Accumulator recharging valve

Accumulator recharging valve wherein a valve is opened to drain the accumulator, and then the accumulator is recharged through another valve, the valves being operated by pipe string pressure after blanking off the flow passage therethrough by a wireline tool, the valve operations being controlled by a barrel cam whereby the drain valve and recharging valve are alternately opened by pressure cycles in the pipe string.

BACKGROUND OF THE INVENTION 
Some downhole oil field tools include accumulators for holding gas under 
pressure, the gas pressure being used after the tool is run downhole to 
actuate one or more tool elements. When an accumulator is used as a part 
of a downhole oil field tool, it is often desirable to alter the charge 
pressure of the accumulator while the tool is downhole so that the tool 
will not have to be brought to the surface for the changing of the charge 
pressure of the accumulator. Bringing the tool to the surface for 
recharging of the accumulator at a different pressure would involve a 
so-called round trip, that is, pulling of the drill string or other pipe 
from the well, recharging the accumulator at the surface, and then 
rerunning the tool and drill string back into the well hole. This 
invention seeks to provide an accumulator recharge valve the use of which 
will permit recharging of the accumulator while the tool is downhole in 
the well. 
SUMMARY OF THE INVENTION 
The accumulator recharge valve according to the invention is a 
pressure-balanced sleeve valve device, spring biased to block 
communication between the pipe string bore and the accumulator. The 
recharging operation is performed using string internal pressure 
manipulation together with a wire line-run blanking sub. The sleeve valve 
functions to first bleed off the pressure in the accumulator, and then to 
recharge the accumulator to a desired pressure. The accumulator recharge 
valve of this invention is adaptable for use with the accumulator of any 
downhole tool. In this disclosure, the accumulator recharge valve is 
illustrated as an integral part of a pressure-controlled expandable blade 
stabilizer, which is operable by alterations of the internal pipe string 
pressure from the surface, but the recharge valve may be used with other 
types of tools having one or more accumulators. 
A principal object of the invention is to provide a recharging valve 
apparatus for use in recharging the accumulator of a well tool while the 
tool is downhole in the well. Another object of the invention is to 
provide such an apparatus which includes a pressure balanced sleeve valve. 
A further object of the invention is to provide such an apparatus which 
operates by alteration of internal pipe string pressure and through use of 
a wireline-run blanking sub. Another object of the invention is to provide 
such an apparatus wherein the precharged accumulator pressure is first 
bled off and then the accumulator is recharged to a usually different 
desired pressure. A still further object of the invention is to provide 
such an apparatus which is simple, easily operated, and dependable. 
Other objects and advantages of the invention will appear from the 
following detailed description of a preferred embodiment of apparatus 
according to the invention, reference being made to the accompanying 
drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
The recharged valve is of generally tubular construction, and is positioned 
in an elongated ball housing 10 disposed within an upper body 11. Near the 
lower end of ball housing 10 there is provided a ball valve 12 having a 
diametric flow port 13 therethrough. An upper seat ring 14 has lower 
spherically formed seat surface 15 around a groove in which is disposed a 
circular seal ring 16. Seat ring 14 has inner O-ring seal 17 and outer 
O-ring seal 18, as shown. A lower seat ring 19 is disposed below ball 
valve 12 and has upper spherically formed seat surface 20 in a groove 
around which there is disposed a circular seal 21. O-ring seal 22 and 
O-ring seal 23 seal around the exterior and the interior of seat ring 19. 
