Well tool control system and method

Field of the invention

This invention relates generally to methods and apparatus for controlling the surface operation of downhole equipment, and more particularly to a new and improved in-ground equipment control system which is responsive to command signals having a particular signature downhole in fluids. reacts and causes actuation of a valve actuator, which in turn opens or closes a valve element.

Background of the invention

It has become common practice to provide well monitoring operations such as the testing and evaluation of the formation by means of pressure controlled valve members such as those shown in Nutter Patent Re. 29,638, issued May 28, 1978, and assigned to the assignee of this invention to perform. Other related devices are disclosed, for example, in Nutter Pat. Nos. 3,823,773, issued July 16, 1974, and No. 3,986,554, issued 19. No. 4,403,659, issued September 13, 1983, No. 4,474,242, issued October 2, 1984; and No. 4,576,234, issued March 18, 1986, all assigned to the assignee of this invention were shown. All of these devices are valve assemblies that can be actuated in response to changes in pressure in fluids and are either in the annulus between the tubing string and the casing or in the casing. These devices have been used very successfully in testing cased boreholes where a high pressure signal can be reliably fed into the fluids in the annulus. However, some very deep, cased wells are not tested on pressure controlled equipment because the operating pressure could exceed the burst limit of the casing. In addition, the testing of un-drilled (uncased) wells has not been done with standard pressure controlled equipment because of the risk that the operating pressures could cause burglary of the exposed formations and loss of their load capacity. Certain types of valve elements, such as circulation valves, required relatively long actuation times due to the complicated consequences of annulus or tubing pressure changes required to control the device from the closed to the open position and reclose, if necessary. For such arrangements, an increased length to a point where a typical combination of tester (sampler), sampler, and circulation valves has a total length that may well exceed 100 feet is significant. Of course, the higher complexity of the valve systems generally reduces reliability and increases the risk of errors. Nevertheless, there is a continuing need in the industry to increase the number of monitoring operations that can be performed underground during a single run of the log set in the wellbore. With the above limitations and the industry's needs in mind, the downhole control system disclosed and claimed in this application has been invented.

Document US-A-4,712,613, which represents the prior art referred to in the preambles of claims 1 and 9, respectively, discloses a blow-out preventer suitable for underground installation in a fluid-filled wellbore is provided. The downhole valve includes a signal receiving unit adapted to receive a coded mud pulse signal generated from an accumulator over days and transmitted into the wellbore. The signal receiving unit controls a plurality of solenoid valves.

A general object of the present invention is to provide a novel and improved in-use control system which can be operated in response to signals due to changes in low pressure, and thus applies to all types of wells, including deep cased wellbores and non-drilled wellbores.

Summary of the invention

In accordance with one aspect of the present invention, there is provided a wellhead control system located underground in a fluid-filled borehole to control the operation of equipment forming part of the apparatus, the system including overhead signal generating means for introducing pressure pulses into the wellbore fluid for transmission through this to the device, Controller means in the apparatus for detecting the transmitted pulses and one or more signal generating means controlled by the controller means and connected to control the operation of the apparatus, characterized in that the signal generating means for forming each of the pulses is a low pressure pulse of predetermined amplitude and duration; are formed to form a plurality of different input stimuli from these pulses, each input stimulus having an associated signature determined by the amplitude and / or duration of the pulse or pulses forming it, and in that the controller means comprise transducer means responsive to the input stimuli for generating electrical signals representative of the respective signature, and a control circuit is provided for interrogating the output of the converter means to determine whether a signature-representative signal is present on them and, upon detection of such a signature-representative signal, to actuate the control device or devices and thus to actuate the devices in response thereto.

According to another aspect of the invention, there is provided a method of controlling the operation of a portion of a downhole apparatus that is located underground in a fluid-filled wellbore, the method comprising generating overlying pressure pulses in the wellbore fluid for transmission therethrough the device, Detecting the transmitted pulses in the device and controlling the devices in response to the detected pulses and characterized in that the generating step comprises forming each of the pulses as a low pressure pulse of predetermined amplitude and duration and forming a plurality of different input stimuli from the pulses, each stimulus being associated with, by the amplitude and / or duration of the impulse or impulses that make it up, has certain signature, and the detection and control steps include receiving the input stimuli at the downhole device and translating them into electrical output signals representative of such signatures, interrogating the output signals to determine whether a signature-representative signal is generated, and detecting such signature Representative signal, the operation of the devices in response to it.

In a preferred embodiment of the invention, the apparatus includes a tubular housing having a pressure responsive actuator spindle which is capable of moving therein between longitudinally spaced positions. The longitudinal movement of the actuator spindle is used, for example, to cause the displacement of an associated valve member between the open and closed positions with respect to a flow passage, which passage is either within the housing or through the side wall thereof. The spindle has a piston surface on which the pressurized working fluid acts to develop a longitudinal force, the working fluid from a chamber in the housing at a pressure substantially equal to the hydrostatic pressure of the borehole fluids surrounding the housing is supplied.

