EP0870900A1 - Verfahren und Gerät zur Bohrlochüberwachung - Google Patents
Verfahren und Gerät zur Bohrlochüberwachung Download PDFInfo
- Publication number
- EP0870900A1 EP0870900A1 EP97201092A EP97201092A EP0870900A1 EP 0870900 A1 EP0870900 A1 EP 0870900A1 EP 97201092 A EP97201092 A EP 97201092A EP 97201092 A EP97201092 A EP 97201092A EP 0870900 A1 EP0870900 A1 EP 0870900A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- chamber
- wellbore
- fluid
- sensors
- well
- 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.)
- Withdrawn
Links
- 238000000034 method Methods 0.000 title claims abstract description 23
- 238000012544 monitoring process Methods 0.000 title claims abstract description 15
- 239000012530 fluid Substances 0.000 claims abstract description 64
- 230000015572 biosynthetic process Effects 0.000 claims abstract description 37
- 238000004519 manufacturing process Methods 0.000 claims abstract description 26
- 239000011148 porous material Substances 0.000 claims abstract description 18
- 238000004891 communication Methods 0.000 claims abstract description 6
- 239000003921 oil Substances 0.000 claims description 31
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 30
- 239000007789 gas Substances 0.000 claims description 21
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 claims description 19
- 239000003345 natural gas Substances 0.000 claims description 7
- 239000010779 crude oil Substances 0.000 claims description 6
- 239000004568 cement Substances 0.000 claims description 3
- 239000003990 capacitor Substances 0.000 abstract description 7
- 238000005755 formation reaction Methods 0.000 description 31
- 238000012806 monitoring device Methods 0.000 description 23
- 238000005259 measurement Methods 0.000 description 4
- 230000001939 inductive effect Effects 0.000 description 3
- 238000013507 mapping Methods 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 238000002347 injection Methods 0.000 description 2
- 239000007924 injection Substances 0.000 description 2
- 238000009434 installation Methods 0.000 description 2
- 238000012546 transfer Methods 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000003384 imaging method Methods 0.000 description 1
- 238000011065 in-situ storage Methods 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 230000008054 signal transmission Effects 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
Images
Classifications
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B49/00—Testing the nature of borehole walls; Formation testing; Methods or apparatus for obtaining samples of soil or well fluids, specially adapted to earth drilling or wells
- E21B49/08—Obtaining fluid samples or testing fluids, in boreholes or wells
- E21B49/087—Well testing, e.g. testing for reservoir productivity or formation parameters
- E21B49/088—Well testing, e.g. testing for reservoir productivity or formation parameters combined with sampling
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B47/00—Survey of boreholes or wells
- E21B47/04—Measuring depth or liquid level
- E21B47/047—Liquid level
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B47/00—Survey of boreholes or wells
- E21B47/10—Locating fluid leaks, intrusions or movements
- E21B47/113—Locating fluid leaks, intrusions or movements using electrical indications; using light radiations
Definitions
- the invention relates to a method and device for downhole monitoring of physical characteristics of fluids.
- the invention relates to a method and device for monitoring physical characteristics of fluids in the pore spaces of an underground formation surrounding a wellbore.
- Fluid composition monitoring is useful in reservoir formations where water or gas coning occurs around the well or wells through which crude oil is produced. In such reservoir formations it is therefore particularly relevant to continuously monitor the location(s) of the oil, gas and/or water interfaces at a variety of downhole locations.
- US patent specification No. 2,564,198 discloses a method wherein the inflow section of producing well is divided into a number of subsections by a removable well testing apparatus, which is equipped with a series of expandable packers.
- composition of the fluid that flows into each subsection is monitored by a fluid identifier unit which may measure the electrical conductivity of the produced fluid.
- US patent specification No. 5,132,903 discloses a method wherein a removable measuring sonde is lowered into the inflow region of an oil production well and a pad can be forced against the borehole wall to provide a sealed chamber from which fluid is evacuated by a pump and the properties of the thus withdrawn pore fluid(s) are measured.
- This known method allows determination of the oil/water concentrations on the basis of a measurement of the dielectric properties of the produced fluids.
- Other dielectric well logging devices are disclosed in US patent specifications Nos. 2,973,477 and 4,677,386, German patent specification 2621142 and European patent specification 0111353.
- a disadvantage of the known monitoring techniques is that use is made of measuring equipment which is temporarily lowered into the wells to perform the measurements and that these methods primarily measure characteristics of fluids that are flowing into the well.
- An object of the present invention is to provide a method and device which enable a continuous downhole measurement of in-situ characteristics of the fluids in the pore spaces of the formation surrounding the wellbore.
- Further objects of the present invention are to provide a downhole fluid monitoring method which can be carried out by means of a measuring device which can be easily installed at any location within a wellbore in such a way that it does not obstruct access to and/or production from lower parts of the well and which can be easily removed or replaced.
- the method according to the invention comprises creating in the wellbore a measuring chamber which is in fluid communication with the pore spaces of the formation but which is hydraulically isolated from the rest of the wellbore, thereby creating a body of substantially stagnant fluid in the chamber and measuring physical characteristics of the fluid in the chamber by means of a number of sensors that are mounted within the chamber.
