|Publication number||USRE39583 E1|
|Application number||US 08/944,474|
|Publication date||Apr 24, 2007|
|Filing date||Oct 6, 1997|
|Priority date||May 26, 1988|
|Also published as||US4896722|
|Publication number||08944474, 944474, US RE39583 E1, US RE39583E1, US-E1-RE39583, USRE39583 E1, USRE39583E1|
|Inventors||James M. Upchurch|
|Original Assignee||Schlumberger Technology Corporation|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (11), Non-Patent Citations (2), Referenced by (36), Classifications (23)|
|External Links: USPTO, USPTO Assignment, Espacenet|
This application is a continuation-in-part of application Ser. No. 295,614 entitled “Multiple Well Tool Control Systems in a Multi-valve Well Testing System”, filed 1/10/89, which application is a continuation in part of application Ser. No. 243,565 filed Sept. 12, 1988, now U.S. Pat. No. 4,856,595, which is a divisional application of application Ser. No. 198,968 filed May 26, 1988, U.S. Pat. No. 4,796,699.
The subject matter of the present invention pertains to an automatic well tool control system, and, more particularly, to multiple well tool control systems in a multi-valve well testing system including a means for automatically controlling the well tool control systems in response to kickoff stimulus which may include a sensing of bottom hole pressure or a sensing of the output of a strain gauge responsive to a set down weight of the well tool apparatus.
Multi-valve well testing tools of the prior art such as the well testing tools disclosed in U.S. Pat. No. 4,553,589 entitled “Full Bore Sampler Valve Apparatus”, and in U.S. Pat. No. 4,576,234 entitled “Full Bore Sampler Valve”, are typically mechanical in nature in that one valve disposed in the tool is mechanically linked to another valve disposed in the tool. If it is desired to open the one valve, an operator at the well surface, upon opening the one valve, must expect the other valve to be opened or closed as well since the two valves are mechanically linked together. Therefore, the operation of one valve is not independent of the operation of the other valve, and when one valve in the tool is opened, other valves disposed in the tool must be opened or closed in a specific predetermined sequence. A more recent and innovative apparatus for performing such well service operations, embodying pressure controlled valve devices, is shown in application Ser. No. 198,968, filed May 26, 1988, now U.S. Pat. No. 4,796,699, entitled “Well Tool Control System”, assigned to the assignee of this invention, the disclosure of which is incorporated by reference into the specification of this application. In application Ser. No. 198,968 referenced hereinabove, a well testing tool is disclosed which is not totally mechanical in nature, rather, it embodies a microelectronics package and a set of solenoids responsive to the microelectronics package for opening or closing valve disposed in the tool. A set of solenoids embodied in the well tool of application Ser. No. 198,968 are energized by a microcontroller also embodied in the well tool, which microcontroller is responsive to an output signal from any type of sensor, such as a pressure transducer embodied in the tool that further responds to changes in downhole pressure created and initiated by an operator at the well surface. It is understood that the sensor may be responsive to other stimuli than downhole pressure. The solenoids, when energized in a first predetermined manner, open and close a set of pilot valves that permit a hydraulic fluid under pressure, stored in a high pressure chamber, to flow to another section of the tool housing where an axially movable mandrel is positioned. The fluid moves the mandrel from a first position to a second position thereby opening another valve in the tool (for example, a test valve or a reversing valve). When the set of solenoids are energized in a second predetermined manner, the hydraulic fluid, stored in the other section of the tool housing, where the movable mandrel is positioned, is allowed to drain from the housing to a separate dump chamber; as a result, the mandrel moves from the second position to the first position, thereby closing the other valve. In each case, the solenoids are responsive to an output signal from the microcontroller, which is, in turn, responsive to an output signal from the sensor, which is, in turn, responsive to changes in other input stimuli, such as changes in pressure in the well annulus. The change in input stimuli is created and initiated, each time, by the operator at the well surface. Therefore, an opening or closing of the other valve in the tool is responsive, each time, to a stimulus change signal (such as changes in downhole pressure) transmitted into the borehole by the operator at the well surface. However, application Ser. No. 198,968 discloses a well testing tool which includes one well tool control system for controlling the closure state of one valve. The above referenced well testing tool could also contain a plurality of well tool control systems for opening and closing a plurality of valves. In this case, two or more of the above well tool control systems and two or more corresponding valves would be embodied in a well testing tool. The two or more of such well tool control systems would open and close the two or more valves in response to predetermined input signals. An operator need only transmit into a borehole the two or more unique input signals corresponding to the two or more separate valves. As a result, the operation of one valve disposed in the tool would be performed totally independently of the operation of any other valve disposed in the tool. In the application Ser. No. 295,614, referenced above, a well testing system is disclosed including two or more well tool control systems interconnected respectively between two or more valves and a microcontroller. Whenever a valve must be opened or closed, the operator must transmit an input stimulus into the borehole, such as a pressure signal; the microcontroller generates its output signal in response to the input stimulus for energizing one of the control systems which then operates a particular valve. However, when it is desired to operate two or more valves in sequence, a separate input stimulus must be generated in the well testing system for each of the two or more valves. If suitable microcode were provided in the microcontroller, a plurality of openings and closings of the two or more valves in the tool could be accomplished automatically by the microcontroller upon execution of its own microcode in response to an initial kickoff stimulus generated in the well testing system, such as a sensing of a bottom hole pressure or a sensing of a strain gauge output sensitive to a set down weight of the well testing tool in the borehole.