The working fluid is selectively supplied by the actuator piston through a system of control valves that can be actuated in response to a battery powered controller located in the housing. The actuator spindle remains in one of its positions until the controller receives a command signal. According to one aspect of the invention, such a command signal is a series of low pressure pulses fed into the well annulus overnight, such signal having a "signature" or characteristic by which it can be identified. For example, but not by way of limitation, each low pressure pulse may have a peak that lasts for a certain amount of time. When a command signal is received, the controller causes the system of control valves to assume various states wherein the pressurized working fluid is supplied to the actuator piston for developing the required force to cause the actuator to shift from one position to the other. The actuator spindle is returned to its original position in response to another command signal, during which return the working fluid is stored in a low pressure chamber in the housing. In one embodiment, the return of the actuator spindle is effected by a spring, while in another embodiment, the return is enforced by a pressurized working fluid acting on the opposite side of the actuator piston. In the second embodiment mentioned, the control valve system and the controller, when the actuator spindle is pushed back into its starting position, ensure that the working medium is filled from the opposite side of the piston into the low-pressure chamber.

The duration of each low pressure pulse in the command signal may be relatively short, for example 30 seconds. If a sequence of such pulses is used, only a few seconds have to elapse between injected pulses. The pressure pulses are relatively small in amplitude and may be on the order of only about 500 psi (pounds per square inch) or less. The power required to operate the system is provided only underground, with the pressures required to displace the actuator spindle being derived exclusively from an underground source, namely the level of hydrostatic pressure of the downhole fluids. Since only low pressure pulses or signals are fed into the annulus to cause an adjustment of the downhole valves, the invention can be applied to all wells, including deep cased wellbores, as well as non-drilled wellbores. By using the system of the present invention, a large number of valve element cycles are possible, allowing a greater number of well monitoring operations to be performed with a single entry into the wellbore. The total operating time is reduced, avoiding complicated and long-lasting consequences of high-pressure feeds into the annulus. The invented system disclosed herein is relatively simple and compact and allows for a significant shortening of the lengths of the prior art device components. In addition, the reliability increases.

Brief description of the drawings

The present invention has further objects, features and advantages, which will become more apparent in connection with the following detailed description of the preferred embodiments, taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a schematic view of a drillstem test rig (drill stem) disposed in a well to be tested; FIG.

Fig. 2 is a schematic drawing of the hydraulic components of the present invention;

FIG. 3 is a block diagram of the control components used to operate the hydraulic system of FIG. 2; FIG.

Fig. 4 is a pressure-time diagram for illustrating a command signal comprising a series of low-pressure pulses,

5A-5F are longitudinal sections showing the same portions of a circulation valve component of a drillstem test string constructed in accordance with this invention as side cracks (the upper portion of FIG. 5D is rotated relative to the lower portion of FIG To show pressure passages in section),

Figs. 6 and 7 are transverse cross sections taken along lines 6-6 and 7-7 in Fig. 5D and Figs

Fig. 8 is a sectional view of a device string component having a ball valve element which may be used to control the formation fluid flow through a central passage of a housing in response to the operation of the control system of the present invention.

Detailed Description of the Preferred Embodiments

First, in FIG. 1, a drillstem tester string suspended in a wellbore 10 on a drill pipe or casing 11 is shown. The testers include a typical packer 12 which serves to seal off the wellbore portion to be tested from the hydrostatic pressure of the fluids above it in the annulus 13, and a main test valve unit 14 which serves to direct the flow of formation fluids from the sealed portion into the well To enable or prevent pipe string 11. The main valve 14 is closed during the lowering of the devices, so that the interior of the casing forms a low pressure region, in which the formation fluids can flow. After the single slide 12 is set, the valve 14 is opened for a relatively short flow period while the pressures in the wellbore are decreasing. Thereafter, the valve 14 is closed for a longer flow period time during which build up of pressure in the foreclosed wellbore is recorded. Other equipment such as a pot and safety connection may be coupled between the check valve 14 and the single slide 12, but they are not shown in the drawing as they are well known. A perforated suction tube 15 is connected to the lower end of the spindle of the single slide 12 to allow the fluids in the wellbore to penetrate into the equipment string, while typical inboard and outboard pressure recording devices 16, 17 are provided to receive pressure data as the test progresses.

A circulation valve 20 selected to illustrate the principles of the present invention is connected in the apparatus string above the main check valve unit 14. As shown schematically in FIG. 2, the valve unit 20 includes an elongate tubular housing 21 having a central flow passage 22. A valve actuator 23 is slidably mounted in the housing 21 and includes a spindle 24 having a central passage 25 and an outwardly directed annular piston 26 which is sealed by a sealing ring 28 against a cylinder 27 in the housing 21. Additional sealing rings 29, 30 are used to prevent leakage between the cylinder 27 and the passage 22. The sealing rings 29, 30 are preferably engaged with the same diameter so that the spindle 24 is in equilibrium with respect to the fluid pressures in the passage 22. A coil spring 32 located in the housing under the piston 26 presses against an upwardly directed surface 33 at the lower end of the cylinder 27 and against a downwardly directed surface 34 of the piston 26. The spring 32 produces a force for upward displacement of the spindle 24 with respect to the housing 21. The annular region 35 in which the spring 32 is disposed contains air at atmospheric or other low pressure. The cylinder portion 36 above the piston 26 is connected via an opening 37 to a hydraulic line 38 through which oil or other hydraulic fluid is supplied under pressure. Sufficient pressure acting on the surface 40 of the piston 26 causes the spindle 24 to shift downwardly against the resistance applied by the coil spring 32, while a release of this pressure enables the spring to translate the spindle upwardly to its initial position , The opposite movement of the spindle 24, as will be described below, is used to actuate any of the various valve elements which control the flow of fluids through either the central passage 22 of the housing 21 or through one or more lateral openings through the wall of the housing 21 Taxes.

