CN202913991U - Down-hole high-frequency pressure pulse generation device - Google Patents
Down-hole high-frequency pressure pulse generation device Download PDFInfo
- Publication number
- CN202913991U CN202913991U CN201220562171.XU CN201220562171U CN202913991U CN 202913991 U CN202913991 U CN 202913991U CN 201220562171 U CN201220562171 U CN 201220562171U CN 202913991 U CN202913991 U CN 202913991U
- Authority
- CN
- China
- Prior art keywords
- drilling tool
- pressure pulse
- transmission shaft
- generator shell
- frequency pressure
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Images
Landscapes
- Connection Of Motors, Electrical Generators, Mechanical Devices, And The Like (AREA)
Abstract
The utility model discloses a down-hole high-frequency pressure pulse generation device. The down-hole high-frequency pressure pulse generation device comprises a generator shell (1) and a drill short section (2). A connecting shaft (6) and a transmission shaft (13) are sequentially arranged inside the generator shell (1), and a power drilling tool rotor (10) and a power drilling tool stator (11) are arranged between the transmission shaft (13) and the generator shell (1), wherein the power drilling tool rotor (10) and the power drilling tool stator (11) are adaptive mutually. A flange plate (131) is arranged at one end of the transmission shaft (13), a throttling plate (14) is arranged close to the flange plate (131), the flange plate (131) is provided with a water hole (132), and the throttling plate (14) is provided with a water groove (141). By exerting high-frequency pressure pulses on a drill position, shaft bottom environment can be improved, a cutting bringing ability of drilling fluid is improved, hold-down effect of the drilling fluid is reduced effectively, drilling speed is increased, and an existing drilling device can not achieve the effect.
Description
Technical field
The utility model relates to the oil and gas well drilling technical field, particularly a kind of down-hole high-frequency pressure pulse generating unit.
Background technology
Along with the development of geological prospecting and drilling technology and drilling technology is required more and more higher, also more and more higher to the requirement of drilling equipment.In recent years, China has strengthened the dynamics to the deep formation exploration, and the deep drilling quantity in western part, the Sichuan Basin and surrounding area increases year by year.Under normal drilling condition, the PDC drill bit can drill the stratum with high speed and efficient.But the PDC drill bit can reduce cutting depth in hard, fixed rock stratum.This means that also the PDC cutting knife must rely on the grinding stratum to creep into, rather than shears the stratum, and this will reduce drilling speed (ROP), greatly increases the blade abrasion degree.Simultaneously, because the increase of well depth, drilling fluid is more obvious for the chip hold down effect on stratum, has increased the difficulty of drilling well.Along with oil/gas drilling develops to the deep, the difficult problem that hard formation creeps into becomes increasingly conspicuous, and how to change this situation and becomes drilling speed problem in the urgent need to address.
In realizing process of the present utility model, the inventor finds that there is following problem at least in prior art: by apply the pressure pulse of high frequency at the drill bit place, can improve downhole environment, improve Improving Mud Carrying Capacity, effectively alleviate the chip hold down effect of drilling fluid, improve bit speed, and existing drilling equipment can't reach these effects.
The utility model content
In order to solve the problem of prior art, the utility model embodiment provides a kind of down-hole high-frequency pressure pulse generating unit, this device is by applying the pressure pulse of high frequency at the drill bit place, can improve downhole environment, improve Improving Mud Carrying Capacity, effectively alleviate the chip hold down effect of drilling fluid, improve bit speed.Simultaneously, the high-frequency pressure pulse that this device produces has auxiliary rock-breaking effect, can reduce the stick-slip phenomenon of drill bit in the drilling process, improves bit life.Described technical scheme is as follows:
A kind of down-hole high-frequency pressure pulse generating unit is provided, and described device comprises: generator shell and drill bit pup joint, described generator shell are hollow structure, and described generator shell is fixedly connected with described drill bit pup joint; Described generator shell inside is disposed with connecting axle and power transmission shaft, the first end of described power transmission shaft is connected with described connecting axle, the second end of described power transmission shaft is arranged in the described drill bit pup joint, be provided with mutually adaptive power drilling tool rotor and power drilling tool stator between the periphery of described power transmission shaft and the inwall of described generator shell, the second end of described power transmission shaft is provided with flange, is right after described flange and is provided with throttling plate; Evenly offer a plurality of hydrophthalmias on the described flange, evenly offer a plurality of tanks on the described throttling plate, radially during relative the rotation, have the described hydrophthalmia of predetermined quantity to overlap fully with the described tank of equal number at described power transmission shaft and described throttling plate.