Accordingly, it is a primary object of the present invention to automatically control the operation of multiple well tool control systems disposed in a well testing system by providing such control systems with a microcontroller including a processor and a memory, the memory storing a set of microcode which, when executed by the processor, automatically opens and closes a set of valves in the tool a predetermined number of times, in a predetermined sequence, in response to a predetermined initial kickoff stimulus.
It is a further object of the present invention to initiate execution of the microcontroller microcode in response to an output signal from a pressure transducer, which transducer senses a bottom hole pressure of the well fluids present in the well annulus below a packer.
It is a further object of the present invention to initiate execution of the microcontroller microcode in response to an output signal from a strain gauge, which strain gauge senses, for example, the set down weight of the well testing tool when situated in the borehole of an oil well.
It is a further object of the present invention to initiate execution of the microcontroller microcode in response to an output signal from a pressure transducer which senses annulus pressure above the packer, or in response to an output signal from a timer which counts down a predetermined time delay.
These and other objects of the present invention are accomplished be designing a set of microcode for incorporation in a memory chip resident on a microcontroller chip of multiple well tool control systems disposed in a well testing system. The microcontroller chip includes a processor portion and a memory chip, the novel microcode of the present invention being stored in the memory chip, such as a Read Only Memory (ROM). When an initial kickoff stimulus is received by the microcontroller chip, the processor portion of the chip executes the microcode stored in the memory chip. During execution of the microcode, the processor portion of the chip generates certain output signals which cause other valves in the well testing tool to open or close. The kickoff stimulus may be either an output signal from a pressure transducer indicative of a bottom hole pressure, in the well annulus below the packer in the borehole, or indicative of annulus pressure above a packer, or an output signal from a strain gauge indicative of a set down weight or a torque of the tool when the tool is disposed in a particular position in the borehole. When the processor portion generates the output signals in response to execution of its resident microcode of the present invention, a typical flow/shut-in test may be performed, or a test valve and reversing valve may be opened and closed in an exact preprogrammed sequence. As a result, the results of a test may be based on direct measurements of existing downhole conditions, the measurements being made directly due to the automatic execution of a set of microcode resident in the memory chip of a downhole microcontroller. Using this approach, there is no need to transmit signals from the surface, through the manipulation of pipe or annulus pressure to control the downhole tool, each time an operation is performed downhole. The changes for misrun caused by manipulation of the pipe or annulus pressure to control the test valve is greatly reduced. Furthermore, an exact preset test sequence may be completed and the chances for the commission of human error are greatly reduced (a distinct advantage in open-hole situations where approximately 80% of the test sequences are preset and inflexibly carried out).
Further scope of applicability of the present invention will become apparent from the detailed description presented hereinafter. It should be understood, however, that the detailed description and the specific examples, while representing a preferred embodiment of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become obvious to one skilled in the art from a reading of the following detailed description.