The source of pressurized hydraulic fluid is a chamber 42 filled with hydraulic oil. As will be explained below, the chamber 42 is pressurized by the hydrostatic pressure of the well fluids in the well annulus 13 acting on a floating piston that applies that pressure to the oil. A conduit 43 leads from the chamber 42 to a first solenoid valve 44 which includes a spring-loaded, normally-closed valve member 45 which engages a seat 46. Another conduit 47 leads from the seat 46 to a conduit 48 which is connected to a first servo valve 50 which is used to control communication between a hydraulic line 51 connected to the actuator line 38 and a line 52 also from the high pressure chamber 42 goes out, serves. A second solenoid valve 53, which also includes a spring-loaded, normally-closed valve member 54 which is engageable with a seat 55, is located in a conduit 56 which communicates the conduits 47, 48 with a storage chamber 57 which is initially free of liquids and thus contains air at atmospheric or other low pressure.

The servo valve 50 includes a shuttle member 60, which carries sealing rings 61, 62 and is urged by a coil spring 63 to a position in which it closes the cylinder conduit 51. However, when the second solenoid valve 53 is opened by energization with electric current, the pendulum 60 changes to its open position shown, whereby the hydraulic fluid behind the pendulum 60 can be sucked through the lines 48 and 56 to the low pressure storage chamber 57. With the servo valve 50 open, the pressurized oil from the chamber 42 flows through the lines 52, 51, and 38 into the barrel area 36 above the actuator piston 26. The oil pressure, which is approximately equal to the hydrostatic pressure, pushes the actuator spindle 24 against the tension of the piston Coil spring 32 down.

The hydraulic system, as shown in FIG. 2, also includes a third normally closed solenoid valve 65 disposed in a conduit 66 leading from the chamber 42 to a conduit 67 connected to the pressure side of a second servo valve 68 connected is. The servo valve 68 also includes a pendulum 70 which guides sealing rings 71, 72 and is urged upward by a coil spring 74 to its closed position, the pendulum closing an exhaust duct 73 leading to the storage chamber 57. A fourth normally closed solenoid valve 76 is located in a conduit 77 which connects the pressure line 67 of the servo valve 68 to the storage chamber 57. The solenoid valve 76 includes a spring-loaded valve member 78 which cooperates with a seat 79 to prevent flow in the closed position toward the storage chamber 57 via the conduit 77. Similarly, the third solenoid valve 65 includes a normally-closed, spring-loaded valve element 80 which cooperates with a seat 81 to prevent oil flow from the high-pressure chamber 42 via the line 66 to the servo input line 67, unless it, as shown, by the supply of its coil is opened with electric current. When the solenoid valve 65 is opened, the oil supplied under pressure to the input side of the servo valve 68 causes the pendulum 70 to close the accumulator line 73. Although high pressure may prevail in the conduit 82 which connects the outside of the pendulum 70 to the conduits 51 and 38, the pressures in the conduits 67 and 82 are equal whereby the spring 74 keeps the pendulum closed above the conduit 73. Although a functionally separate servo valve is shown, it should be understood that a single three-way servo valve could be used.

In order for the driving spring 32 to push the actuator spindle 24 upward from the position shown in FIG. 2, the first solenoid valve 44 and the fourth solenoid valve 76 are energized and the second solenoid valve 53 and the third solenoid valve 65 are de-energized simultaneously. By doing so, solenoid valves 53 and 65 change to their normally closed positions while valves 44 and 76 open. The opening of the valve member 45 allows the pressures on the opposite sides of the pendulum 60 to equalize, causing the pendulum 60 to be displaced by its spring 63 to the position in which it closes the cylinder conduit 51. The valve member 54 of the solenoid valve 53 closes against the seat 55 to prevent the pressure in the chamber 42 from escaping via the conduit 56 into the storage chamber 57. The closing of the valve element 80 and the opening of the valve element 78 connects the servo line 67 via the line 77 with the storage chamber 57, so that the cylinder high pressure in the lines 38 and 82 forces the pendulum 70 to move against the tension of the spring 74 and to open the connection between the lines 82 and 73. Thus, as the spring 32 expands and the actuator spindle 20 pushes up to complete a downward and upward movement cycle, the hydraulic fluid in the barrel portion 36 is aspirated above the piston 26 into the storage chamber 57. The solenoid valves 44, 53, 65 and 76 may each be energized in pairs as described above to achieve additional actuator agitation cycles until all the hydraulic oil has been transferred from the chamber 42 to the storage chamber 57. The actuator spindle 20 is of course held either in its upper or in its lower position when all solenoid valves are de-energized.

