Surface controlled subsurface safety valve

A pilot valve system for a subsurface safety valve operated by control fluid pressure from the surface including a pilot valve connected with the control fluid line to the subsurface safety valve and into the well production string immediately above the safety valve to bypass the control fluid pressure directly into the tubing string and dump the control fluid pressure from the subsurface safety valve into the tubing string directly above the valve to minimize the time delay between control fluid pressure reduction and the safety valve closure. Three embodiments of the pilot valve are disclosed. One embodiment is operable by electrical energy from the surface. The other embodiments are operable by acoustic energy and radio waves, respectively. Also disclosed is a minimum backlash latch assembly for releasably locking the pilot valve, or other well tools, along a well bore in a receptacle such as a side pocket mandrel.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to subsurface safety valves for controlling flow in 
wells, such as oil and gas wells, and more particularly relates to a 
subsurface safety valve controlled from a remote location, such as at the 
surface and which responds in a minimum time. More specifically, the 
invention relates to a remotely controllable pilot valve for a 
conventional subsurface safety valve operated by control fluid pressure 
communicated from the surface. 
2. History of the Prior Art 
It is well known to use subsurface safety valves for control of fluid flow 
such as oil and gas in a tubing string in a well bore. Such a subsurface 
safety valve of the wireline retrievable type is illustrated and described 
in U.S. Pat. No. 3,703,193 issued Nov. 21, 1972. The safety valve shown in 
such patent has a hydraulically operated piston for holding the valve open 
in response to hydraulic fluid pressure conducted to the valve through a 
control fluid conductor extending to the surface end of the well bore. It 
will be obvious that for the operator piston of such a subsurface safety 
valve to move upwardly for closing the valve, the piston must raise a 
column of control fluid equal to the distance between the subsurface 
safety valve and the surface end of the well bore. Substantial time can be 
involved in the closure of such a subsurface safety valve due to this 
column of control fluid. One solution to the problem of the time delay 
required for the subsurface safety valve to react against the column of 
control fluid has been the use of a pilot valve connected downhole near 
the subsurface safety valve between the source of control fluid pressure 
and the safety valve, for shutting off the control fluid pressure to the 
valve and releasing the control fluid pressure in the safety valve into 
the tubing string immediately above the safety valve, thus, eliminating 
the need for the safety valve piston to lift the column of control fluid 
between the safety valve and the surface. Such a pilot valve is 
illustrated and described in U.S. Pat. No. 4,119,146 issued Oct. 10, 1978. 
The pilot valve shown in U.S. Pat. No. 4,119,146, is hydraulically 
operated and responds to a change in the control fluid pressure. Thus, the 
response time of the pilot valve is necessarily long because of the time 
required for a hydraulic pressure signal change to travel from the surface 
to the pilot valve and because the valve must lift the column of hydraulic 
control fluid a short distance upwardly to move from a first lower 
position to a second upper position for shutting off control fluid 
pressure to the safety valve and releasing the safety valve control fluid 
pressure into the tubing string above the safety valve. Also, the pilot 
valve of U.S. Pat. No. 4,119,146 does not open the control fluid line to 
the surface into the tubing string. Often subsurface safety valves are 
located at depths of several thousand feet in a well bore. Thus, the time 
for even a pilot operated subsurface safety valve located at a depth of 
several thousand feet to react to a change in control fluid pressure can 
be substantial even in the case of a pilot valve which releases the 
control fluid pressure into the tubing string. 
SUMMARY OF THE INVENTION 
It is, therefore, a principal object of the invention to provide a new and 
improved subsurface safety valve operated in response to a pilot valve 
controlled from a remote location to effect essentially instant operation 
of the safety valve. 
It is another object of the invention to provide a pilot valve for 
controlling hydraulic control fluid pressure to a subsurface safety valve 
to shut-off control fluid pressure to the safety valve and dump the 
pressure into the well bore above the safety valve for minimizing the 
closing time of the safety valve. 
It is another object of the invention to provide a pilot valve for 
subsurface safety valve of the character described which is responsive to 
electrical signals transmitted from a remote location. 
It is another object of the invention to provide a pilot valve for a 
subsurface safety valve which is operated in response to electromagnetic 
signals such as radio waves transmitted from a remote location. 
It is another object of the invention to provide a pilot valve for a 
subsurface safety valve which is operated in response to an acoustic 
signal communicated to the pilot valve from a remote location. 
It is another object of the invention to provide a pilot operated 
subsurface safety valve which is operated from a remote location 
independently of control fluid pressure communicated to the safety valve 
from the surface. 
It is another object of the invention to provide a pilot valve for 
controlling a subsurface safety valve which reacts more quickly to close 
the safety valve than presently known subsurface safety valve control 
systems. 
It is another object of the invention to provide a minimum backlash type 
latch assembly to releasably lock a well tool in a well bore. 