A full understanding of the present invention will be obtained from the detailed description of the preferred embodiment presented hereinbelow, and the accompanying drawings, which are given by way of illustration only and are not intended to be limitative of the present invention, and wherein:
The following detailed description is divided into three parts: (1) part A entitled “Well Tool Control System” which describes the well tool control system as set forth in prior pending application Ser. No. 243,565, filed Sept. 12, 1988, now U.S. Pat. No. 4,856,595; assigned to the same assignee as that of the present invention, which application Ser. No. 243,565 is incorporated herein by reference, application Ser. No. 243,565 being a divisional application of application Ser. No. 198,968, filed May 26, 1988, now U.S. Pat. No. 4,796,699, assigned to the same assignee as that of the present invention, which application Ser. No. 198,968 is also incorporated herein by reference; (2) part B which represents a continuation-in-part of prior pending application Ser. No. 243,565 referenced hereinabove in part A, and describes “multiple well tool control systems in a multi-valve well testing system” as set forth in prior pending application Ser. No. 295,614 filed 1/10/89, assigned to the same assignee as that of the present invention, which application is incorporated herein by reference; and (3) part C which represents a continuation-in-part of prior pending application Ser. No. 295,614 referenced hereinabove in part B, and describes “multiple well tool control systems in a multi-valve well testing system having automatic control modes”, in accordance with the present invention.
Referring initially to
A circulating valve 20 that has been chosen to illustrate the principles of the present invention is connected in the tool string above the main test valve assembly 14. As shown schematically in
The source of hydraulic fluid under pressure is a chamber 42 that is filled with hydraulic oil. As will be explained below, the chamber 42 is pressurized by the hydrostatic pressure of well fluids in the well annulus 13 acting on a floating piston which transmits such pressure to the oil. A line 43 from the chamber 42 leads to a first solenoid valve 44 which has a spring loaded, normally closed valve element 45 that engages a seat 46. Another line 47 leads from the seat 46 to a line 48 which communicates with a first pilot valve 50 that functions to control communication between a hydraulic line 51 that connects with the actuator line 38 and a line 52 that also leads from the high pressure chamber 42. A second solenoid valve 53 which also includes a spring loaded, normally closed valve element 54 engageable with a seat 55 is located in a line 56 that communicates between the lines 47, 48 and a dump chamber 57 that initially is empty of liquids, and thus contains air at atmosphere on or other low pressure.
The pilot valve 50 includes a shuttle element 60 that carried seal rings 61, 62, and which is urged toward a position closing off the cylinder line 51 by a coil spring 63. However when the second solenoid valve 53 is energized open by an electric current, the shuttle 60 will shift to its open position as shown, hydraulic fluid behind the shuttle 60 being allowed to exhaust via the lines 48 and 56 to the low pressure dump chamber 57. With the pilot valve 50 open, pressurized oil from the chamber 42 passes through the lines 52, 51 and 38 and into the cylinder region 36 above the actuator piston 26. The pressure of the oil, which is approximately equal to hydrostatic pressure, forces the actuator mandrel 24 downward against the bias of the coil spring 32.
The hydraulic system as shown in
In order to permit the power spring 32 to shift the actuator mandrel 24 upward from the position shown in
As will be described below with reference to the various drawings which constitute
A control system for selectively energizing the solenoid valves 43, 53, 65 and 76 is shown schematically in
It will be recognized that a number of features of the present invention described thus far coact to limit power requirements to a minimum. For example, the solenoid valves are normally closed devices, with power being required only when they are energized and thus open. The controller board 93 does not provide an output unless its interrogation of the output of receiver 92 indicates that a command signal having a known signature has been sensed by the transducer 95. Then of course the driver 94 does not provide current output to a selected pair of the solenoid valves unless signalled to do so by the controller board 93. In all events, the only electrical power required is that necessary to power the circuit boards and to energize solenoid valves, because the forces which shift the actuator mandrel 24 are derived from either the difference in pressure between hydrostatic and dump chamber pressures, or the output of the spring 32. Thus the current drain on the batteries 90 is quite low, so that the system will remain operational for extremely long periods of downhole time
The structural details of a circulating valve assembly 20 that is constructed in accordance with the invention are shown in detail in
Referring again to
In the embodiment shown in
The oil passage 37A crosses over at ports 126 to another passage 37B which is formed in the upper section 128 of a transfer tube 130. The section 128 carries seal rings 131-133 to prevent fluid leakage, and the lower end of the passage 37B is connected to a length of small diameter patch tubing 134 which extends downward through an elongated annular cavity 57 formed between the outer wall of the transfer tube 130 and the inner wall of the chamber sub 106. The cavity 57 forms the low pressure dump chamber described above with reference to FIG. 2 and can have a relatively large volume, for example 150 cubic inches in the embodiment shown. The lower end of the patch tube 134 connects with a vertical passage 37C (
An elongated tube 140 is positioned concentrically within the sub 107 and arranged such that another elongated annular cavity 42 is formed between the outer wall surface of the tube and the inner wall surface of the sub. The cavity 42 forms the high pressure oil chamber shown schematically in FIG. 3 2, and also can have a volume in the neighborhood of 150 cubic inches. Outer seal rings 143-146 seal against the chamber sub 108 adjacent the ports 137, and inner seal rings 147 seal against the upper end section of the tube 140.