As will be described below with reference to the various drawings forming FIG. 5, the pressurized working fluid may be supplied to the region 35 below the piston 26 to force the upward movement of the actuator spindle 24. In this case, instead of the spring 32, a further group of servo valves and solenoid valves, as shown in Fig. 2, could be used.

A control system for selectively energizing the solenoid valves 43, 53, 65 and 76 is shown schematically as a functional block diagram in FIG. The various components shown in block diagram are all installed in the walls of the housing 21 of the circulation valve 20, as will be explained below in connection with Figs. 5A-5F. One or more batteries 90 feed a power supply assembly 91 that provides electrical power to a command receiver assembly 92, a controller assembly 93, and a magnetic driver assembly 94. The command signal fed into the well annulus 13 for days is sampled by a transducer 95 which provides an electrical signal representative of that signal to the receiver assembly 92. The receiver assembly 92 is for converting a low level electrical signal from the converter 95 into an electrical signal of a particular format that may be interrogated by a controller assembly 93 to determine whether at least one or preferably two or more electrical signals representing the command signature are present Output of the sensor 95 are present. If and only if so, controller assembly 93 provides an output signal that triggers the function of driver assembly 99 that causes the drivers to supply selected pairs of solenoid valves 43, 53, 65, and 76 with electrical power are indicated schematically in the drawing with SV-1 and SV-2.

4 is a pressure-time diagram showing one embodiment of the command signal that triggers the valve function. As shown, the signal is in the form of a series of low pressure pulses P-1, P-2. The pressure pulses P-1, P-2 are fed into the fluids in the well annulus 13, as shown in Fig. 1, via the conduit 18 over days, with each pressure pulse being fed for a certain period of time and then being exposed. Such time periods are indicated in the drawing with T-1 and T-2. These discrete pressure pulses are, as indicated, separated by short time intervals, however, the lengths of these intervals are not indicative in the embodiment shown. The levels of the injected pressure pulses are relatively low and, for example, must not exceed 500 psi. The duration of the peaks T-1, T-2 of each pulse may be quite short, for example 30 seconds. However, as long as the receiver 92 is not supplied with an output signal from the converter 95 which contains voltages which rise to a certain level and are held at that level for the predetermined time periods, the controller 93 does not provide an output signal to the driver 94. In this manner are spurious or random pressure increases or pressure fluctuations, among others may occur when the unit is lowered, does not discriminate and trigger any function of the control system. To trigger the controller 93, a single pressure pulse P-1 could be used, but a sequence of at least two such pulses is preferred.

Of course, some of the features of the present invention described so far serve to minimize energy requirements to a minimum. For example, the solenoid valves are normally closed devices that only require energy when energized and thereby open. The controller assembly 93 provides no output as long as its interrogation of the output of the receiver 92 does not indicate that a command signal having a known signature has been sampled by the converter 95. Of course, the driver 94 will not supply power to a selected solenoid valve pair unless signaled by the controller assembly 93 indicates that this should be done. In either case, only as much electrical power is required as is needed to power the circuit assemblies and to energize the solenoid valves, as the forces that displace the actuator spindle 24 are either from the pressure differential between the hydrostatic pressure and the pressure in the storage chamber or output the spring 32 are derived. Thus, the power drained from the batteries 90 is quite low, so that the system can be operated for extremely long underground periods.

The structural details of a circulation valve unit 20 constructed in accordance with the invention are shown in more detail in Figs. 5A-5F. The circulation valve unit 20 includes an elongate tubular housing, generally designated 100, which includes an upper subassembly 101 having one or more circulation ports 102 extending therethrough. The threads 103 at the top of the subunit 101 are used to connect the housing 100 to the lower end of the tubing 11 or other device strand component above. The upper subassembly 101 is bolted at 99 (FIG. 5B) to the upper end of an adapter sleeve 104, which in turn is bolted at 105 to the upper end of a tubular storage chamber member 106. The element 106 is connected by means of screw connection via an adapter sleeve 108 with a tubular oil chamber element 107 (FIG. 5C), while the lower end of the element 107 is screwed at 109 (FIG. 5D) to the upper end of a servo and solenoid valve subunit 110. Subassembly 110 is bolted to another tubular member 111 (FIG. 5E) that includes pressure transducers 95 and all of the various circuit assemblies described in connection with FIG. 3 have been explained. Finally, at 112, the lower end of member 111 is bolted to the upper end of a battery tray subassembly 113 which receives one or more batteries 90 in appropriate recesses 114 in its walls. The lower end of the battery subunit 113 has API stud threads 115 (FIG. 5F) with which the lower end of the housing 100 can be connected, for example, to the upper end of the main test valve assembly 14.