Further, evenly offer six hydrophthalmias on the described flange, evenly offer three tanks on the described throttling plate, radially during relative the rotation, have at least three described hydrophthalmias to overlap fully with three described tanks at described power transmission shaft and described throttling plate.
Further, be provided with the suspension block plate between the periphery of described connecting axle and the inwall of described generator shell, described suspension block plate is fixed on the described generator shell; The upper end of described connecting axle is passed the center hole of described suspension block plate and is fixed on the described suspension block plate by anti-lost nut.
Further, in the center hole of described suspension block plate abrasion-resistant slide bearing being installed, is interference fit between described abrasion-resistant slide bearing and the described suspension block plate, is matched in clearance between described connecting axle and the described abrasion-resistant slide bearing.
Further, described power drilling tool rotor is fixed on the periphery of described power transmission shaft, described power drilling tool stator is fixed on the inwall of described generator shell, and described power drilling tool rotor and described power drilling tool stator have mutually adaptive many groups turbine or screw rod.
Further, be provided with anti-lost ring between described power drilling tool stator and the described suspension block plate, the upper surface of described anti-lost ring leans the soffit setting of described suspension block plate, and the lower end of described anti-lost ring and described power drilling tool stator are equipped with by step.
Further, the inside of described drill bit pup joint is provided with installation step, and described throttling plate is installed in the described drill bit pup joint by described installation step.
Further, be processed with the bearing torque face on the periphery wall of described throttling plate, be provided with accordingly suitable bearing torque face on the internal face of described drill bit pup joint, described throttling plate cooperates by the bearing torque face with described drill bit pup joint realizes radial location.
Further, offer the perforation hole on the described suspension block plate, offer the perforation slotted eye on described power drilling tool rotor and the described power drilling tool stator, described perforation hole, described perforation slotted eye, described hydrophthalmia and described tank connect described device in described generator shell.
The beneficial effect that the technical scheme that the utility model embodiment provides is brought is:
Down-hole of the present utility model high-frequency pressure pulse generating unit can improve downhole environment by apply the pressure pulse of high frequency at the drill bit place, improves Improving Mud Carrying Capacity, effectively alleviates the chip hold down effect of drilling fluid, improves bit speed.On the other hand, this device improves downhole environment by the pressure pulse that produces in drilling process, improves efficiency of breaking rock, minimizing drill bit stick-slip, the prolongation bit life of firm hard formation.
Description of drawings
In order to be illustrated more clearly in the technical scheme among the utility model embodiment, the accompanying drawing of required use was done to introduce simply during the below will describe embodiment, apparently, accompanying drawing in the following describes only is embodiment more of the present utility model, for those of ordinary skills, under the prerequisite of not paying creative work, can also obtain according to these accompanying drawings other accompanying drawing.
Fig. 1 is the down-hole high-frequency pressure pulse generating unit structural representation that the utility model embodiment provides;
Fig. 2 is the enlarged drawing schematic diagram at R place among Fig. 1;
Fig. 3-Fig. 4 be when power transmission shaft turns an angle in the device among Fig. 1 A-A to sectional drawing;
Fig. 5 be among Fig. 1 B-B to sectional drawing.
The specific embodiment
For making the purpose of this utility model, technical scheme and advantage clearer, below in conjunction with accompanying drawing the utility model embodiment is described in further detail.