A hydrostatic pressure transfer piston 150 in the form of a ring member that carries inner and outer seals 156, 157 is slidably mounted within the annular chamber 42, and is located at the upper end thereof when the chamber is full of oil. The region 151 above the piston 150 is placed in communication with the well annulus outside the housing 100 by one or more radial ports 152. As shown in
As shown in
The pair of solenoid valves 65 and 76 that are operatively associated with the pilot valve 68 are mounted in transverse bores 190 and 205 in the wall of the sub 110 as shown in FIG. 7. The valve assembly 65 includes a sealed plug 191 that is threaded into the bore 190 as shown, the plug carrying an annular seat member 192 having a central port 193. The bore 194 of the plug 191 downstream of the port 193 is communicated by a passage 195 with an external annular groove 196 which is intersected by a passage 67′ in the valve sub 110, which, as shown, communicates with the passage 67 which leads to the pilot valve 68. 0-rings at appropriate locations, as shown, seal against fluid leakage. The seat member 192 cooperates with a valve element 197 on the end of a plunger 200 to prevent flow through the port 193 when the element is forced against the seat member, and to permit such flow when the element is in the open position away from the seat member as depicted in FIG. 7. The plunger 200 is biased toward the seat member 192 by a helical spring 202 that reacts against the base of a conical mount 203 which is threaded into the sub 110 at 204. A coil 205 that is fixed to the mount 203 surrounds the plunger 200 and, when energized by electric current, causes the plunger 200 and the valve electric 197 to back away from the seat member 192 to the open position. When the coil 205 is not energized, the spring 202 forces the plunger and valve element to advance to the closed position where a conical end surface of the element engaged a tapered seat surface on the member 192 to close the port 193. The passage 66, as shown in phantom lines, feeds into the bore 190 upstream of the seat ring 192, and the passage 67′ leads from the bore area adjacent the groove 196. The passage 66 leads upward in the housing 110 and into open communication with the high pressure chamber 42.
An identically constructed solenoid valve assembly 76 is mounted in a transverse bore 205 on the opposite side of the sub 110 from the assembly 65 as shown in
The other pair of solenoid valve assemblies 44 and 53 which are operatively associated with the pilot valve 50 are mounted in bores identical to the bores 190 and 205, but at a different axial level in the sub 110 as shown near the bottom of FIG. 5D. Being identically constructed, these assemblies also are not shown or described in detail to simplify this disclosure. The respective bores in which the assemblies 44 and 53 are mounted are intersected by the passages 43, 47 and 56, 47′, respectively, as described generally with reference to FIG. 2. Of course, appropriate electrical conductors lead to the respective coils of each of the solenoid valve assemblies 44, 53, 65, 76 through appropriately constructed bores, slots and high pressure feed-through connectors, (not shown) from the solenoid driver board 94 shown schematically in FIG. 3.
The cylinder passage 125 (
As shown in
As previously mentioned with reference to
If it is desirable to reclose the ports 102 so that other service work such as acidizing can be done in the well interval below the packer, another sequence of low level pressure pulses is applied at the surface to the annulus 13 via the line 18, which causes the controller 93 to signal the driver 94 to energize the solenoid valves 44 and 76, and to switch off the supply of current to the solenoid valves 53 and 65. When this occurs, the sleeve 220 and actuator 24 are shifted upward in response to high pressure acting on the lower face 34 of the piston 26, as previously described, to position the seal assembly 221 above the ports 102. The circulating valve 20 will remain closed until another command signal having a predetermined signature is applied to the annulus 13 to cause a downward movement of the mandrel 24.