In accordance with the invention, there is provided a pilot valve to be 
located in a flow conductor near a subsurface safety valve to release 
control fluid pressure from the safety valve and from between the pilot 
valve and the surface into the tubing above the safety valve to permit the 
safety valve to close. The pilot valve includes an electrically operated 
flow control valve which may be operated by an electric line from the 
surface, by acoustic signals from the surface, or by radio waves from the 
surface. Further, in accordance with the invention, there is provided a 
minimum backlash latch assembly for releasably locking a well tool, such 
as the pilot valve, along a well bore in a receptacle such as a side 
pocket mandrel.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
FIG. 1, shows a well installation including a valve system embodying the 
features of the invention. As illustrated, a well 30 is cased with a 
string of casing 31 in which a string of production tubing 32 is supported 
through a well packer 33 sealing the annulus between the tubing and the 
casing above a producing formation, not shown. Flow through the producing 
string is controlled by valves 34 and 35. A subsurface safety valve 40 is 
installed in the production string for shutting off the fluid flow 
responsive to control fluid pressure communicated to the safety valve 
through a line 41 extending to a control fluid operating manifold 42 at 
the surface. In accordance with the invention, the control fluid line 41 
is connected with the safety valve 40 and a pilot valve 43 which releases 
control fluid pressure to the safety valve while dumping the control fluid 
pressure into the tubing 32 above the safety valve in response to an 
electrical signal communicated through a cable 44 from a surface power 
unit 45 which may be operator controlled or respond to a variety of safety 
conditions such fire, flow line rupture, and the like. The electrical 
control of the pilot valve provides substantially quicker response and a 
closing of the subsurface safety valve than conventional subsurface safety 
valves which react to a reduction of control fluid pressure through the 
line 41. The electrically operated pilot valve 43 responds instantly to a 
signal through the line 44 opening the portion of the control fluid line 
41 between the pilot valve and the safety valve 40 releasing the control 
fluid pressure in that short section of the line into the tubing 32 so 
that the subsurface safety valve closes essentially instantly. The 
electrically operated pilot valve does not have to wait for the pressure 
reduction signal to travel from the surface and does not have to lift the 
full column of control fluid between the safety valve and the surface for 
the safety valve to close. 
The relationship between the pilot valve 43 and the subsurface safety valve 
40 is schematically illustrated in FIG. 2. Well fluids from the formation 
50 below the packer 33 flow in the production tubing string 32 to the 
surface through the valve assembly 51 of the subsurface safety valve. The 
valve assembly 51 is biased closed by a spring and is held open by control 
fluid pressure in a cylinder assembly 53 communicated to the safety valve 
through the control fluid line 41. The control line 41 includes a filter 
53a and a check valve 54. The control line 41 splits into branch lines 41a 
leading to the subsurface safety valve control cylinder 53 and branch line 
41b connected into the tubing string 32 above the safety valve through a 
valve assembly 55 of the pilot valve 43. The valve assembly 55 includes a 
spring 60 biasing the pilot valve open and a solenoid 61 connected with 
the electric line 44 to the surface. The solenoid 61 closes the pilot 
valve when energized. During the operation of the well installation of 
FIG. 1 and when well fluid flow through the safety valve 40 to the surface 
through the tubing string 32 is desired, control fluid pressure is 
provided from the manifold 42 through the line 41, through the filter 53a 
and the check valve 54, into the branch line 41a to the safety valve 
control cylinder 53. The piston in the cylinder assembly 53 is urged to 
the left against the spring 52 opening the safety valve for fluid flow 
from the formation 50 upwardly through the production string 32 to the 
surface. The solenoid 61 of the pilot valve is energized from the surface 
unit 45 through the electrical line 44 shifting the pilot valve assembly 
55 to the left closed position against the spring 60 so that control fluid 
pressure from the line 41 cannot flow upwardly in the branch line 41b. 
When it is desired to shut-in the well by closing the subsurface safety 
valve, or safety conditions such as fire dictate shutting-in the well, 
electrical power from the unit 45 through the line 44 is shut off 
deenergizing the solenoid 61 in the pilot valve assembly 55. The spring 60 
shifts the pilot valve assembly to the open position illustrated in FIG. 2 
so that fluid in the control line 41 may flow through the branch line 41b 
of the pilot valve assembly 55 and into the production tubing string 32 
above the subsurface safety valve. The release of the control fluid 
pressure at the pilot valve directly into the tubing string 32 immediately 
lowers the pressure of the control fluid in the safety valve assembly 53 
so that the spring 52 closes the subsurface safety valve 40 thereby 
shutting-in the well. The control fluid pressure in line 41 is dumped 
through the pilot valve into the production string above the safety valve. 
To reopen the subsurface safety valve, the solenoid 61 is reenergized 
through the line 44 closing the valve assembly 55 of the pilot valve 43 
and control fluid line pressure is reestablished in the line 41 through 
the filter 53a and the check valve 54 into the branch lines 41a and 41b. 
Since the pilot valve assembly 55 is now closed, the fluid cannot flow 
upwardly through the pilot valve into the production string 32. Thus, the 
control fluid pressure increases through the branch line 41a into the 
cylinder assembly 53 of the subsurface safety valve urging the piston of 
the cylinder assembly 53 to the left against the spring 52 reopening the 
valve assembly 51 of the safety valve so that production fluids may again 
flow upwardly in the production string 32. 