Embodiment
Present embodiment provides a kind of down-hole high-frequency pressure pulse generating unit, referring to Fig. 1, this down-hole high-frequency pressure pulse generating unit comprises: generator shell 1 and drill bit pup joint 2, this generator shell 1 is hollow structure, and the hollow of generator shell 1 is inner to be used for other component of high-frequency pressure pulse generating unit under the mounting shaft.The first end of this generator shell 1 has jointing, is used for being connected with external equipment; The second end of this generator shell 1 is provided with internal thread, generator shell 1 is fixedly connected with drill bit pup joint 2 at the second end, accordingly, the link of drill bit pup joint 2 is provided with external screw thread, and generator shell 1 interconnects by the internal and external threads that is arranged on them with drill bit pup joint 2.
Continuation is referring to Fig. 1, and generator shell 1 inside is disposed with connecting axle 6 and power transmission shaft 13, and connecting axle 6 is arranged on the upper end, and power transmission shaft 13 is arranged on the lower end.The first end of power transmission shaft 13 is connected with connecting axle 6, particularly, the first end of power transmission shaft 13 offers installs the hole, be provided with internal thread on the inside peripheral wall in this installation hole, the respective ends of connecting axle 6 is provided with external screw thread, the respective ends of connecting axle 6 extend in the installation hole of power transmission shaft 13, and connects by internal and external threads.The second end of power transmission shaft 13 is arranged in the drill bit pup joint 2, the second end of power transmission shaft 13 is provided with flange 131, the external diameter size of this flange 131 is roughly the same with the internal diameter size that drill bit pup joint 2 should be located, and flange 131 can be made radial rotary with respect to drill bit pup joint 2.
In conjunction with referring to Fig. 2, be right after flange 131 and be provided with throttling plate 14, namely throttling plate 14 is arranged in the drill bit pup joint 2, and the upper surface of throttling plate 14 is near the lower surface setting of flange 13.On flange 131, evenly offer a plurality of hydrophthalmias 132, on throttling plate 14, evenly offer a plurality of tanks 141, radially during relative the rotation, have the hydrophthalmia 132 of predetermined quantity to overlap fully with the tank 141 of equal number at power transmission shaft 13 and throttling plate 14.Preferably, be provided with installation step 21 in the inside of drill bit pup joint 2, throttling plate 14 is installed in the drill bit pup joint 2 by this installation step 21, and throttling plate 14 is fixedly connected with drill bit pup joint 2, and throttling plate 14 is with drill bit pup joint 2 synchronous rotaries.More preferably, be processed with the bearing torque face at the periphery wall of throttling plate 14, be provided with accordingly suitable bearing torque face on the internal face of drill bit pup joint 2, throttling plate 14 cooperates by the bearing torque face with drill bit pup joint 2 realizes radial location.
As preferred embodiment, in conjunction with referring to Fig. 3 and Fig. 4, evenly offer six hydrophthalmias 132 on the flange 131, the shape of cross section that hydrophthalmia 132 is is for circular, evenly offer three tanks 141 on the throttling plate 14, the shape of cross section of tank 141 is that semi arch, both sides are the deep-slotted chip breaker that camber line forms by two ends, radially during relative the rotation, has at least three hydrophthalmias 132 to overlap fully with three tanks 141 at power transmission shaft 13 and throttling plate 14.
Be provided with mutually adaptive power drilling tool rotor 10 and power drilling tool stator 11 between the inwall of the periphery of power transmission shaft 13 and generator shell 1, power drilling tool stator 11 is fixed on by set bolt 12 on the inwall of generator shell 1, and power drilling tool rotor 10 is fixed on the periphery of power transmission shaft 13.Particularly, the inside of power drilling tool rotor 10 is hollow form, and the inside of this hollow is provided with internal thread, is provided with external screw thread at the corresponding site of power transmission shaft 13, and power drilling tool rotor 10 and power transmission shaft 13 are fixedly connected with by internal and external threads.Preferably, be provided with step in the upper end of power drilling tool rotor 10, this step of power drilling tool rotor 10 is mounted in the connection junction that power transmission shaft 13 is connected with connecting axle, and this step carries out axial location to power drilling tool rotor 10.
