US 3777813 A
This invention concerns a system using a hydraulic control line to control a downhole safety valve located in a string of tubing suspended in a well bore drilled in the earth. The hydraulic control line is in the space between the tubing string and the casing of the well bore. A special lever actuated valve means is used in the wall of the tubing string at the point where the hydraulic line connects into the tubing string downhole. The insertion of a wireline retrievable safety valve holds the lever actuated valve open. When the safety valve is removed the force of the tubing pressure causes the lever actuated valve to close.
Description (OCR text may contain errors)
United States Patent 1191 1111 3,777,813
Dendy et al. Dec. 11, 1973 CHECK VALVE FOR HYDRAULIC 2,780,290 2/1957 Natho [66/72 CONTROL SYSTEM 4/1945 Laird et al. 166/224 s  Inventors: Jackie D. Dendy; Robert D.
Johnson, both of Lafayette; Robert M. Peevey, New Orleans, all of La.
2/1963 Tausch 7/1940 Toney Amoco Production Company, Tulsa,
[1.8. CI. 166/72, 166/224 S Int. Cl E2lb 33/03, E2lb 43/12 Field of Search 166/72, 724 S 2: 2:37); 'li fii ikjkiiiiinu."2225 Primary Examiner-James A. Leppink Attorney-Paul F. l-lawley et al.
571- ABSTRACT This invention concerns a system using a hydraulic control line to control a downhole safety valve located in a string of tubing suspended in a well bore drilled in the earth. The hydraulic control line is in the space between the tubing string and the casing of the well bore. A special lever actuated valve means is used in the wall of, the tubing string at the point where the hydraulic line connects into the tubing string downhole. The insertion of a wireline retrievable safety valve holds the lever actuated valve open. When the safety valve is removed the force of the tubing pressure causes the lever actuated valve to close.
4 Claims, 2 Drawing Figures PAIENIEnMc 11 um 3.777.813
CHECK VALVE FOR HYDRAULIC CONTROL SYSTEM BACKGROUNDOF THE INVENTION 1. Field of the Invention Thisinvention relates to downhole safety valves, especially those used in strings of tubing used to produce oil and gas from underground deposits. 4
2. Setting of. the Invention Commercial quantities of oil andgas are found deep within the earth. These deposits are recovered by drilling a well bore to the deposit. The well bore is lined with a steel casing with cement betweenthe casing and the borehole wall. A string of tubing, which is really small diameter pipe, e.g., 2% inches, is suspended inside the casing from the surface to the deposit. A packer seals the annular space between the exterior of the string of tubing and'the casing at a level just above the location ofthe deposit of oil=and gas. The oil and gas are produced through perforations in the casing up through the tubing string to the surface.
If the deposit of oiland gas is found in water covered areas, such: as the Gulf of Mexico, special subsurface safety valves are required tobe set inthe tubing string at a position below the mudline. The reason for this is if the wellhead equipment or casing'above the ocean floor is damaged or broken, the subsurface safety valve will close and prevent any escape of oil-.or gas. One particularly popular type subsurface safety valve is the type which is held open by a separate hydraulic fluid from a hydraulic control-line. This hydraulic flow line normally extends from the surface to the downhole safety valve and is positioned in the annulus between the string of tubing and the casing. In many of the older wells, the casing cannot withstand as high a pressure as can the smaller tubing string. Allowing tubing pressure to the tubing-casing annulus in high pressure wells is dangerous even on new wells; thus, common practice is to prevent this occurrence on. such high pressure wells. That is one reason why high pressure production is through the tubing string.
We have discovered that under certain conditions there is a potential hazard to the well casing. This can occur if the hydraulic control line is broken or develops a leak at a time when the safety valve is not in position. Then the higher pressure fluid in the tubing can escape through the hole in the control line thus raising the pressure in the annulus. If the pressure is sufficiently high it can cause failure of the casing. Our invention discloses a system to eliminate this potential hazard.
BRIEF DESCRIPTION OF THE INVENTION This invention concerns a system using a hydraulic control line to control a downhole safety valve located in a string of tubing suspended in a well bore drilled in the earth. The hydraulic control line is in the space between the tubing string and the casing of the well bore. The lower end of the hydraulic control line leads to a tubing port in a special section of the tubing string. There are seals on the safety valve'so that when it is inserted, the tubing port is sealed from the remainder of the string of tubing, but is in fluid communication with the hydraulic piston of the safety valve. A special lever actuated valve means is used in the wall of the tubing string at the point of the tubing port operable to close the tubing port. The insertion of a wireline retrievable safety valve holds the lever actuated valve open and removal of the safety valve permits the lever actuated valve to close.
BRIEF DESCRIPTION OF THE DRAWINGS Various objects and a better understanding of the invention can be had from the following description taken in conjunction with the drawings in which:
FIG. 1 is a donwhole view partly in section showing a subsurface safety valve and hydraulic control line system featuring our invention.