Referring again to FIGS. 5A and 5B, the upper housing subunit 101 is provided with stepped-face inner surfaces defining a central passage 22, a seal bore 117, and a cylinder bore 118. An actuator spindle 24 having an outwardly directed piston portion 26 is slidably disposed in the subunit 101 and carries sealing rings 30, 28 and 29 respectively against the seal bore 117, the cylinder wall 118 and a lower seal bore 120 formed in the upper end portion of the adapter 104 is, seal. The diameters of the sealing engagement of the rings 30 and 29 are preferably the same, so that the spindle 24 is balanced with respect to the internal fluid pressures. An oil passage 37 leads via an opening 122 to the cylinder portion 36 above the piston 26 and is connected via the openings 123 to a secondary passage 37A which extends down into the adjustment subunit 104. The seals 124 prevent leakage at the openings 123 and behind the threads 99.

In the embodiment shown in Fig. 2, a downward force on the spindle 24 develops due to the oil compressed in the cylinder portion 36, wherein an upward force is applied to the spring 32 located in an atmospheric chamber 35. In the embodiment shown in FIGS. 5A-5F, due to the compressed oil, a downward force also develops on the spindle 24, which is selectively applied to a cylinder portion 126 below the piston 26. Of course, both embodiments are within the scope of the present invention. Where compressed oil is used to develop a force in both longitudinal directions, as indicated on the left side in Fig. 5B by solid and dashed lines, another oil passage 125 extends downwardly from the barrel portion 126 below the piston 26 into the adapter subassembly 104th Although not discussed in detail, the manner in which the passage 125 extends downwardly into the housing 100 toward the control valve subunit is substantially equal to that described with respect to the passage 37.

The oil passage 37A merges at the openings 126 in another passage 128 which is formed in the upper portion 128 of the connecting pipe 130. Section 128 carries sealing rings 131-133 to prevent fluid leakage, while the lower end of passage 37B is connected by a certain length to small diameter mating sleeve 134 extending downwardly through an elongated annular cavity 57 between the outer wall of the connecting tube 130 and the inner wall of the chamber subunit 106 is formed extends. The cavity 57 forms the above with reference to FIG. 2 described low-pressure storage chamber and may have a relatively large volume, in the embodiment shown, for example, 150 cubic inches. The lower end of the plug-in tubing 134 connects to the vertical passage 37C (Figure 5C) in the lower portion 136 of the connecting tube 130 which, in turn, passes at the openings 139, which are suitably sealed as shown, into a passage 37D which extends extends down into the adaptation subunit 108. Near the lower end of the subassembly 108, the passage at the openings 137 recirculates into an oil passage 37E which extends down into the wall of the oil chamber subunit 107.

An elongate tube 140 is concentrically disposed in the subunit 107 and formed to form another annular cavity 42 between the outer wall surface of the tube and the inner wall surface of the subunit . The cavity 42 forms the high pressure oil chamber shown schematically in FIG. 3 and may also have a volume close to 150 cubic inches. The outer seal rings 143-146 seal against the chamber subassembly 108 near the openings 137, while the inner seal rings 147 seal against the upper end portion of the tube 140.

A piston 150 for transmitting the hydrostatic pressure in the form of a ring member, which guides inner and outer seals 156, 157, is slidably disposed within the annular chamber 42 and is in its upper end when the chamber is filled with oil. The region 151 above the piston 150 communicates with the well annulus outside of the housing 100 via one or more radial openings 152. As shown in FIG. 5D, the lower end of the chamber 42 is defined by the top surface of the upper portion 153 of a servo and solenoid valve subassembly 110, with the inner and outer seal rings 155, 154 preventing the escape of fluid. The chamber 42 is filled with a suitable hydraulic oil for days, and when the devices are lowered into a fluid-filled well, the piston 150 transfers the hydrostatic pressure of the well fluids to the oil in the chamber 42, whereby the oil always has a pressure, which is substantially equal to this hydrostatic pressure. On the other hand, the storage chamber 57 initially contains air at atmospheric or other relatively low pressure. The difference in these pressures is thus available to generate forces which cause the valve actuator spindle 24 to be vertically displaced in one direction, as will be described in greater detail below.

As shown in Fig. 5D, the passage 37E at the openings 160 sealed by rings 161, transitions inwardly into a vertical passage 82 which extends down into the valve subunit 110 and has a transverse bore 165 formed therein the wall of the subunit 110 is formed, cuts. The bore 165 receives the servo valve assembly 68, which has been generally described with reference to FIG. As shown in FIG. 6 The cylinder sleeve 166 has an outer annular recess 168, which is connected to the passage 67, and openings 168, so that the recess with the inner bore 170 of the Sleeve communicates. As shown, sealing rings are provided to seal the cylinder sleeve 166 with respect to the bore 165. A cup-shaped oscillating piston 172 with a closed outer end 173 can sealingly slide with respect to the cylinder sleeve 166, while a coil spring 174 pushes the piston 172 out of the sleeve 166 to the outside. A tubular insert 175 threaded into the bore 165 to hold the cylinder sleeve 166 in place has an outer annular recess 176 and openings 177 connecting the body passage 82 to the interior of the insert 175. The outer end of the insert 175 is closed by a sealing plug 178. As shown, various sealing rings are provided to seal the insert 175 with respect to the bore 165 and its inner end portion with respect to the piston 172. A seal sleeve 180, which is urged by a coil spring 181 against the piston 172, is slidably mounted in the insert 175. As shown, the sleeve 180 has a bore 182 to allow undisturbed oil flow. The main purpose of the sleeve 180 is to cover the O-ring 183 and hold it in its groove as the piston 172 moves backward into the cylinder space 170. The inner end portion of the cylinder sleeve 166 may be slotted at 184 to allow undisturbed oil flow through the passage 73 as the piston 172 telescopes from its closed position, as shown, to its open position where it is inserted into the cylinder bore 170 is being moved. The passage 73 is widened within the walls of various components of the housing 100 to a point at which its upper end opens into the storage chamber 57. This structure is not shown, but is similar to the manner in which the passage 37 is formed, except that it is offset at an angle thereto. The other, with reference to FIG. 2 A generally described servo valve assembly 50 is housed in a further transverse bore 185 in the wall of the valve subassembly 110 at the same height as the servo unit 68, as shown in FIG. Since unit 50 is structurally identical to unit 68, a detailed description of the various parts of these units will not be repeated to simplify the disclosure. The various passages that intersect the bore 185 are the cylinder passage 51, the supply passage 52, and the servo pressure port 48.