An embodiment of the present invention where a valve element is employed to control flow of fluids through the central passageway 22 is shown in FIG. 8. Here, the upper end of the actuator mandrel 24 is provided with a pair of laterally offset, upstanding arms 225 that carry eccentric lugs 226 which engage in radial slots 227 in the outer side walls of a ball valve element 228. The ball valve 228 rotates about the axis of trunnions 230 on its opposite sides between an open position where the throughbore 231 of the ball element is axially aligned with the passageway 22, and a closed position where the spherical outer surface 232 thereof engages a companion seat 233 on the lower end of a seat sleeve 234. In the closed position, a composite seal ring assembly 235 prevents fluid leakage. On command as previously described, the mandrel 24 is moved upward and downward to correspondingly open and close the ball element 228. Positive feedback of the position of the ball element 228 is obtained at the surface through appropriate monitoring of pressure in the tubing 11. The use of a ball element 228 provides a valve structure that presents an unobstructed vertical passage through the tools in the open position, so that other well equipment such as string shot, perforating guns and pressure recorders can be lowered through the tool string on wireline. The ball element 228 also provides a large flow area in the open position, which is desirable when testing certain types of wells. The ball element 228 can function as the main test valve, a safety valve, or as a part of a sampler as will be apparent to those skilled in the art.
In operation, the valve and operating system is assembled as shown in the drawings, and the chamber 42 is filled with a suitable hydraulic oil until the floating piston 150 is at the upper end of the chamber as shown in FIG. 5C. The chamber 42 then can be pressurized somewhat to cause the shuttle 60 to open so that the lines 52, 51 and 38 are filled with oil, after which the solenoid valves 44 and 65 are temporarily opened to permit lines 43, 47 and 48, and the lines 66 and 67, to also fill with oil. The dump chamber 57 initially contains only air at atmospheric pressure. The actuator mandrel 24 is in its upper position where the circulating ports 102 are closed off by the mandrel section 220, and is held in such upper position by the return spring 32, if used as shown in FIG. 2. In the actuator embodiment shown in
At test depth the tool string is brought to a halt, and the packer 12 is set by appropriate pipe manipulation to isolate the well interval below it from the column of well fluids standing in the annulus 13 thereabove. To initiate a test, the main valve 14 is opened for a brief flow period to draw down the pressure in the isolated interval of the well bore, and then closed for a shut-in period of time during which fluid pressures are permitted to build up as formation fluids hopefully come into the borehole below the packer. The pressure recorders 16, 17 operate to provide chart recordings of pressure versus time elapsed during the test. If desired, suitable known instrumentalities can be used to provide a readout of data at the surface during the test.
To clear the pipe string 11 of formation fluids recovered during the test, the circulating valve 20 is opened in the following manner. A command signal constituted by a series of low level pressure pulses each having a specified duration is applied at the surface via the line 18 to the fluids standing in the well annulus 13. The pressure pulses are sensed by the transducer 95, whose output is coupled to the amplifier or receiver 92. The receiver 92 converts the low level electrical signals from the transducer 95 into an electrical signal having a certain format. The formatted signal is interrogatoried by the controller 93 to determine if electrical signals representing the command signal signature are present, or not. If such is the case, the controller 93 triggers operation of the solenoid driver 99 94, whereby selected pairs of the solenoid valves are supplied with current. Thus the actuator mandrel 24 is moved upward or downward on command from the surface. With pair 53, 65 energized, low pressure in the dump chamber 57 is communicated to the rear of the pilot valve shuttle 60, which causes it to shift open, whereby hydrostatic pressure of the oil in chamber 42 is applied to the upper face 40 of the actuator piston 26. Energization of the solenoid valve 65 ensures that pressures are balanced across the shuttle 70 so that its spring 74 retains it closed across the line 73. The difference between hydrostatic fluid pressure and atmospheric pressure thus is applied to the actuator piston 26 which produces downward force to drive the actuator mandrel 24 downward against the bias of the return spring 32. Such movement positions the valve seal assembly 221 below the side ports 102 in the housing 21 and after a suitable time delay to insure complete travel of the mandrel 24, the solenoid valves 53 and 65 are de-energized by the driver 94 in response to signals from the controller 93. Pressure then can be applied to the annulus 13 at the surface cause any fluids in the pipe string 11 to be reverse circulated to the surface where they can be piped to a suitable container for inspection and analysis, or disposed of if desired. If the test is to be terminated at this point, the packer 12 is unseated and the tool string withdrawn from the well so that the pressure recorder charts also can be inspected and analyzed
If further testing or other service work is to be done without removing the equipment from the well, the circulating valve 20 is reclosed. To accomplish this, another series of low level pressure pulses is applied at the surface to the fluids in the well annulus. Such pulses activate the controller 93 as described above, which causes the driver 94 to energize the other pair of solenoid valves 44, 76. Opening of the solenoid valve 44 equalizes pressures across the pilot valve shuttle 60, so that its spring 63 forces the shuttle closed across the line 51. The solenoid valve 53, when no longer energized, moves to its normally closed position against the seat 55. Opening of the solenoid valve 76 reduces the pressure on the spring side of the pilot shuttle 70, whereby pressure in the line 82 shifts the shuttle to open position where communication is established between line 82 and dump line 73. Of course the solenoid valve 65, when not energized, moves to its normally closed position. The return spring 32 forces the actuator mandrel 24 upward, displacing that volume of oil in the chamber region 36 into the dump chamber 57. By repeated applications of command signals to the fluids in the annulus 13, the circulating valve 20 can be repeatedly opened and closed.
