VENT LINE SYSTEM

Abstract: A vent line system (10) which is adapted for connection to a flow diverter (12) attached to a drilling rig. The system assures that the vent line is always open for discharge of pressure drilling fluid away from the drilling rig in one of two directions.

Description: VENT LINE SYSTEM The invention disclosed herein relates to a di¬ verter apparatus and system for redirecting the flow of drilling fluid or mud and cuttings that would otherwise be blown upward to the rig floor during a "kick" encountered 5 during initial hole drilling. In general, the apparatus and system according- o the invention may be used beneath the drilling floor of any land or marine drilling rig, but in particular the invention finds application with floating drilling equipment. More particularly, the invention re- 0 lates to a vent line system for connecting to a diverter in which the system has a blast deflecting means to deflect the mud and cuttings flowing in the vent line overboard as¬ suring that no means are provided to prevent such flow. When drilling an oil or gas well from a floating 5 vessel, an initial large diameter bore hole is established to shallow depths. Protective conduit typically thirty (30) inches (76.2 cm) in diameter, is secured in the shal¬ low bore through which the drilling takes place. Then a subsea riser is put in place extending from the sea floor D to the drilling rig platform. Flow diverters are typically provided below the rig floor and between the riser and the rotary table of the drilling rig for the purpose of safely venting unbalanced well bore pressure which may produce an upward flow of well O PI - 2 - flow fluid in the riser having sufficient impetus to issue from the top of the riser, thereby contributing a hazard to personnel and equipment. Such an occurrence, called a "kick" results when the formation fluid pressure exceeds the head in the riser and borehole and is sometimes en- countered in conductor hole drilling, making a flow diverter essential before blowout preventers are connected to the drilling system. A flow diverter is considered necessary for safe operation on a floating offshore drilling rig where blowout preventers are placed on the sea floor only after the casing has been set to a considerable depth be¬ low the sea floor. Flow diverter systems which have been provided in the past have faced significant safety problems because the available equipment has required that valves external to the diverter be placed in the vent line system. Such valves have been necessary because the vent line was in general open to the annulus of the drilling conduit below the di¬ verter element adapted for closing the vertical flow path of the bore. The vent line valve was opened simultaneously with or prior to the closing of the diverter element. Typically a "T" joint has been provided to direct flow in the vent line to one of two discharge lines, one leading to the port side of the vessel, the other to the starboard. Valves in each of the discharge lines enabled rig personnel to close one of the discharge lines so that vent line flow could be discharged to the leeward side of the- vessel. In the past, such external valves have sometimes been locked closed by rig personnel while testing the flow diverter system, but after the diverter had been made op¬ erational during drilling, the external valves have been unintentionally left locked closed. On other occasions, control system elements for remotely operating the external valves have been inadvertently incorrectly connected, re- suiting in simultaneous closure of all of the external di- OMPI WIPO verter system valves and the diverter itself. If such flow diverters have closed about the annulus of a. drill pipe or other object in the well bore, such flow diverter systems have created an extremely dangerous situation, and in fact, in some cases they have exploded with the result of loss of life and property. The complexity of the circuitry that sequences the operation of the valves and the diverter in¬ vites mistakes in connection even by skilled technicians. The object of the invention described below, to provide a vent line system which, when used in combination with a novel flow diverter which requires no external vent line valves, is failsafe; that is, when a kick occurs dur¬ ing shallow hole drilling of a well before a blowout pre¬ venter has been provided, that kick cannot be accidently confined by the vent line system to build pressure and ex¬ plode' even if controls are isconnected or malfunctioning. Accordingly, the present invention provides a vent line system adapted for use with a flow diverter system comprising, a vent line adapted for connection to a flow diverter, a first deflect line having an opening at its first end to the atmosphere, a second deflect line having an opening at its first end to the atmosphere, and deflecting means attached to the vent line and to the re¬ spective second ends of the. first and second deflect lines for assuring that communication from the ventline to the at¬ mosphere is via either the first or second deflect lines and for assuring that said first and second deflect lines cannot be closed simultaneously. According to the invention three embodiments of the deflecting means are described. The first includes a deflecting element which may be angularly rotated in the body of the deflecting unit to direct the flow to one or the other of the outlet ports. According to the second embodi¬ ment, a deflecting element is adapted to move in a linear direction between two positions intermediate the inlet and O PI - A - outlet ports and accomplishes the same function as the first embodiment. A third embodiment of the deflecting unit is a rotary sleeve blast, deflector/selector in which the axis of the sleeve is parallel to the inlet flow and a removable target is provided for impingement of abrasive well flow. The vent line system of the invention requires but a single motion to operate, is simple and relatively in¬ expensive to manufacture. Further features and advantages of the invention will become more apparent by