The pair of solenoid valves 65 and 76 operatively associated with the servo valve 68 are housed in transverse bores 190 and 205 in the wall of subunit 110, as shown in FIG. The valve assembly 65 includes a sealing plug 191, which is threaded into the bore 190 as shown, with the plug carrying an annular seat member 192 having a central opening 193. The bore 194 of the plug 191, downstream of the orifice 193, is connected via a passage 195 to an outer, annular groove 196 which is cut through a passage 67 'in the valve sub 110, which communicates with the passage 67, as shown which communicates with the servo valve 68 communicates. O-rings at appropriate locations seal against leakage of fluid, as shown. The seat member 192 cooperates with a valve member 197 at the end of a plunger 200 to prevent flow through the opening 193 when the member is pressed against the seat member and to allow such flow when the member is in the open, off Seat member is remote position, as shown in Fig. 7. The plunger 200 is biased by a coil spring 202 against the seat member 192, which acts against the base of a conical socket 203, which is screwed into the subunit 110 at 204. A coil 205, which is secured to the socket 203 surrounds the plunger 200 and, when energized by electrical current, causes the plunger 200 and valve member 197 to move away from the seat member 192 and back to the open position. When the spool 205 is not energized, the spring 202 forces the plunger and the valve member to move forwardly to the closed position, in which a tapered face of the member engages a tapered seating surface 192 to close the opening 193 close. As indicated by dashed lines, the passage 66, in the flow direction behind the seat ring 192, opens into the bore 190, while the passage 67 'leads away from the bore region in the vicinity of the groove 196. The passage 66 leads in the housing 110 upwards and into the open connection to the high-pressure chamber 42.

As shown in Fig. 7, is housed on the opposite side of the unit 65 of the subunit 110 in a transverse bore 205 a completely identically constructed solenoid valve unit 76, which thus need not be described in detail. The bore 205 is, as shown, cut through the passages 67 "and 77, wherein the passage 67" is a further extension of the passage 67. The passage 67 "intersects the bore 205 at a location upstream of the seat member of the valve unit 76, while the passage 77 intersects the bore adjacent the outer annular recess of the valve unit, which is downstream of the seat member up into the housing 100 to a position where it communicates with the storage chamber 57, as shown in Fig. 5C.

The other pair of solenoid valves 44 and 53, operatively associated with the servo valve 50, are located in bores identical to bores 190 and 205 but, as shown, are located at a different axial height in subassembly 110 near the bottom of FIG. 5D , Since they are of identical construction, these units are also neither shown nor described in detail to keep the disclosure simple. The respective bores in which the units 44 and 53 are housed are cut through the passages 43, 47 and 56, 47 ', respectively, as generally described with reference to FIG. Of course, corresponding electrical conductors pass through correspondingly designed bores, slots and high-pressure feed-through connectors (not shown) of the magnet driver assembly 94, which are shown schematically in FIG. 3 is shown, to the respective coils of the solenoid valve units 44, 53, 65, 76th

The cylinder passage 125 (FIG. 5B), which is connected to the region 126 below the piston 26, leads down into another set of control valve components, including a pair of servo valves, each operatively connected to a pair of solenoid valves in the same arrangement as shown in FIG 2 is assigned. This group of elements is located in subunit 110 below the group shown near the bottom of FIG. 5D. Again, the individual elements are not described in detail here in order to shorten and simplify the disclosure.