Cycles of downward and upward movement of the actuator mandrel 24 also can be used to rotate the ball element 228 shown in
For purposes of this discussion, the well testing tool 11 of the preferred embodiment includes an electronics section, a first well tool control system connected to the electronics section, the test valve connected to the first well tool control system, a second well tool control system connected to the electronics section, and the reversing valve connected to the second well tool control system.
The solenoid driver board 94 is energized by a controller board 93. The controller board comprises a processor portion and a memory portion in which a set of microcode may be encoded. The controller board is powered by power supply board 91 and receives unique signature input signals from the command receiver board 92. The command receiver board 92 receives an input stimulus from a command sensor 95, which input stimulus may be an output signal from an annulus pressure transducer, a strain gauge or a bottom hole pressure transducer. The command sensor 95 may sense various types of input stimuli, such as changes in pressure within the annulus around the tool. The preferred embodiment will utilize changes in pressure within the annulus as the input stimulus to the command sensor 95, but only for purposes of illustration, since any type of input stimulus to command sensor 95 will suffice for purposes of the present invention. A first pressure change signal, having a first predetermined signature, transmitted into a borehole by an operator would be sensed by the command sensor 95 and interpreted by the controller board 93 as an intent to control the test valve 20, whereas a second pressure change signal, having a second predetermined signature, transmitted into the borehole by an operator, would be sensed by the command sensor 95 and interpreted by the controller board 93 as an intent to control the reversing valve 14.
The functional operation of the multiple well too tool control systems of the present invention is set forth in the following paragraphs with reference to
Each individual well tool control system, shown in FIG. 10 and
In operation, referring to
In operation, referring to
By incorporating suitable microcode into the controller board 93, the well tool control system of part B presented hereinabove may operate automatically, opening and closing various valves in the tool a predetermined number of times and in a predetermined sequence, in response to a single input kickoff stimulus. The input stimulus may, for example, be a sensing of a predetermined bottom hole pressure, in the borehole below the packer, and a generation of the proper input stimulus when the bottom hole pressure exceeds a predetermined level. When the input stimulus is generated, the pre-programmed series of instructions generated by the controller board 93 microcode may, for example, require that the well be flowed for 5 minutes, followed by a shut-in until stabilized pressure is reached, followed by flowing the well until the well appears to be killing itself, followed by shut-in until the Horner straight line is reached, followed by opening a reversing valve. The input stimulus may also be a sensing of a specific set down weight of the tool in the borehole when the tool reaches bottom, via a strain gauge placed on the tool, and a generation of an input stimulus when the set down weight reaches a predetermined amount. In response to the input stimulus representative of the specific set down weight of the tool, a specific action would be taken, such as opening a test valve for 5 minutes, then closing the valve for 1 hour, then opening the valve for 1 hour, then closing the valve for 2 hours, after which a reversing valve would open.
The exact sequence of valve openings and closings, and the exact number of times the valves are opened and closed per hour, is determined by the specific instructions encoded into the controller board memory chip. A flow chart of the microcode instructions is presented hereinbelow.