Seat rings 14, 19 are joined by two oppositely disposed bars 24, one being 
shown, which are each arcuately formed at their outer surfaces which are 
disposed against ball housing 10. The inner surfaces of bars 24 are along 
a cord of the interior curve of valve body 10. Seat ring 14 is disposed at 
its upper side against a unitary collar 25 formed at the interior of valve 
body 10, and the lower side of seat ring 19 is disposed against the upper 
end 26 of a tubular cam body 27, having O-ring seal 27a therearound, which 
is connected to the lower end of ball housing 10 at threaded connection 
28. Member 27 is interiorly recessed at 29 to provide a space for helical 
compression spring 30 therein, the lower end of spring 30 being engaged 
against shoulder 31 at the lower end of recess 29 and the upper end of 
spring 30 being disposed against a unitary collar 32 formed around a 
sleeve 33, the spherically formed upper end 34 of sleeve 33 engaging 
against the lower side of ball valve 12. Sleeve 33 is biased upwardly 
against ball valve 12 by the spring 30. Ball valve 12 has a flat 35 at 
each of opposite sides (one shown), and a short cylindrical bar 36 extends 
from the center of each flat 35. Each flat 35 includes a slot 37 curved at 
its inner end and open at its outer end at the outer curvature of the ball 
valve 12. Each bar 24 has a longitudinal slot 38 therein in which one of 
the cylindrical bars 36 is slidably disposed. Each bar 24 has a short 
cylindrical bar 39 protruding therefrom which is slidably engaged within 
one of the ball slots 37. When ball valve 12 is moved downwardly by 
downward movement of piston sleeve 43, caused by increased pressure within 
the tool passage, the ball 12 is caused to rotate by 90.degree. to isolate 
the flow passage 13, the rotation being caused by action of the two bars, 
or pins, 39 in the angular slots 37 as the bars 36 move straight down in 
slots 38. When the ball is returned upward, the ball rotates 90.degree. in 
the opposite direction to its original position shown in FIG. 1C with 
passage 13 open, as shown. 
There is a narrow annular clearance space between valve body 10 and upper 
body 11. A port 41 closeable by screwed in plug 42 at the enlarged 
interiorally threaded outer end of port 41 may be opened to inject oil or 
other liquid lubricant into the annular clearance space. The piston sleeve 
43 is outwardly thickened at its upper end 44 and an O-ring seal 45 is 
provided between the thickened upper end 44 of piston sleeve 43 and the 
interior of a sleeve 46. The lower end of sleeve 46 abuts the upper side 
of collar 25, previously mentioned. Sleeve 46 has port 46a therethrough. 
The lower end of piston sleeve 43 is spherically formed and is engaged 
against the upper side of ball valve 12. Sleeve 46 is spaced inwardly of 
valve body 10, leaving a clearance space 47 of annular shape. O-ring seal 
17 seals between the upper seat ring 14 and the lower end of piston sleeve 
43. The space between piston sleeve 43 and sleeve 46 provides an annular 
accumulator space 48 adapted to be filled with a gas under pressure before 
the lowering of the tool into the well. The ball valve assembly which has 
just been described and the tool parts therebelow were disclosed in 
application Ser. No. 368,996, filed Apr. 16, 1982, and the accumulator 
recharging valve which is the subject matter of this invention extends 
from collar 25 within ball valve housing 10 and an upper end cap ring 50. 
End cap 50 has O-ring seals 50a and 50b and wiper ring 50c therearound, 
and has therethrough a port 51 the upper end of which is enlarged and 
threaded to receive check valve 52 and threaded plug 53. The accumulator 
space 48 is initially charged with pressured gas at the surface, before 
the tool is run into the well, by removal of plug 53 and by injection of 
pressured gas, e.g. nitrogen gas, through check valve 52 and port 51, to a 
predetermined selected pressure. The gas injected through check valve 52 
and port 51 flows around the sleeves therebelow which are immediately 
within valve ball housing 10 to enter the accumulator space from its lower 
end. The lower end of sleeve 46 is notched to permit flow therepast. The 
upper barrel 54, middle barrel 55, the barrel of sleeve 46 of the 
recharging valve function together to serve as an outer body for the 
recharging valve. These barrels 54-55 and 46 have milled flats on their 
outer peripheries to provide fluid passage therepast within ball valve 
body 10, and upper barrel 54 and lower barrel 46 have milled end notches 
57, 58, respectively, to provide fluid communication from the check valve 
52 to the accumulator space 48. Camming pin holder 60, in the form of a 
sleeve, is screwed into the reduced diameter lower end of upper barrel 54 
at threaded connection 61. Inner sleeve 62 serves as the valving means for 
prohibiting or permitting communication between the drill string bore (the 
drill string being connected to the upper socket 63 of upper body 11) and 
the accumulator space 48. Sleeve 62 is provided with a polished bore in 
its lower end portion 62a, where the chevron seals of a wireline-run 
blanking sub (not shown) can seal against the bore. Locking grooves 64, 
65, 66 around the inner periphery of sleeve 62 at its vertical central 
section are configured to latch and hold a wireline blanking sub based on 
the general type of landing mandrel shown in the Otis Engineering 
Corporation catalog appearing in the Composite Catalog of Oil Field 
Equipment and Services, 1980-81, Volume 4, pp. 5972-5973. Use of a Type R 
or X Otis selective mandrel, with its lower end blanked off to prevent 
fluid flow, permits landing the mandrel selectively in a particular sleeve 
62, even through multiple tools with corresponding sleeves 62 having the 
same bore diameter but different locking groove patterns) are in the same 
string. 