FIG. 2 illustrates an enlarged view showing the lever actuated valve of FIG. 1 for shutting off the interior of the tubing from the hydraulic control line.
DETAILED DESCRIPTION OF THE INVENTION Attention is first directed to FIG. 1 which illustrates a casing 10 suspended in a well bore 12. The section of FIG. 1 is typically located in a well drilled in a watercovered area and is located at a level below the mudline. Suspended within casing 10 is a string of tubing 14 which extends upwardly to the surface to conventional wellhead equipment not shown. The lower end of tubing 14 extends downwardly to the producing interval in a conventional manner. A wireline retrievable safety valve 16 is suspended in tubing string 14. A typical and suitable safety valve 16 is commercially available from Otis Engineering Corporation, Dallas, Texas, and is de' scribed in their l96667 catalog, page 384] as an Otis Wireline Removable Ball-Type Safety Valve." A special section 1 8, which is sometimes referred to as a landing nipple, is provided in tubing string 14. An external hydraulic control line 20 is provided in annulus 22 between casing 10and tubing 14. This hydraulic control line extends to the surface or other point where hydraulic fluid under pressure can be obtained.
Hydraulic control line 20 is connected into cavity 24 in landing nipple 18. Cavity 24 is isolated from the interior of tubing 14 upon insertion of safety valve 16 by upper seals 26 and lower seals 28 which are on the exterior walls of safety valve 16. Safety valve 16 also includes locking means 30 and wireline latching neck 32. In its normal operation hydraulic fluid is supplied through hydraulic control line 20 into cavity 24 and into a port 34 which will actually hold the valve section 36 in an open position. The internal means of the safety valve 16 will not be shown as they are well known and the details of these are not a part of this invention. It is sufficient to say that if hydraulic pressure is relieved or reduced on line 20 either by intentional means or by breakage of the line, the valve closes and no fluid can flow upwardly through tubing 14. This prevents pollution in event of a severe storm or ship or other catastrophe breaking the wellhead equipment.
The entire valve 16 must be retrieved periodically for checking or for replacement. As mentioned above in the setting of the invention, when wireline retrievable safety valve is pulled or removed, and if hydraulic line 20 is broken, if it were not for our invention, then the high pressure of the fluid in the tubing string would be exerted against the casing. This presents a grave and dangerous situation because there is a distinct possibility that the casing may-be ruptured. We eliminate this problem by our invention. We provide a lever actuated check valve 38. This can be seen more clearly seen in FIG. 2. Shown in FIG. 2 is valve seat 40 which is formed in the wall of the landing nipple at the inlet of hydraulic line 20. This is arranged to receive ball valve 42 of valve means 38. This valve means includes a pivot 44 about which the valve means rotate. Valve means 38 includes a lever 46 and valve support arm 48. Members 46 and 48 are rigidly fixed together and preferably are made an integral part which pivots about pivotal point 44. A spring 50 is provided and biases the valve 42 in .a direction indicated by arrow 52 toward seat 40. When the retrievable valve means 16 is inserted into landing nipple 18 it strikes lever 46 and shoves it into the position shown in FIG. 2. This causes valve 42 to be held in an open position away from seat 40. Then while the safety valve is in the position shown in FIG. 1, hydraulic fluid from control line 20 is effective to operate safety valve 16. However, when valve 16 is removed, springs 50 causes valve 42 to seat in seat 40. Force exerted by the tubing pressure also aids in closing the valve. Thus, fluid in the tubing'string 14 cannot flow into control conduit 20. Thus, even though line 20 may be damaged and contain a leak, the high pressure fluid in tubing 14 cannot enter annulus 22 and therefore will not apply the high pressure to casing 10.
While the above description has been made in considerable detail, various modifications can be made thereto without departing from the spirit or scope of the invention.
1. In a system in which a retrievable safety valve is set in a tubing string in a well bore and is controlled by hydraulic control line extending from a source of controlled hydraulic fluid to a port in the tubing string adjacent the safety valve, the improvement which comprises:
a cavity in the wall of said tubing string; i
said port opening into said cavity;
a seat in said port in said cavity;
a valve for said seat;
first means biasing said valve toward said seat;
second means extending into the interior of said tubing string operable to hold said valve away from said seat when said safety. valve contacts said second means upon insertion of said safety valve in said tubing string adjacent said cavity.
2. in a system in which a retrievable safety valve is set in a tubing section in a tubing string in a well bore and controlled by hydraulic control line extending from a source of controlled hydraulic fluid to a port in said tubing section adjacent said safety valve, the improved tubing section comprising:
a cavity in said tubing section;
a seat in said cavity at the opening of said port;
a pivot in said cavity;
a pivoting unit pivotally mounted on said pivot and including (a) an arm which supports said valve at its outer end and (b) a lever, the pivot being between said arm and said lever, said lever extending out of said cavity into the passage of said tubing section when said valve is seated in said seat.
3. The device as defined in claim 2 including means urging said valve toward said valve seat.
4. A device as defined in claim 3 in which said means is a spring.