The invention of this application is a system which includes a processor portion (e.g., the Intel 8088 microprocessor) and a memory portion (ROM 93b), the memory storing certain instructions therein. When the instructions stored in the memory portion are executed by the processor portion, certain specific functions are performed by the system. In
The following is a description of the automode 1 test.
If automode 1 is set, a series of questions are asked by the ROM microcode (block b8): “is it time for first shut-in?; is it time for second shut-in?; is it time for first flow or second flow?; is it time for reverse?”; referring also to
If automode 1 is not set, the ROM microcode asks “is automode 2 set?” (block b12). Automode 2 is a test whose sequence is automatically controlled based on a combination of time and measured bottom hole pressure. For example, if the measured bottom hole pressure falls on a certain curve (Horner straight line) or value, the processor 93a opens and/or closes the test valve and/or the reversing valve; otherwise, if the bottom hole pressure does not fall on such curve or value, the test valves and/or reversing valves are opened and/or closed in accordance with a predetermined elapsed time.
The following is a description of the automode 2 test.
The first question asked by the ROM microcode is: “what is the test type, impulse or conventional?” (block b13). An impulse test is a 1 flow test whereas a conventional test is a 2 flow test. If the test is the impulse type: open the test valve (block b14); ask “is the well killing itself?” (is the hydrostatic head pressure the=formation pressure?) (block b15); if yes, close the test valve (block b16), if no, ask “is the flow time exceeded (T is greater than or equal to T1)?” (block b17); if no, return to the top of block b3, if yes, close the test valve (block b16), then ask “is the Horner straight line reached?” (has the bottom hole pressure reached a predetermined criterion, the criterion in this case being the Horner straight line?) (block b18); if yes, open the reversing valve (block b19), if no, ask “is shut-in time exceeded (T greater than or equal to time T2)?” (block b20); if no, return to the top of the block b3, if yes, open the reversing valve (block b19) and return to the top of block b3, which asks “is override received?”. If the test is the conventional type: open the test valve (block b21), and ask “is the well killing itself?” (block b22); if yes, close the test valve (block b23) and return to the top of block b3, if no, ask “is it time for shut-in (is T less than T1 or is T greater than or equal to T1)?” (block b24); if T is less than T1, it is not time for shut-in and return to the top of block b3; if T is greater than or equal to time T1, it is time for shut-in and close the test valve (block b25); ask “has the bottom hole pressure (BHP or Pbh) stabilized (i.e., is the current bottom hole pressure the previous bottom hole pressure)?” (bottom b26); if yes, open the test valve (block b27), if no, ask “is shut-in time exceeded (is T greater than or equal to T2)?” (block b28), if no, return to the top of block b3, if yes, open the test valve (block b27); the ROM microcode, as executed by the processor, asks “is the well killing itself?” (block b29), if yes, shut the test valve (block b30), if no, ask “is flow time exceeded (T greater than or equal to time T3?” (block b31); if no, return to top of block b3, if yes, shut the test valve (block b30); the ROM microcode (as interrogated by the processor portion) asks “is the Horner straight line reached?” (block b32), if yes, open the reversing valve (block b33) and return to the top of block b3, if no, ask “is shut-in time exceeded (is T greater than or equal to time T4)?” (block b34); if yes, open the reversing valve (block b33) and return to the top of block b3, if no, return to the top of block b3.
In the above functional and structural description of the ROM microcode, where the question is asked “is the Horner straight line reached” other criteria could be used, such as Log-Log straight line, or type curve matching. Where the question is asked “is the well killing itself”, other criteria could be used or a feedback from a downhole flowmeter could be used to control the flowrate (e.g., constant Q) through a downhole variable choke. Blocks b10 and b33 are optional; reversing could be controlled only by override. In block b8, this is a preprogrammed test where T1, T2, T3, T4 are preset. In block b13, for the conventional test, the times T1-T4 maximums are preset; for the impulse test, the times T1, T2 maximums are preset.
The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.
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|U.S. Classification||166/250.15, 166/64, 166/66.7, 166/264, 166/53, 166/66.6, 166/374|
|International Classification||E21B34/10, E21B23/04, E21B47/18, E21B34/16, E21B34/00, E21B34/06, E21B41/00, E21B34/08, E21B49/04|
|Cooperative Classification||E21B23/04, E21B47/18, E21B34/06, E21B41/00, E21B34/16, E21B34/10, E21B2034/002|