The outer diameter of sleeve 62 is provided with a three position barrel 
cam slot 68. The layed out pattern of barrel cam groove 68 appears in FIG. 
3 of the drawings. The barrel cam groove 68 is engaged by camming pin 69 
carried by camming pin holder 60. 
Sleeve 62 has perforate spring ring 71 attached thereto by Spiralox 
retaining ring 72, in order to provide a reaction point on the sleeve for 
biasing the return spring 73. Before the blanking sub is landed inside 
sleeve 62 at grooves 64-66, the plural circularly spaced ports 75 in the 
upper end of the sleeve are isolated by O-ring 74 and wiper ring 76. 
Return spring 73 holds pressure balanced sleeve 62 upward. When the 
blanking sub is latched into grooves 64-66 of sleeve 62, application of 
pressure within the drill string above the blanking sub causes sleeve 62 
to move downwardly, following the long cam groove course 78 (see FIG. 3). 
When sleeve 62 is moved downwardly, communication between the drill string 
flow passage and the annular volume between sleeve 62 and the bores of 
elements 60, 55, and sleeve 77 is opened when O-ring 78 clears the 
recessed outer diameter groove 79 of sleeve 62. With sufficient downward 
movement of sleeve 62, the downwardly-facing shoulder 80 on the outer 
diameter of sleeve 62 will encounter abutting inner shoulder 81 of dump 
valve 82 and force seal 83 of dump valve 82 away from its seat 84. Wavy 
washer 81a is disposed abutting shoulder 81. This causes the accumulator 
48 precharged pressure to equalize with the drill string pressure above 
the blanking sub. Sleeve 77 is a sacrificial sleeve which protects the 
seat 84 of dump valve 82 from flow erosion, since it protrudes past the 
upper edge of dump valve 82 when the valve is unseated. Release of drill 
string pressure permits dump valve 82 biased by spring 82a, to reseat, 
while return spring 73 causes sleeve 62 to move back up and to cam around 
to follow the short stroke groove path 78a of slot 68 on the next downward 
reciprocation of sleeve 62. Slow reapplication of drill string pressure 
causes sleeve 62 to move downwardly so that fluid communication is 
established with the poppet check valve assembly 88 mounted in the lower 
end of middle barrel 55. A very low excess pressure will overcome poppet 
spring 89 to permit charging the accumulator to the maximum pressure 
obtained in the drill string before the drill string pressure is bled off. 
Release of the drill string pressure allows sleeve 62 to return upward as 
it cams around to the start of another long groove path. After sleeve 62 
is returned upward, the wireline blanking sub (not shown) is sheared out 
and retrieved to the surface. The pressure-balanced spring-biased sleeve 
valve 62 then remains closed until reactivated by running of another 
blanking sub and the appropriate pressure cycling. 
By way of review, the bore of sleeve valve 62 is closed by a wireline 
blanking sub latched therein, and the drill string is pressured to move 
sleeve valve 62 downward according to a long groove path of cam groove 68 
until it unseats valve 82 to balance pressure with the accumulator. Next, 
drill string and accumulator pressure are reduced and valve 82 closes and 
sleeve valve 62 moves back up when pressure across the blanking sub is 
approximately balanced. When the drill string pressure is again increased, 
sleeve valve 62 again is moved down, but not as far since it is controlled 
by a short groove path of cam groove 68. This time, drill string pressure 
flows through poppet check valve 88 to recharge the accumulator, after 
which the wireline blanking sub is sheared out and removed. The above 
operation may be repeated as necessary. 
While a preferred embodiment of apparatus has been described and shown in 
the drawings, many modifications thereof may be made by a person skilled 
in the art without departing from the spirit of the invention, and it is 
intended to protect by Letters Patent all forms of the invention falling 
within the scope of the following claims.