Continuation is provided with between the periphery of connecting axle 6 upper ends and the inwall of generator shell 1 and hangs block plate 3 referring to Fig. 1, and this suspension block plate 3 is bolted on generator shell 1.The upper end of connecting axle 6 is passed the center hole of suspension block plate 3 and is fixed on the suspension block plate 3 by anti-lost nut 7.Preferably, in the center hole that hangs block plate 3, abrasion-resistant slide bearing 8 is installed, is inlaid with carbide alloy on the inwall of abrasion-resistant slide bearing 8.Be interference fit between this abrasion-resistant slide bearing 8 and the suspension block plate 3, be matched in clearance between connecting axle 6 and the abrasion-resistant slide bearing 8, like this, connecting axle 6 can and hang block plate 3 and make radial rotary with respect to abrasion-resistant slide bearing 8, and abrasion-resistant slide bearing 8 and suspension block plate 3 are with respect to generator shell 1 transfixion.
Preferably, power drilling tool rotor 10 and power drilling tool stator 11 have mutually adaptive many groups turbine, and power drilling tool rotor 10 and power drilling tool stator 11 consist of the power drilling tool of this down-hole high-frequency pressure pulse generating unit.As other embodiment, the power drilling tool of this down-hole high-frequency pressure pulse generating unit can be a screw rod.At power drilling tool stator 11 and hang between the block plate 3 and be provided with anti-lost ring 5, the upper surface of anti-lost ring 5 leans the soffit setting of hanging block plate 3, and the lower end of anti-lost ring 5 and power drilling tool stator 11 are equipped with by step.
Preferably, offer perforation hole 9 at suspension block plate 3, offer perforation slotted eye 101 at power drilling tool rotor 10 and power drilling tool stator 11, connect hole 9, connect slotted eye 101, hydrophthalmia 132 and tank 141 at this down-hole high-frequency pressure pulse generating unit of generator shell 1 interior perforation.
This device is installed on the drill bit and uses, and the pressure pulse of generation can arrive the shaft bottom by effective communication, and attenuation amplitude is little; This apparatus structure is compact, does not contain any rubber parts and electronic devices and components, can be high temperature resistant 210 °; Through practical proof, it is high that this device produces the pressure pulse frequency, is six times of power drilling tool rotating speed; Pressure pulse amplitude adjustable extent is large, by changing power transmission shaft hydrophthalmia size, can realize the adjusting in pressure pulse 0.1～2MPa scope.
The operating principle of this down-hole high-frequency pressure pulse generating unit is:
During work, generator shell 1 top of this down-hole high-frequency pressure pulse generating unit connects normal drilling assembly, and the bottom of drill bit pup joint 2 connects drill bit.Drilling fluid enters the centre bore of generator shell 1 via the top drilling tool water hole, flows downward through uniform drilling fluid passage around hanging block plate 3 again, arrives power drilling tool, i.e. power drilling tool rotor 10 and power drilling tool stator 11 places.Drive the power drilling tool rotor during drilling fluid process power drilling tool, thereby drive power transmission shaft 13 rotations, wherein, the rotating speed size depends on discharge capacity and the density of drilling fluid.In power transmission shaft 13 rotary courses, on its underpart flange 131 uniform six hydrophthalmias 132 periodic with throttling plate 14 on uniform three tanks 141 occur to overlap fully, bottom pressure is the highest at this moment; Minimum in the rotary course can have three hydrophthalmias 132 to overlap fully with three tanks 141, and this moment, bottom pressure was minimum.In 13 every one weeks of rotation of power transmission shaft, six hydrophthalmias 132 will occur six times with three tanks 141 and overlap fully, produce six pressure oscillations.Therefore, the frequency of pressure pulse is six times of rotating speed.When 60 ° of every rotations of power transmission shaft, the process of a pressure oscillation occurs.This device also can pass through to change the amplitude that the hydrophthalmia size changes pressure pulse, and by the quantity of adjustment hydrophthalmia and tank and the frequency of position change pressure pulse, and adjustable range is wide.
The above only is preferred embodiment of the present utility model, and is in order to limit the utility model, not all within spirit of the present utility model and principle, any modification of doing, is equal to replacement, improvement etc., all should be included within the protection domain of the present utility model.