As will be understood in more detail hereinafter, in alternate embodiments 
of the invention the pilot valve may be operated by electromagnetic 
signals such as radio or acoustic signals transmitted down the well bore. 
Referring to FIGS. 3A-3C inclusive, the electrically operated pilot valve 
43 is releasably supported in a receptacle 70 of a side pocket mandrel 71 
connected in the production tubing string 32. The pilot valve is 
releasably locked in the receptacle by a limited backlash latch assembly 
72 connected with the pilot valve and operable by a wireline for running 
and pulling the pilot valve. The latch assembly 72 is connected with the 
pilot valve by a flow coupling 73 provided with a T-shaped flow passage 74 
opening into an annulus 75 within the receptacle 70 communicating through 
side port 80 with the main bore through the side pocket mandrel 71. The 
flow passage 74 directs bypassed power fluid from the pilot valve through 
the coupling 73 to the side port 80 and into the bore of the side pocket 
mandrel. 
Referring to FIG. 3B, the pilot valve 43 includes a top sub 81, the 
solenoid 61, the valve assembly 55, a central body 82, and an electrical 
plug contact assembly 83. The top sub is screwed on the lower end of the 
connector 73 and supports an external annular seal assembly 84 which seals 
around the pilot valve with the bore surface of the receptacle 70. The top 
sub has a central bore 85 providing a longitudinal flow passage through 
the sub into the flow passage 74 of the connector 73. A check valve 86 is 
secured in the reduced upper portion of the bore 85 to prevent backflow of 
fluids from the side pocket mandrel bore into the safety valve assembly. 
The lower end portion of the bore 85 is enlarged to accommodate electrical 
wiring connections to the solenoid 61. The central body portion of the 
pilot valve includes an upper section 82a and a lower section 82b. The 
upper section threads on the lower end of the top sub 81 and has a 
cylindrical chamber 90 which opens at a lower end to an internally 
threaded bore 91 communicating with a flow passage 92. The enlarged bore 
90 accommodates the solenoid 61 and the valve assembly 55 which threads 
into the bore 91. An annular ported spacer 93 is positioned between the 
upper end of the solenoid 61 and the lower end of the top sub 81. An 
O-ring 94 fits between the spacer and the lower end edge of the top sub to 
provide a downward bias to maintain the solenoid at a lower most position 
and absorb shock. The solenoid 61 fits in spaced relation within the bore 
90 to provide an annulus for the electrical wiring to the solenoid and 
fluid flow around the solenoid into top sub bore 85. The lower body 
section 82b screws on the lower end of the upper body section 82a and is 
fitted along a lower end portion on the upper end portion of the plug 
assembly 83. A filter 95 is fitted within the housing section 82b between 
the upper end of the plug 83 and the lower end of the body section 82a to 
filter fluids flowing into the bore 92 of the upper body section and into 
the bore portion 91 into the valve assembly 55 to protect the valve from 
abrasives. Two circumferentially spaced, longitudinal, electrical wire 
feed-through assemblies 100 are disposed within the bore of the lower 
housing section 82b threaded along upper ends into the lower end of the 
upper body section 82a each to accommodate a wire 101 leading to the 
solenoid 61. 
The valve assembly 55 and solenoid 61 of the pilot valve 43 is an available 
product manufactured by Sterer Manufacturing Company, 4690 Colorado Blvd., 
Los Angeles, Calif. 90039 under the part number 70109-1. The electrical 
wire feed-through connectors 100 also are standard available assemblies 
capable of functioning under high temperatures and pressures and 
manufactured and sold by Kemlon Products and Development, 6310 Sidney, 
Houston, Tex. 77021 under the trademark Duo-Seel and sold under the 
general product designation K-16BM. It will be recognized that other 
available solenoid operated valve assemblies and electrical wire 
feed-through connector systems may be used. 
The plug contact assembly 83 shown along the lower portion of FIG. 3B and 
in enlarged detail in FIGS. 4-14 inclusive, provides an insertable 
electrical male plug on the lower end of the wireline removable pilot 
valve. The plug assembly 83 provides electrical contact with an electrical 
female receptacle contact assembly 110 secured with and forming a part of 
the side pocket mandrel receptacle 70 in which the removable pilot valve 
fits. The plug 83 includes and is connected into the lower end of the body 
portion 82b by a plug mount 111 having a central bore 112 for fluid flow 
through the upper end of the plug assembly. The plug mount also has two 
circumferentially spaced bores 113 for the wires 101 and a downwardly 
opening blind bore 114 to accommodate the upper end of an alignment and 
anti-rotation rod 115 to properly align and maintain the alignment of the 
various components which make up the plug assembly 83. A tubular retaining 
screw 120 is threaded along an upper end portion into the internally 
threaded lower end portion of the bore 112 of the plug mount 111 to 
provide a flow passage through the bore 120 of the retaining screw into 
the bore 112 of the plug mount and to hold the various parts of the plug 
assembly 83 together. A tubular insulator sleeve 123 fits on the retaining 
screw 120 between the upper threaded portion of the screw and the flange 
122. Two plug contact bodies 124 are mounted in tandem spaced relation 
along the insulator sleeve 123 between annular insulated rings 125. A 
longitudinally fluted contact ring 130 is mounted on each of the contact 
bodies 124. Design details of the contact bodies 124 are shown in FIGS. 