reference to the drawings which are apprehendedhereto and wherein like numerals indi¬ cate like parts and wherein an illustrative embodiment of the invention is shown, of which: Figure 1 illustrates the vent line system accord- ing to the invention attached to a diverter; Figure 2 shows an alternative embodiment of the blast deflector; Figures 3 and 3B illustrate another alterna¬ tive embodiment of the blast deflector; and - Figure 4 illustrates a flow diverter requiring no external valves to open the bore annulus to the vent line system. Figure 1 illustrates the vent line system shown generally at 10 in which a vent line 11 is connected to a flow diverter 12. As will be described below, diverter 12 is preferably connected below a drilling rig floor above a drilling conduit and is provided with means for connecting the vent line 11 for directing drilling rig mud and cut¬ tings away from the rig floor on the occasion of a kick. Attached to the diverter also is a flow line means 13 which is connected to the drilling rig mud system. The blast deflecting unit 14 of the system 10 is a "T" shaped connecting element having an inlet port 15 and outlet ports 16 and 17. Outlet ports 16 and 17 are connected to deflect lines 18 and 19 for directing the flow , _ OMPI from the diverter 11 in two directions. Typically one of the deflect lines is. directed to the port side of the vessel, while the other, deflect line is. directed to the starboard side. A blast deflector element 20 disposed within the body of the deflecting unit 14 is adapted to be placed in two positions. As illustrated in Figure 1 the deflector element 20 is disposed in a cylindrical or al¬ ternatively a spherically shaped body and is adapted to be placed in one of two directions for deflecting the flow from inlet port 15 to one or the other of the deflecting lines 18 or 19. Figure 2 shows an alternative embodiment of the deflecting unit 14' in which a blast deflector element 20' is adapted to move linearly along the body 14 ' to opposite positions whereby flow from the inlet port 15 is deflected to deflect lines 18 or 19. Figures 3A and 3B illustrate another alternative ambodiment of the deflecting unit 14" in which the axis of the deflecting element, in this embodiment a rotary sleeve 30, is provided parallel to the inlet port 15. A target 20", preferably one that may be easily replaced by opening target housing 31, provides a sacrificial erosive surface for impingement of abrasive solids in the well flow enter¬ ing inlet port 15. As illustrated in Figure 3A, the rotary sleeve 30 is in position to direct flow from inlet port 15 to outlet port 18. After rotary sleeve is rotated counter¬ clockwise by ninety degrees, inlet port 15 is opened to outlet port 19. An actuator 35 is provided to rotate sleeve 30. As illustrated in Figure 3B, the rotary actuator may be a motor 35 and gear 35' arrangement coupled to sleeve 30, but may be any motive and coupling means commonly em¬ ployed in oilfield applications for actuating valve elements. Seals 36, 37 are provided in body 14" for sealing against rotary sleeve 30. A seal 40 is provided to seal target ma- _O FI W IPO terial 20" against the body 14". A slot 38 in sleeve 30 and a stop 39 insures that sleeve 30 may travel only between the position shown in Figures 3 and one which is ninety degrees counterclockwise from that illustrated. In all of the embodiments of the invention, the deflector element 20, 20' or 20" is constructed from a material suited to be highly resistant to erosion from abrasive fluid flow. Such material may be carbide coated steel, steel with a tungsten coating, steel having a ceramic coating on the blast surface, or any suitable material. As illustrated in Figures 1, 2 and 3, the de¬ flector element and vent line system according to the in¬ vention provide a simple device which requires but a single motion to operate between one of two states, yet the vent line system is always open to the diverter thereby as¬ suring that the vent line system itself is prohibited fro - eing closed and thereby insuring that pressurized gas from the drilling conduit to which the diverter ±2 is connected is diverted away from the drilling vessel. Even if the de- fleeting element 20 is unintentionally left in a position causing the vent line fluid and mud to be directed to the -yindward side of the vessel, all that is required to direct the flow to the leeward side is to change the position of the deflecting unit 20 or 20' or 20". The diverter 12 is preferably of the type requiring .no external valves in the vent line 15. Such a diverter is presented by way of example in Figure 4. Figure 4 illustrates an embodiment of the flow di¬ verter 12 in which a piston 500 is provided not only for closing the annular packing element 52 about an object in the bore of the diverter, but also for closing a flow line 13 and opening a vent line 11 during an emergency. The piston 500 has an upper conical bowl portion 502 adapted for engagement with a packing element 52 and forcing it radially inward as the piston 500 moves axially upward. A hole 510 V *ATI in the piston wall is normally in alignment with a hole 512 in the body 50 of the diverter 12. The second hole 513 in the body wall, provided in alignment with the vent line11, is covered by the piston 500 wall when the. diverter is in its normal state. When a source of high pressure hydraulic fluid is provided beneath the piston 500 via conduit 520, piston 500 is forced upward thereby opening vent line 11 via hole 513 providing fluid communication with the. bore of the diverter 12. As piston 500 moves up, hole 512 in the body wall becomes covered by the lower part 525 of pis¬ ton 500, and ultimately, hole 512 becomes completely covered by the lower part 525 of the piston. Means are provided for insuring that the packing element 52 does not close about a pipe or other object in the bore hole before hole 512 is covered and hole 513 is opened by providing a space 530 above the packing element through which the packing element is free to move axially upward without being forced radially inward as the up¬ per conical portion 