can advantageously provide instrumentation for closure head blowout fuses that are easy to install and that accurately measure the position, velocity and acceleration of a closure head. In addition, the designs described here do not intervene in the cylindrical cylinder's cavity, which can provide additional advantages.

The designs described here can also open up flexibility with regard to the components of blowout fuses with a closing head, while at the same time ensuring a precise construction of the blowout fuses with a closing head. As an example, customers may want blowout fuses with a closing head that is equipped with, or that is without instrumentation. The integrity of the rod connecting the closure head to the piston is not compromised by the presence of an internal bore for the placement of a sensor after the sensor is arranged in the rod, and thus no reinforcement or modification of the rod is required for use with or without instrumentation. In addition, cylinder heads and tails that provide instrumentation can easily be exchanged for cylinder heads and tails that do not provide instrumentation ports. In this way, parts can be interchanged and existing blowout fuses with a closing head can be easily modified to include instrumentation, while customers will have flexibility with regard to product selection without the risk of incompatible fabrication.

Designs described here can advantageously provide methods for testing and monitoring components in blowout fuses in order to detect and/or prevent potential problems or questions during their operation. Designs described here can e.g. provide a method for sensing slack in a locking head's locking mechanism.

Furthermore, embodiments described here can provide a method of testing and measuring the life cycle and/or maintenance intervals for certain components (e.g. seals, gaskets, locking mechanisms) found in blowout fuses. Furthermore, designs described here can provide a method for detecting wear and/or interference issues before and during the operation of a blowout fuse.

In addition, embodiments described herein may advantageously provide a method and device for recording the locking position over time to graphically create an estimated remaining life for rubber components. Further, embodiments described herein may provide means and methods for monitoring the position of components in blowout preventers during seal development and testing to determine how elastomeric seals perform and react, so that the elastomeric designs can be improved. Furthermore, embodiments described here can provide methods and devices for determining when pipes have been cut by a blowout fuse with a closing head and thereby affect pressure accumulator requirements.

Embodiments described here can also be applied to the movement of pistons in an annular blowout fuse. Such embodiments may include the use of position indicators to determine replacement intervals for wear plates and packing assemblies in annular blowout fuses. Furthermore, embodiments described herein may be applied to stack components, including, but not limited to, wellbore connections, failsafe valves, control box wedges, diverter lock segments, and pressure accumulator bottles.

Although the invention has been described with respect to a limited number of embodiments, those skilled in the field who benefit from this description will understand that other embodiments may be found, which do not leave the scope of the invention described here. Accordingly, the scope of the invention shall be limited only by the appended patent claims.

Claims (7)

PATENT CLAIMS 1. Procedure for monitoring a cylinder pressure exerted on closing heads in a blowout fuse, the procedure comprising that: – a relative position of the closing heads in the blowout fuse is sensed with a magnetostrictive sensor, –signals are sent from the magnetostrictive sensor to a data capture device, -a cylinder pressure exerted on the closing heads is sensed with a pressure-sensing device, -signals are sent from the pressure-sensing device to the data capture device, and - the sensed cylinder pressure is recorded as a function of the sensed relative position with the data capture device. 2. Method as stated in claim 1, and which includes that the sensed cylinder pressure is displayed graphically in relation to the position of the closing heads with the data capture device. 3. Procedure as specified in claim 1, which further includes that: – data recorded by the data capture device is assessed, and - it is decided that the closing heads are closed when the cylinder pressure reaches a certain value. 4. A method as set forth in claim 3, wherein the closed position comprises a closing head gap of approximately zero inches. 5. Method as stated in claim 1, and which further includes that a remaining life expectancy for sealing elements in the closing heads in the blowout protection is determined from the cylinder pressure recorded as a function of the closing heads' relative position. 6. Method as specified in claim 1, and which further comprises that it is determined from the cylinder pressure recorded as a function of the relative position of the closing heads when a pipe located between the closing heads is cut. 7. Procedure as specified in claim 1, which further includes that based on the cylinder pressure recorded as a function of the relative position of the closing heads over a selected period of time, a maintenance interval for components in the blowout protection is determined.