9-11. FIG. 12 shows an assembly of one of the contact rings 130 mounted on 
a contact body 124. The details of the insulator rings 125 are shown in 
FIGS. 13 and 14. Referring to FIGS. 9-11, each of the contact bodies 124 
is made of an electrically conductive material and provided with a central 
bore 140 sized to receive the insulator tube 123 and circumferentially 
spaced longitudinal slots 141 having a semi-cylindrical shaped and opening 
into the bore 140. An internally threaded set screw bore 142 is provided 
for a set screw, not shown, for attaching the ring 130 to the body. Two of 
these slots 141 each accommodates one of the electrical wires 101 while 
the third slot 141 receives the alignment rod 115. A blind bore 143 is 
aligned with and spaced from one of the slots 141. A slot 144 is provided 
in an end face of the body 124 connecting the adjacent longitudinal slot 
141 with the blind bore 143 for securing one of the wires 101 in 
electrical contact with the body 124. As shown in FIG. 10 a lateral set 
screw bore 145 is provided for a set screw 150 into the blind bore 143 so 
that an end of the set screw may clamp an end of the wire 101 to the body 
124 in the blind bore 143. As evident in FIG. 11 an end of the wire 101 is 
bent one hundred eighty degrees (180.degree.) from the direction it 
extends in the slot 141 so that the end of the wire loops around into the 
bore 143 to be clamped to the body 124 by the set screw 150 to make good 
electrical contact therewith. External annular end flanges 151 retain the 
fluted contact ring 130 against longitudinal movement on the body 124. As 
evident in FIG. 12 the fluted contact ring 130 has a plurality of 
circumferentially spaced longitudinally extending spring-like contact 
portions 130a. The ring 130 is held against rotation on the body 124 by a 
set screw 152 threaded in the hole 142 of the body. The spring action of 
the ring portions 130a provide a tight electrical contact between the plug 
assembly 83 and the receptacle 110 for each of the wires 101. The 
insulator rings 125 each has a bore 153 for the insulator tube 123 and 
holes 154 which align with the body slots 141 for the alignment rod and 
for the wires 101. The insulator rings 125 and the insulator tube 123 
electrically insulate the bodies 124 from each other and from the 
retaining screw 121 so that each of the bodies 124 may conduct electricity 
from the contact ring 130 to the wire 101 clamped to the body 124. A 
tubular nose member 160 fits on the tube 123 between the retaining screw 
flange 122 and the lower insulator ring 125 for holding the components of 
the plug 83 tightly together longitudinally when the retaining screw 120 
is tightened. The nose member 160 has a central bore 161 sized to received 
the tube 123 and a blind upwardly opening hole 162 for the lower end of 
the alignment rod 115. It will be apparent that as the plug 83 is 
assembled the alignment rod 115 is inserted into the plug mount 111 at the 
upper end through the insulator rings 125 and the bodies 124 and into the 
plug nose 160 at the lower end to hold all such components against 
rotation when the plug is finally assembled and the wires 101 are 
connected with the bodies 124. As will be evident from FIG. 3B, two wires 
101 are connected between the plug 83 and the solenoid 61. One wire is 
connected with each of the bodies 124 as described and illustrated in 
FIGS. 10 and 11. Each of the wires extends upwardly through separate holes 
and bores provided in the bodies 124 and the spacers 125. Each of the 
wires extends through one of the connectors 100 upwardly into the upper 
body section 82a around the solenoid 61 and into the upper end of the 
solenoid as illustrated in the upper portion of FIG. 3B. 
The side pocket mandrel receptacle electrical contact assembly 110 is 
illustrated in detail in FIGS. 3B and 3C, FIG. 4, FIGS. 5-8, and FIGS. 15 
and 16. The assembly 110 has a housing 170 which fits in a lower end 
portion of the bore through the side pocket mandrel receptacle 70 against 
the downwardly facing internal annular shoulder 171 around the receptacle 
bore. The housing 170 screws along the lower end portion on the upper end 
of a wire feed-through member 172 which carries an O-ring seal 173 for 
sealing with the bore surface of the receptacle and is held in place by a 
retainer ring 174 threaded into the lower end of the receptacle bore as 
shown in FIG. 3C. An insulator sleeve 175 is positioned within the bore of 
the housing 170 held in place by the wire feed-through member 172. 