Claims (9)
1. down-hole high-frequency pressure pulse generating unit, it is characterized in that, described device comprises: generator shell (1) and drill bit pup joint (2), and described generator shell (1) is hollow structure, described generator shell (1) is fixedly connected with described drill bit pup joint (2);
Described generator shell (1) inside is disposed with connecting axle (6) and power transmission shaft (13), the first end of described power transmission shaft (13) is connected with described connecting axle (6), the second end of described power transmission shaft (13) is arranged in the described drill bit pup joint (2), be provided with mutually adaptive power drilling tool rotor (10) and power drilling tool stator (11) between the inwall of the periphery of described power transmission shaft (13) and described generator shell (1), the second end of described power transmission shaft (13) is provided with flange (131), is right after described flange (131) and is provided with throttling plate (14);
Evenly offer a plurality of hydrophthalmias (132) on the described flange (131), evenly offer a plurality of tanks (141) on the described throttling plate (14), radially during relative the rotation, there is the described hydrophthalmia (132) of predetermined quantity to overlap fully with the described tank (141) of equal number at described power transmission shaft (13) and described throttling plate (14).
2. down-hole according to claim 1 high-frequency pressure pulse generating unit, it is characterized in that, evenly offer six hydrophthalmias (132) on the described flange (131), evenly offer three tanks (141) on the described throttling plate (14), radially during relative the rotation, have at least three described hydrophthalmias (132) to overlap fully with three described tanks (141) at described power transmission shaft (13) and described throttling plate (14).
3. down-hole according to claim 1 high-frequency pressure pulse generating unit, it is characterized in that, be provided with between the inwall of the periphery of described connecting axle (6) and described generator shell (1) and hang block plate (3), described suspension block plate (3) is fixed on the described generator shell (1);
The upper end of described connecting axle (6) is passed the center hole of described suspension block plate (3) and is fixed on the described suspension block plate (3) by anti-lost nut (7).
4. down-hole according to claim 3 high-frequency pressure pulse generating unit, it is characterized in that, abrasion-resistant slide bearing (8) is installed in the center hole of described suspension block plate (3), being interference fit between described abrasion-resistant slide bearing (8) and the described suspension block plate (3), is matched in clearance between described connecting axle (6) and the described abrasion-resistant slide bearing (8).
5. down-hole according to claim 1 high-frequency pressure pulse generating unit, it is characterized in that, described power drilling tool rotor (10) is fixed on the periphery of described power transmission shaft (13), described power drilling tool stator (11) is fixed on the inwall of described generator shell (1), and described power drilling tool rotor (10) and described power drilling tool stator (11) have mutually adaptive many groups turbine or screw rod.
6. down-hole according to claim 5 high-frequency pressure pulse generating unit, it is characterized in that, be provided with anti-lost ring (5) between described power drilling tool stator (11) and the described suspension block plate (3), the upper surface of described anti-lost ring (5) leans the soffit setting of described suspension block plate (3), and the lower end of described anti-lost ring (5) and described power drilling tool stator (11) are equipped with by step.
7. down-hole according to claim 1 high-frequency pressure pulse generating unit, it is characterized in that, the inside of described drill bit pup joint (2) is provided with installation step (21), and described throttling plate (14) is installed in the described drill bit pup joint (2) by described installation step (21).
8. down-hole according to claim 7 high-frequency pressure pulse generating unit, it is characterized in that, be processed with the bearing torque face on the periphery wall of described throttling plate (14), be provided with accordingly suitable bearing torque face on the internal face of described drill bit pup joint (2), described throttling plate (14) cooperates by the bearing torque face with described drill bit pup joint (2) realizes radial location.