502 of the piston 500 moves up. Thus, a- means is provided by which the vent line 11 is opened and the flow line 13 is closed from fluid communication with the bore of the flow diverter 12 before the annular packing element 52 is enabled to fully close about a pipe or other object in the bore hole or to completely close the vertical flow path of the diverter 22 in the absence of an object in the bore. There has been provided a vent line system for use with a flow diverter in which no valves external to the d- verter are provided, assuring that inadvertent errors in operation or inoperativeness of valves external to the di¬ verter do not create the opportunity for closing flow exits from the diverter after the annulus is closed. Various modifications, and alterations in the de¬ scribed structures will be apparent to those skilled in the art of the foregoing description which does not depart from the spirit of the invention. • O PI " WIPO

Claims: CLAIMS 1. A vent line system adapted for use with a flow diverter system comprising, a vent line adapted for connection to a flow diverter, a first deflect line having an opening at its first end to the atmosphere, a second de¬ flect line having an opening at its first end to the at¬ mosphere, and deflecting means attached to the vent line and to the respective second ends of the first and second de¬ flect lines for assuring that communication from the vent line to the atmosphere is via either the first or second deflect lines and for assuring that said first and second deflect lines cannot be closed simultaneously. 2. The vent line system of claim 1, wherein the deflecting means comprises, a housing having a central body and three external ports, the ports being open to the- ceπ>- - - tral body, one of the ports being connected to the vent line a second one of the ports being connected to the first de¬ flect line and a third one of the ports being connected to the second deflect line, and a blast deflector element, dis¬ posed in the body and adapted to move from a first position, where flow from the vent line is directed to a first de¬ flect line, to a second position where flow from the vent line is directed to a second deflect line. 3. The vent line system of claim 2, wherein the blast deflector element is mounted within the central body for angular rotation from the first position to the second position. 4. The vent line system of claim 2, wherein the blast deflector element is mounted within the central body for linear movement from the first position to the second position. 5. The vent line system of claim 2 wherein the blast deflecting element is a rotary sleeve having an axis parallel to a first housing port connected to the vent line and mounted within the central body for rotation between a first position in which a first outlet in the sleeve is aligned with a second port in the housing connected to a first deflect line and a second position in which a second outlet in the sleeve is aligned with the third port in the housing connected to a second deflect line. 6. A diverting system for directing drilling fluid away from a drilling rig in the event of a kick com¬ prising, a vent line, a flow diverter adapted in the event of a kick to open the annulus of the drilling conduit to the vent line, and deflecting means connected to the vent line for assuring that the drilling fluid in the vent line will always be directed in one of two directions away from the drilling rig. 7. The .system of claim 6, wherein the de¬ flecting means comprises first and second deflect lines, a tubular "T" connecting element, where the outlets of the connecting element are connected to 'first and second de¬ flect lines, and the inlet of the connecting element is connected to the outlet of the vent line, and a deflecting element means disposed in the connecting element for di¬ recting flow from the inlet of the connecting element to at least one of the outlets of the connecting element. 8. The system of claim 7, wherein the deflecting element means comprises an element disposed between the out¬ puts of the connecting element and adapted for angular ro¬ tation from a first position, where flow from the vent line via the inlet of the connecting element is directed by the element to a first connecting element outlet, to asecond position, where flow from the vent line is directed by the element to a second connecting element outlet. 9. The system of claim 7, wherein the de¬ flecting element means comprises an element disposed between the outputs of the connecting element and adapted for linear movement from a first position, where flow from the vent line via the inlet of the connecting element is directed by the element to a first connecting element outlet, to a sec¬ ond position, where flow from the vent line is directed by the element to a second connecting element outlet. 10. The system of claim 6, wherein the de¬ flecting means comprises, first and second deflect lines, a housing having three external ports, one of the ports being connected to the vent line, a second one of the ports being connected to the first deflect line, and a third one of the ports being connected to the second deflect line, and a rotary sleeve in the housing having its bore coaxially aligned with the port connected to the vent line and adapted for rotation between a first position where a first sleeve outlet is aligned with the housing port connected to the first deflect line and a second position where a second sleeve outlet is aligned'with the housing port con¬ nected to the second deflect line. 11. The system of claim 10, wherein the de¬ flecting means further comprises, a removable target means disposed at the opposite end from the port connected to the vent line, the target means being constructed of an erosion resistant material. 12. The system of claim 10, further comprising actuating means for rotating the rotary sleeve between the first and second positions. OMPI WHO

Inventors: ROCHE JOSEPH R, ROCHE, JOSEPH, R.
Applicants: HYDRIL CO, HYDRIL COMPANY
Application year: 1984
Main classification: E21B21
IPC codes: E21B21, E21B33, F16K11