Electrical contact rings 180 are mounted in spaced relation within the 
sleeve 175 separated by insulator rings 181. The contact rings 180 are 
positioned longitudinally for engagement by the fluted rings 130 on the 
plug 83 when the pilot valve is installed in the side pocket mandrel. A 
wire guide body 182 is disposed within the bore of the insulating sleeve 
175 between the wire feed through 172 and the lower contact ring 180. The 
wire guide body holds the two contact rings 180 and the insulating rings 
181 within the sleeve 175 in the relationship shown in FIG. 4. Details of 
the structure of the wire guide 182 and the contact rings 180 are shown in 
FIGS. 5-7 and 15 and 16, respectively. Referring to FIGS. 5-7, the wire 
guide 182 is formed of an electrically insulating material and is provided 
with three circumferentially spaced longitudinal slots 183 one of which 
opens to deeper slot 184 which communicates at an upper end thereof as 
shown in FIG. 6 with an upwardly opening central bore 185 provided in the 
wire guide. The slot 184 also communicates with a downwardly opening 
central bore 190 of the wire guide. Two of the slots 183 communicate with 
angular side holes 191 and 192 in the guide. The hole 191 opens from the 
lower end portion of one of the slots 183 into the lower end of bore 185. 
The hole 192 opens from the bore 185 through the upper wall section of the 
guide into the slot 183. Each of the sets of slots 183 and the holes 191 
and 192 provide a path for a wire 193 for providing electric power to the 
receptacle contact rings 180. The reduced lower end portion of the wire 
guide 182 is spaced within the wire feed-through 172 providing an annulus 
between the wire guide and the wire feed-through so that the two wires 193 
may pass through the annulus upwardly through the holes 191 into the bore 
185 and outwardly from the bore 185 in the holes 192 into the vertical 
slots 183 through which the wires extend to the two contact rings 180. One 
of the contact rings 180 is shown in detail in FIGS. 15 and 16. The ring 
is made of electrically conducting material and provided with external 
longitudinal half cylinder shaped slots 193 which are aligned 
circumferentially with the slots 183 of the wire guide 182. The insulator 
rings 181 are also provided with corresponding longitudinal half cylinder 
shaped slots, not shown, to accommodate the wires 193. In the assemblied 
relationship of the parts of the receptacle 110 as shown in FIGS. 3B and 
3C and FIG. 4, the vertical slots in the wire guide 182 and the electrical 
contact rings 180 and the insulating rings 181 are all in alignment so 
that two of the wires 193 pass upwardly through the aligned slots as seen 
in FIG. 8. An upper end portion of one of the wires 193 is soldered or 
welded to one of the rings 180 as shown in FIG. 8. The other wire 193 
extends to the other contact ring 180 to which it is also soldered or 
welded along an upper end portion. In the third set of aligned 
longitudinal slots along the wire guide 182 and the contact rings 180 and 
the insulating rings 181, a half cylinder shaped alignment rod 194 is 
positioned to hold the components of the receptacle assembly 110 against 
rotation. As shown in FIG. 3C, the cable 44 from the surface includes the 
electrical wires 193 connected into the contact rings of the receptacle 
110. The cable 44 is connected into a coupling 195 secured on a tube 200 
which is connected along an upper end portion into a downwardly opening 
bore 201 of the wire feed through member 172 as shown in FIG. 3C. The 
branch line 41b of the hydraulic control fluid system connects along an 
upper end portion into a separate longitudinal bore 202 of the member 172 
opening at an upper end into the slot 184 of the wire guide 182 so that 
the fluid flow in the branch line 41b passes into the bore 185 of the wire 
guide 182. 
Referring to FIGS. 18-21, the latch assembly 72 is a limited backlash latch 
assembly for wire-line operation to releasably lock the pilot valve 43 in 
the receptacle 70 of the side pocket mandrel 71. Latch assembly 72 can be 
used to install various types of well tools, particularly those which are 
useful in a side pocket mandrel, but is not limited to use with such side 
pocket mandrel tools or the pilot valve 43. The latch assembly 72 has a 
body 250 enlarged along an upper head portion 251 which is provided with a 
downwardly and inwardly sloping stop shoulder 252 which supports the latch 
assembly within the receptacle 70 of the side pocket mandrel. The body has 
circumferentially spaced windows 253, a longitudinal bore 254, and an 
internal annular snap ring recess 255 above the windows. The body has an 
external annular recess 260 for an O-ring seal 261 to seal between the 
latch assembly body and the inner bore of the receptacle 70. The head 
portion 251 of the body has a pair of spaced transverse shear pin bores 
262 extending perpendicular to and spaced from the longitudinal axis of 
the body. Internally threaded set screw holes 263 are provided in the body 
head portion 251 intersecting the shear pin bores 262. A tubular inner 
mandrel 264 is slidably disposed in the bore of the body 251 for movement 
between an upper running position as illustrated in FIG. 18 and a lower 
locking position shown in FIG. 20. The mandrel 264 has an enlarged head 
265 providing a downwardly facing external annular stop shoulder 270 for 
engagement with the upper end of the head 251 of the body 250 limiting the 
downward movement of the inner mandrel in the body. A split snap ring 272 
is mounted in an external annular recess along the lower end portion of 
the inner mandrel 264 for engagement in the latch ring recess 255 of the 
body when the inner mandrel is at the lower locking position of FIG. 20 
and release position of FIG. 22. The inner mandrel has two laterally 
spaced half cylindrical lock pin recesses 273 each of which receives a 
shear pin 274 through the bores 262 of the body to releasably lock the 
inner mandrel at the running position shown in FIG. 18 within the body 
250. Each of the shear pins 274 is held in place by a set screw 275 
threaded through the bore 263 against the surface of the shear pin, FIG. 