9. according to claim 4,6 or 8 described down-hole high-frequency pressure pulse generating units, it is characterized in that, offer on the described suspension block plate (3) and connect hole (9), offer on described power drilling tool rotor (10) and the described power drilling tool stator (11) and connect slotted eye (101), described perforation hole (9), described perforation slotted eye (101), described hydrophthalmia (132) and described tank (141) connect described device in described generator shell (1).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201220562171.XU CN202913991U (en) | 2012-10-30 | 2012-10-30 | Down-hole high-frequency pressure pulse generation device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201220562171.XU CN202913991U (en) | 2012-10-30 | 2012-10-30 | Down-hole high-frequency pressure pulse generation device |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN202913991U true CN202913991U (en) | 2013-05-01 |
Family
ID=48162312
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201220562171.XU Expired - Fee Related CN202913991U (en) | 2012-10-30 | 2012-10-30 | Down-hole high-frequency pressure pulse generation device |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN202913991U (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103790527A (en) * | 2012-10-30 | 2014-05-14 | 中国石油天然气集团公司 | Underground high-frequency pressure pulse generator |
| CN112303068A (en) * | 2020-09-24 | 2021-02-02 | 青岛***通科技有限公司 | Device and method for outputting high-frequency pressure pulse |
| CN113027329A (en) * | 2021-04-30 | 2021-06-25 | 四川天源宏创科技有限公司 | Torque pulse and pressure pulse double-acting tool |
-
2012
- 2012-10-30 CN CN201220562171.XU patent/CN202913991U/en not_active Expired - Fee Related
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103790527A (en) * | 2012-10-30 | 2014-05-14 | 中国石油天然气集团公司 | Underground high-frequency pressure pulse generator |
| CN103790527B (en) * | 2012-10-30 | 2017-02-08 | 中国石油天然气集团公司 | Underground high-frequency pressure pulse generator |
| CN112303068A (en) * | 2020-09-24 | 2021-02-02 | 青岛***通科技有限公司 | Device and method for outputting high-frequency pressure pulse |
| CN112303068B (en) * | 2020-09-24 | 2023-09-05 | 青岛***通科技有限公司 | Device and method for outputting high-frequency pressure pulse |
| CN113027329A (en) * | 2021-04-30 | 2021-06-25 | 四川天源宏创科技有限公司 | Torque pulse and pressure pulse double-acting tool |
| CN113027329B (en) * | 2021-04-30 | 2023-07-14 | 四川天源宏创科技有限公司 | Double-acting tool for torque pulse and pressure pulse |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN104405287B (en) | A kind of drilling well dipulse hydroscillator | |
| CN103790527A (en) | Underground high-frequency pressure pulse generator | |
| CN102747958B (en) | Compound vibrating well-drilling tool | |
| CN204139968U (en) | A kind of drilling well dipulse hydroscillator | |
| WO2016150113A1 (en) | Positive displacement motor drill and rock breaking well drilling method therefor | |
| CN102777122B (en) | Impact screw drilling tool | |
| CN208534403U (en) | A kind of horizontal well impulse hunting drill feeding facility | |
| CN106121513A (en) | A kind of composite impact drilling tool | |
| CN202731752U (en) | Composite vibration drilling tool | |
| CN202745686U (en) | Impact screw drilling tool | |
| CN202913991U (en) | Down-hole high-frequency pressure pulse generation device | |
| CN103696763A (en) | Continuous wave generator rotary valve based on triangular valve body | |
| CN203614029U (en) | Turbine torsional impact generator | |
| CN106499340B (en) | A kind of fluid power pulse generating unit and its operating method | |
| CN202689935U (en) | Hydraulic vibrator for drilling | |
| CN206129207U (en) | Novel oscillatory surge ware based on turbine and cam | |
| CN103670269B (en) | Turbine torsional impact generator | |
| CN102758588B (en) | Vibrator for coaxial type audio frequency physical exploring drill | |
| CN204326969U (en) | Method of longitudinal vibration of drilling string is converted into the device of drill bit torsional pulse | |
| CN203035438U (en) | Shaft bottom engine | |
| CN109611028A (en) | Hydroscillator based on roller and impeller | |
| CN102926654B (en) | Stake holes ring cutting system and stake holes ring cutting method | |
| CN208330181U (en) | A kind of downhole tool rotating device | |
| CN205225090U (en) | A buffering short circuit for reducing drilling string vibration damage | |
| CN202073498U (en) | Chambering type pressure-reduction acceleration drill bit |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20130501 Termination date: 20211030 |
|
| CF01 | Termination of patent right due to non-payment of annual fee |