As shown in FIG. 5E, the pressure transducer 95, which is mounted near the lower end of the control subunit 110, is connected to the well annulus 13 outside the housing 100 via a vertical opening 210 and a radial opening 211 and thus is capable of To sense annulus pressures and to provide an output signal indicative of these pressures. An elongated annular cavity 212 is formed between the inner wall of the housing member 111 and the outer wall of a sleeve 214, the upper end of which is screwed and sealed to the lower end portion of the subunit 110 as shown. Annular cavity 212 receives various circuit assemblies 91-94, shown in block diagram form in FIG. 3, namely the receiver, controller, drivers, and power supply assemblies. The electrical conductors 215, which pass through a suitable channel in a tubular fitting 216, connect the power supply assembly 91 to one or more storage batteries 90 located in another cavity 218 near the bottom of the device. The cavity 218 is like the cavity 212 formed between the housing member 113 and the outer wall of a central tube 219. The lower end of the sleeve 214 and the upper end of the tube 219 are, as shown, bolted to the fitting 216 and sealed. The lower end of the tube 219 is sealed against the lower portion 220 of the housing member 112 with rings 221, as shown in Fig. 5F. The entire housing assembly 100 has a central fluid passage 22 which extends through the respective holes of the various tubes, sleeves, subunits and housing members.

As mentioned above with reference to FIG. 2, the actuator spindle 24 is moved up and down in response to selective energization of the solenoid operated valves with respect to the housing 21. Where the present invention is embodied in a circulation valve 20 which serves to control communication between the passageway 22 and the well annulus 13, the associated valve member may take the form of a sliding sleeve which, as shown in FIG. 5A is formed by the upper portion 220 of the actuator spindle 24. The sleeve 220 carries an upper seal ring assembly 221 which, together with the seal ring 30, prevents flow through the side openings 102 in the housing sub unit 101 when the sleeve and actuator spindle are in the upper position in which the sleeve 220 covers the openings 102. In the lower position of the sleeve 220 and the actuator 24, the openings 102 are opened for a fluid flow, so that borehole fluids from the annulus 13 in the casing or the drill collar 12 can be returned by applying pressure to the well annulus 13 over days. Positive information feedback from underground confirms the opening of the openings 102 since a sudden or abrupt annulus pressure change occurs at the moment the openings are opened. This pressure change can be detected by a suitable means in the pressure supply line 18 over days.

If it is desirable to reseal the openings 102 so that other monitoring operations such as acidifying the wellbore section below the single slide can be performed, another sequence of low pressure pulses is fed into the annulus 13 via line 18 over the course of the day causing that the controller 93 provides the driver 94 with a signal for energizing the solenoid valves 44 and 76 and for switching off the power supply for the solenoid valves 53 and 65. As a result, the sleeve 220 and the actuator 24 are pushed upward in response to the high pressure acting on the lower surface 34 of the piston 26 to position the seal assembly 221 above the openings 102, as described above. The circulation valve 20 remains closed until another command signal having a predetermined signature is fed to the annulus 13 to cause the spindle 24 to descend.

An embodiment of the present invention utilizing a valve element to control fluid flow through the central passageway 22 is shown in FIG. Here, the upper end of the actuator spindle 24 is provided with a pair of laterally offset, upstanding arms 225 having eccentric lugs 226 which engage radial slots 227 in the outer sidewalls of a ball valve element 228. The ball valve 228 rotates about the axis of the pivot 230 on its opposite sides between an open position in which the through hole 231 of the ball member with the passage 22 is axially aligned, and a closed position in which its outer spherical surface 232 with a seat counterpart 233 at the lower end of a seat sleeve 234 is engaged. In the closed position, a composite seal ring assembly 235 prevents the escape of fluid. As described above, the spindle 24 is moved up and down on command to open and close the ball member accordingly. Positive feedback of the position of the ball element 228 is obtained by dayly monitoring of the pressure in the tubing 11. The use of a ball member 228 provides a valve structure which, in the open position, provides undisturbed vertical passage through the devices so that further downhole equipment such as strand-breaking, deep-drilling and pressure-recording devices can be lowered through the equipment string in rope work. The ball member 228 also provides, in the open position, a large flow area that is beneficial in testing particular wellbores. As can be appreciated by one skilled in the art, the ball member 228 may serve as a main check valve, safety valve, or as part of a scanner.

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During operation, the valve and operating system is arranged as shown in the drawing, with the chamber 42 being filled with a suitable hydraulic oil until the floating piston 150, as shown in Fig. 5C, is at the top of the chamber. The chamber 42 may then be pressurized to cause the pendulum 60 to open so that the lines 52, 51 and 38 are filled with oil, whereupon the solenoid valves 44 and 65 are temporarily opened so that the lines 43 , 47 and 48 as well as lines 66 and 67 can also fill with oil. The storage chamber 57 initially contains only air at atmospheric pressure. The actuator spindle 24 is in its upper position, in which the circulation openings 102 are closed by the spindle portion 220, and is held by the return spring 32, if this, as shown in Fig. 2, is used in this upper position. In the actuator embodiment shown in Fig. 5B, due to seal friction, the spindle remains in its upper position because otherwise the spindle has a pressure balancing construction. The unit 20 is then connected to the equipment string and lowered together with this in the borehole to the test depth. During operation of the devices, the piston 150 transfers the hydrostatic pressure to the oil in the chamber 42, so that the oil pressure in the chamber is always substantially equal to the hydrostatic pressure of the fluids in the annulus 13.