19. An O-ring seal 280 in an external annular recess on the inner mandrel 
264 seals with the bore through the body 250 around the inner mandrel when 
the inner mandrel is at the locking and released positions of FIGS. 20 and 
22. A core 281 fits in sliding relation through the bore of the inner 
mandrel 264. The core is held in the running and locking positions of 
FIGS. 18 and 20 by a pair of laterally spaced parallel shear pins 282 
fitting through lateral shear pin recesses in the core and in the bores in 
the head 265 of the inner mandrel in the same relationship represented in 
FIG. 19 between the inner mandrel and the body. The shear pins 282 are 
each held in place by a set screw 283. A lug expander ring 284 is screwed 
on lower end portion of the core 281 to coact with circumferentially 
spaced locking lugs 285 mounted in the windows 253 of the body 250. The 
ring 284 has a graduated outside diameter providing an upper locking 
surface 284a and a lower release surface 284b. The lugs 285 are arcuate 
shaped as shown in FIG. 21 and have retaining ears 290 which keep the lugs 
from falling from the windows as apparent in FIG. 21. A handling head 291 
is screwed on the upper end of the core. A set screw 292 is threaded 
through the head against the surface of the upper end portion of the core. 
The lower end edge of the head is engagable with upper end edge of the 
inner mandrel head 265 during the running of the latch assembly and when 
the latch assembly is locked in the side pocket mandrel receptacle as in 
FIGS. 18 and 20. 
The latch assembly 72 is connected with the pilot valve 43 as illustrated 
in FIG. 3A by threading the lower end of the latch assembly body 250 on 
the connector 73. Suitable wire-line handling tools are used to run and 
pull the latch assembly and pilot valve by grasping the head 291 of the 
latch assembly. The latch assembly releasably locks the pilot valve in the 
side pocket mandrel receptacle by engaging the stop shoulder 252 on the 
body 250 with the internal annular stop shoulder 70a, FIG. 3A, at the 
upper end of the side pocket mandrel receptacle 70. The expansion of the 
lugs 285 to the position shown in FIGS. 3A and 20 engages the lugs with 
internal annular locking shoulder 70b at the upper end of the recess 75 in 
the receptacle 70. During the running of the latch assembly and pilot 
valve the lug expander ring 284 is at the upper position shown in FIG. 18 
being held by the shear pins 273 engaged between the inner mandrel 264 and 
the body 250 as represented in FIGS. 18 and 19. When the pilot valve and 
the latch assembly enter the receptacle bore and the shoulder 252 engages 
the receptacle shoulder 70a, a downward force is applied to the head of 
the latch assembly. The pins 274 are sheared releasing the inner mandrel 
264 to move downwardly so that the inner mandrel and the core 281 are 
shifted to the lower locking position of FIG. 20. The shoulder 270 on the 
inner mandrel engages the upper end edge of the body head 251 limiting the 
downward movement of the inner mandrel in the body. The downward movement 
of the expander ring 284 within the lugs 285 moves the enlarged locking 
surface 284a of the expander ring behind the lugs expanding the lugs 
outwardly to the locking positions in the windows 253 as represented in 
FIGS. 20 and 3A. At the lower end position of the inner mandrel the snap 
ring 272 expands into the body locking recess 255 locking the inner 
mandrel at the lower end locking position of FIG. 20. The expanded locking 
positions of the lugs 285 is also shown in FIG. 21. When release of the 
latch assembly is desired to remove the pilot valve 43 from the side 
pocket mandrel receptacle, an upward force is applied on the head 291 of 
the latch assembly core. The pins 282 are sheared releasing the core to 
move upwardly to the position shown in FIG. 22 at which the reduced 
surface portion 284b on the lug expander ring is aligned with the inside 
faces of the lugs so that the lugs may move inwardly to the release 
positions of FIG. 22. The upper end edge of the ring 284 engages the 
internal annular stop shoulder 254a around the bore of the body 250 above 
the windows so that upward forces applied to the head are transmitted 
through the core to the ring 284 which lifts the body 250 with the lugs 
285 upwardly. The shoulder 270 on the inner core head 265 is engaged by 
the upper end edge of the body so that the entire latch assembly 72 is 
lifted upwardly with the lugs 285 cammed inwardly to the release 
positions. The snap ring 272 remains engaged between the inner mandrel 264 
and the body 250 as shown in FIGS. 20 and 22. Among the principal features 
of the latch assembly 72 is limited backlash during the operation of the 
latch assembly. 
When the pilot valve 43 mounted on the latch assembly 72 is landed and 
locked in the side pocket mandrel receptacle 70 as illustrated in FIGS. 