At the test depth, the instrument strand is brought to a standstill and the single slide 12 is set by suitable pipe manipulation to separate the wellbore section below it from the wellbore fluid column which is above it in the annulus 13. In order to start a test, the main valve 14 is opened for a short flow period to lower the pressure in the section separate from the wellbore, and thereafter for a closing period in which the fluid pressures can build up, with the intention that the formation fluids flow into the Drill hole below the single slide, opened. The pressure recording devices 16, 17 are used to create graph records of the pressure over the time elapsed during the test. If desired, suitable known means may be used to provide data readout during the test.

In order to clear the tubing string 11 of formation fluids accumulated during the test, the circulation valve 20 is opened in the following manner. A command signal consisting of a series of low-pressure pulses, each of which has a certain duration, is fed to the fluids present in the well annulus 13 via line 18. The pressure pulses are detected by the transducer 95 whose output is coupled to the amplifier or receiver 92. The receiver 92 converts the electrical low level signals from the converter 95 into an electrical signal having a particular format. The formatted signal is polled by the controller 93 to determine if electrical signals representing the command signature are present. If so, the controller 93 triggers the function of the magnet driver 99, thereby powering selected pairs of solenoid valves. As a result, the actuator spindle 24 is moved up or down at the command from the surface. When the pair 53, 65 is energized, the low pressure in the storage chamber 57 communicates with the back of the servo valve pendulum 60, causing it to open, whereby the hydrostatic pressure of the oil in the chamber 42 on the upper surface 40 of the Actuator piston 26 is exercised. The excitation of the solenoid valve 65 provides a balance of pressures on either side of the pendulum 70 so that its spring 74 holds the pendulum above the conduit 73, closing it. The difference between the hydrostatic fluid pressure and the atmospheric pressure thus acts on the actuator piston 26, which generates a downward force to drive the actuator spindle 24 down against the tension of the return spring 32. This movement positions the valve seal assembly 221 below the side openings in the housing 21, with the solenoid valves 53 and 65 being de-energized by the driver 94 in response to signals from the controller 93 after a suitable time delay which guarantees complete extension of the spindle 24. Thereafter, pressure may be applied to the annulus 13 for days to cause all of the fluids in the tubing string 11 to be routed back to the surface where they may be discharged into a suitable container for testing and analysis or, if desired, disposed of. If the test is to be terminated at this point, the single pusher 12 is released and the tool string is pulled out of the borehole, so that the pressure recording diagrams can also be checked and analyzed.

If further testing or monitoring activities are to be done without removing the equipment from the wellbore, the circulation valve 20 is closed again. For this purpose, another sequence of low-pressure pulses is fed into the fluids in the well annulus for days. These pulses, as described above, activate the controller 93, which causes the driver 94 to energize the other solenoid valve pair 44, 76. The opening of the solenoid valve 44 equalizes the pressures around the servo valve pendulum 60 so that its spring 63 forces the pendulum to the closed state above the conduit 51. When the solenoid valve 53 is no longer energized, it moves into its normally closed position against the seat 55. The opening of the solenoid valve 76 reduces the pressure on the spring side of the servo tube 70, whereby the pressure in the line 82, the pendulum is set in its open position in which a connec tion between the line 82 and the storage line 73 is made. Of course, the solenoid valve 65, when not energized, moves to its normally closed position. The return spring 32 pushes the actuator spindle 24 upwards, wherein the volume of oil in the chamber portion 36 is displaced into the storage chamber 57. By repeatedly feeding command signals into the fluids in the annulus 13, the circulation valve 20 can be repeatedly opened and closed.

The cycles of the downward and upward movement of the actuator spindle 24 may also be used to rotate the ball element 228 shown in FIG. 8 between its open and closed positions with respect to the flow passage 22. Thus, in conjunction with the control system of the present invention, a ball member may be used as the main check valve 14 or as the scanner safety valve means. Each valve component of the test string may have its own control system that operates in response to a different signature command signal. Additionally, a control system may be used to actuate a number of different valve components, wherein the driver 94 is provided to control the energization of a plurality of pairs of solenoid valves associated with the respective valve components.

Although the present invention has been described in conjunction with Drillstem testers, it has application to other downhole equipment such as shooting systems and firing triggers used in deep well drilling, single pusher mounts and safety valves, to name but a few of the devices in which the Longitudinal movement of a spindle in a housing can be used to activate or control another device.

Although a command signal consisting of one or more low-pressure pulses with a predetermined duration of the peak level has been addressed here in several places, it is of course possible to use low-pressure signals with other signatures. For example, the command signal could have a rise time characteristic, or the composite signal could have a sequence of time windows, with the presence or absence of a pressure pulse in the various windows forming a signature.

It has become clear that a novel and improved in-day appliance control system has been disclosed. The system responds to low pressure pulses injected into downhole fluids and thus applies to all types of wells, including deep cased and uncased (uncased) wells. The power source and command module is included in the device and designed for minimum power consumption due to the use of normally-closed solenoids and the use of underground hydrostatic pressures to generate forces that cause cyclic movement of an actuator. Long operating times as well as complicated consequences of high pressure feeds can be avoided. The system enables device designs that are very compact, simple and reliable. Since the disclosed embodiments can be subject to certain changes and modifications without departing from the inventive concept, it is the aim of the following claims to cover all such changes and modifications as come within the scope of these claims.