3A-3C, the pilot valve electrical plug assembly 83 is stabbed into the 
electrical receptacle assembly 110 as shown in FIG. 3B. Limited backlash 
of latch assembly 72 is an important feature to maintain electrical 
contact between plug assembly 83 and receptacle assembly 110 and to 
minimize wear and damage which would result from relative movement. 
Electric power may then be applied from the surface through the cable 44 
upwardly in the two wires 193 to the contact rings 180 of the receptacle 
assembly. From FIG. 4 it will be evident that the contact rings 180 are 
insulated from each other and from the housing 170 of the assembly. The 
contact ring assemblies 130 on the plug 82 engage the contact rings 180 by 
means of the spring sections 130a on the contact ring. The contact rings 
130 are in electrical contact with the bodies 124 which are insulated from 
each other and from other metal parts of the plug assembly 82. Electric 
power from the bodies 124 is conducted through the wires 101 which extend 
through the connector 100 and upwardly into the member 81 to the solenoid 
61. Application of electric power to the solenoid closes the normally open 
valve assembly 55 so that the power fluid flow may not occur upwardly 
through the pilot valve from the branch line 41b which connects with the 
main power fluid line 41 leading to the surface manifold 42. As shown in 
FIGS. 3C and 4, the upper end of the branch line 41b communicates through 
the wire guide 182 into the lower end of the bore 121 of the electric plug 
assembly 83. The power fluid communication continues upwardly through the 
bore 112 into the bore 92 into the valve 55 which is closed when the 
solenoid is energized. Power fluid through the branch line 41a is 
communicated downwardly to the safety valve 40 opening the safety valve. 
Deenergizing the solenoid by cutting off power from the surface to the 
solenoid, for any reason, such as if the safety valve is to be 
intentionally closed, or if a safety condition causes the electrical 
system to respond by cutting off power, the deenergized solenoid permits 
the valve assembly 55 to move to its normal fail-safe open condition. 
Power fluid communication is then established through the valve assembly 
55 around the solenoid upwardly through the bore portion 85 in the member 
81 and the bore 74 in the connector 73 and outwardly in the annulus 75 
around the connection between the latch assembly 72 and the pilot valve. 
The power fluid flows outwardly through the port 80 into main bore through 
the side pocket mandrel thereby essentially instantly releasing power 
fluid pressure to the safety valve so that the safety valve will close in 
the normal manner. The signal which initiates closing the safety valve 
preferably also renders the surface unit 42 inoperative so that control 
fluid will not be pumped into the line 41 after the pilot valve opens. 
Since the pilot valve is electrically operated, the usual time required 
for the pressure signal change to be transmitted from the surface to the 
pilot valve is eliminated. The pilot valve and the safety valve do not 
have to react against the fluid flow resistance and hydrostatic pressure 
of the column of control fluid extending to the surface. The safety valve 
operating piston is opposed only by the small amount of power fluid 
present in the lines along the short distance between the safety valve and 
the pilot valve. 
Another pilot valve system incorporating the features of the invention for 
operation by electromagnetic waves, such as radio, or acoustic signals is 
illustrated in FIGS. 17A-17C. Referring to FIG. 17A, the latch assembly 72 
is shown connected to a pilot valve 300 by a connector 301 on which an 
annular seal assembly 302 is mounted for sealing within the receptacle 70 
around the pilot valve above the discharge of the pilot valve into the 
side pocket mandrel bore. The pilot valve 300 comprises a battery pack 303 
connected with an amplifier 304 and a signal transducer 305 for turning 
power on and off to the solenoid 61 operating the valve assembly 55. A 
side window 310 in the side of the side pocket mandrel 71 permits either 
electromagnetic or acoustic communication to reach the signal transducer 
from the surface end of the well bore. The valve 55 controls communciation 
between the power fluid branch line 41b and a side port 311 in the side 
pocket mandrel receptacle 70 for dumping the power fluid into the tubing 
string above the safety valve when the valve 55 is opened in response to 
an electromagnetic or acoustic signal from the surface. Such signal may be 
sent intentionally to close in the well or in response to a safety 
criteria such as fire. The use of a system responsive to electromagnetic 
or acoustic signals eliminates the need for lines other than the power 
fluid line from the surface to the pilot valve and the safety valve. 
Referring to FIG. 17A, the connector 301 is secured on the upper end of a 
pilot valve housing section 312 having a central bore in which the battery 
pack and amplifier are located. A plurality of batteries 313 are arranged 
in conventional end-to-end array and thus are connected in series. A 
spring 314 bears down on the upper end of the top battery. A retainer ring 
315 engages the lower end of the lower battery holding the batteries in 
place. An electrical contact member 320 mounted in an insulated housing 
321 is biased by a spring 322 upwardly against the central contact of the 
bottom battery. The insulated housing is supported in a tubular upper end 
section 323 of a mounting plate member 324 on which is secured the 
amplifier 304. The lower end of the housing section 312 is secured on the 
upper end of a second mounting member 325 which supports the signal 
transducer and is connected along a lower end portion, FIG. 17c, into the 
upper end of a valve housing section 330 having a central chamber in which 
the solenoid 61 and the valve assembly 55 are housed. Solenoid 61 is 
electrically connected with signal transducer or antenna 352 via amplifier 
304 and wires 331. A block diagram for this circuit is shown in FIG. 23. 
The housing section 330 connects into a bottom sub 332 on which a nose 
piece 333 is mounted. A central bore through the nose piece, the bottom 
sub, and the lower end portion of the housing section 330 provides 
communication from below the pilot valve into the valve assembly 55. A 
flow passage 334 and side port 335 in the body section 330 and the bottom 
sub provide communication to the side port 311 back into the mandrel main 
bore from the valve 55 so that the valve assembly 55 controls 
communication between the power fluid branch line 41b into the main bore 
through the side pocket mandrel. Annular seal assemblies 340 on the 
housing section 330 and the bottom sub 332 seal around the pilot valve 
body above and below the side port 311 into the side pocket mandrel. 
Referring to FIG. 23, the pilot valve 300 of FIGS. 17A-17C is operated in 
response to a transmitter 350 located at the surface and a receiver 351 in 
the pilot valve. The transmitter may be an acoustic signal or radio 
transmitter and the receiver is compatable with the surface transmitter 
for processing the received signals to operate the solenoid of the pilot 
valve. The transmitter is designed to respond to any suitable conditions 
for shutting-in the well, such as safety considerations which may include 
fire, rupture of a flow line, and any other situation which would require 
immediate closure of the subsurface safety valve. The receiver 351 and 
associated network are housed in the pilot valve 300 and include an 
antenna 352, the amplifier 304, a filter 353, a clock or oscillator 354, a 
frequency divider 355, with a logic network 360, and a relay 361 powered 
by the batteries 313 for operating the valve solenoid 61. The transmitter 
and receiver, whether radio or acoustic, are designed to operate in a 
fail-safe manner by applying power through the relay to the valve solenoid 
so long as the subsurface safety valve is to be held open and to shut-off 
power through the relay to the valve solenoid under all conditions which 
require closure of the safety valve. Such conditions may be safety 
considerations, the need to close the safety valve for well servicing, 
power failures, or any other circumstances which would demand shutting-in 
the well. Suitable available components are selected for a radio 
transmitter and a radio receiver and related circuitry to operate the 
relay in response to radio signals. Acoustic transmitters and receivers 
which may be used at the surface and in the pilot valve 300 are 
illustrated and described in U.S. Pat. Nos. 3,961,308 to Parker issued 
June 1, 1976, 4,073,341 to Parker issued Feb. 14, 1978, 4,147,222 to 
Patten, et al issued Apr. 3, 1979, and 4,314,365 to Peterson, et al issued 
Feb. 2, 1982. For example, referring to U.S. Pat. No. 3,961,308, the 
transmitter 51 of the patented device may be connected to the production 
tubing string 32 at the surface in the present system and the receiver 52 
of the patented device may be connected to the production tubing string 32 
in the vicinity of the pilot valve 300 with the receiver controlling the 
relay 361 as the receiver controls the motor control switch 80 of the 
patented device. U.S. Pat. No. 4,314,365 also shows an acoustic surface 
transmitter and a downhole receiver which may be incorporated in the 
present system. It is stated in U.S. Pat. No. 4,314,365 that the acoustic 
signals may be applied to production tubing and may be used to activate 
packers, valves, measuring devices, and the like. Thus, the system of U.S. 
Pat. No. 4,314,365 could be incorporated into the present valve system to 
operate the solenoid 61. Teachings of radio responsive circuitry which may 
be employed to operate the solenoid valve are found in U.S. Pat. Nos. 
3,011,114 to Steeb, Nov. 28, 1961; 3,199,070 to Baier Jr., Aug. 3, 1965; 
3,413,608 to Benzuly, Nov. 26, 1968; 3,436,662 to Kobayoshi, Apr. 1, 1969; 
and 3,438,037 to Leland, Apr. 8, 1969. It will be obvious that when 
operating the pilot valve 300 in response to acoustic or radio signals, 
the pilot valve will be opened to close the safety valve under all of the 
conditions discussed but also when electrical power to the solenoid 61 no 
longer available, such as when the batteries run down. 
It will be apparent from the foregoing description and from the drawings 
that a pilot valve for operating a subsurface safety valve is provided 
which responds to energy communicated to the pilot valve through an 
electrical line, radio waves or electromagnetic energy, or acoustic 
signals to essentially instantly release hydraulic control fluid pressure 
to the subsurface safety valve to close the valve without the time delays 
inherent in the time required for a hydraulic pressure signal to reach the 
pilot valve and for the pressure responsive components of the safety and 
the pilot valves to lift a column of power fluid extending to the surface. 
While particular preferred embodiments of the system of the invention have 
been described and illustrated, various changes may be made in the 
particular designs shown within the scope of the claims without departing 
from the invention.