- the sensors are capacitive sensors which are suitable for detecting the presence of water, crude oil and/or natural gas in the region of the sensor and that a string of sensors is arranged in the chamber which sensors are axially spaced with respect to a longitudinal axis of the wellbore and which sensors are connected to fluid level monitoring equipment which is adapted to identify the presence and location of an interface between different fluids, such as water, crude oil and/or natural gas in the region of the string of sensors.
- the measuring chamber is an annular chamber which is isolated from the rest of the wellbore by means of a fluid tight sleeve and a pair of axially spaced packers that are arranged between the sleeve and an inner surface of the wellbore.
- the fluid monitoring device comprises a sleeve for creating in the wellbore measuring chamber which, when in use, is in fluid communication with the pore spaces of the formation but which is hydraulically isolated by the sleeve and packers mounted on the sleeve from the rest of the wellbore thereby creating a body of substantially stagnant fluid in the chamber, and a number of sensors that are mounted within the chamber for measuring physical characteristics of the fluid inside the chamber.
- Fig. 1 there is shown a production well 1 via which natural gas (referred to as CH 4 in the drawings) is produced.
- CH 4 natural gas
- H 2 O cone 2 of water
- a downhole monitoring device 4 is installed in the well 1.
- the monitoring device comprises a tubular sleeve 5 which is equipped with a pair of packers 6.
- the packers are expanded once the sleeve 5 has been lowered to the location where the measurements are to be made to seal off the upper and lower ends of the annular space between the sleeve 5 and a well casing 7, thereby forming an annular measuring chamber 8 which is hydraulically isolated from the rest of the wellbore.
- the well casing 7 Before installation of the device 4 the well casing 7 has been provided with perforations 9 via which the fluid in the pores of the reservoir formation 3 surrounding the device 4 is given free access to the measuring chamber 8.
- the fluid in the chamber 8 is substantially stagnant and an equilibrium is established between the gas/water (CH 4 /H 2 O) interface 10 in the measuring chamber 8 and the gas/water interface in the surrounding reservoir formation 3.
- the gas/water or other fluid interface in the reservoir formation 3 surrounding the well 1 can be monitored from inside of the measuring chamber 8 using an array of capacitor sensors 11 that are embedded in, or mounted on, the outer surface of the sleeve 5.
- Fig. 3 shows at a further enlarged scale the array of capacitor sensors 11 and illustrates the variation of dielectric constants measured at the gas/water interface 10. Since the dielectric constant of water is about 80 times larger than the dielectric constant of natural gas a high resolution of the device as an interface monitor is possible.
- Capacitor sensors 11 are known in the art and are being used for interface detection in e.g. storage tanks and will therefore not be described in detail. The use of capacitor sensors 11 requires simple, non-sensitive electronics downhole and needs but low electrical power.
- the vertical resolution that can be achieved with this type of sensors is in the order of a few mm.
- the data transfer from and power supply to the monitoring device 4 is performed by an inductive coupler 12 installed on a production or other tubing 13 at a location adjacent to the device 4.
- the inductive coupler 12 is connected to surface electronics (not shown) through an electrical cable 14.
- the production tubing 13 can be used to install the inductive coupler 12 and to clamp on the electrical cable 14. If the device 4 is to be installed below the lowermost casing-tubing packer (not shown) a tail pipe or other well tubular may be used for this purpose.
- a cable-less communication system such as an acoustic system or a system that uses the tubing as an antenna may be used for the data transfer from and power supply to the monitoring device 4.
- the device 4 can therefore be easily installed in both existing and new wells for permanent downhole use.
- the device can also be equipped with other sensors for measuring physical characteristics of the pore fluids, such as pressure and temperature.
- the monitoring device 4 offers high installation flexibility and is but a small obstruction in the wellbore. Due to its tubular design free access to the wellbore below the device 4 is provided. This also allows the use of several monitoring devices 4 at various depths in a single well 1, e.g. to monitor the fluid interfaces of stacked reservoirs and/or to monitor the oil/water interface below, and the oil/gas interface above, an oil bearing reservoir formation. In reservoirs where steam or other fluid injection takes place the device 4 may be used to monitor a breakthrough of steam or another injection fluid into the production well 1.
- Fig. 4 shows a vertical production well 20 in which a monitoring device 21 which is similar to the device 4 of Figs. 1-3 is mounted.
- a monitoring device 21 which is similar to the device 4 of Figs. 1-3 is mounted.
- three slimhole side-track wells 22 have been drilled into the reservoir formation 23.
- Each side-track well 22 is equipped with a monitoring device 24 which is shown at an enlarged scale in Fig. 5.
- the device 24 comprises a tubular sleeve 25 which is equipped with a pair of expandable packers 26 that are pressed against the formation surrounding the wellbore of the side track well 22.
- annular measuring chamber 27 is formed around the sleeve 25 and between the packers 26 to which chamber 27 pore fluids from the surrounding formation have free access but which chamber is hydraulically isolated from the rest of the wellbore.
- the outer surface of the sleeve 25 is equipped with an array of capacitor and/or other sensors (not shown) which operate in the same manner as described with reference to Figs. 1-3.
- the array of sensors is connected to means for displaying the measured fluid characteristics at the surface (not shown) by means of one or more electrical or optical signal transmission cables 28.
- the well and sensor configuration shown in Figs. 4 and 5 is suitable for monitoring the gas/water (CH 4 /H 2 O) interface at various locations in and at various distances away from the gas production well 20 which allows an adequate mapping of the variations of the gas/water interface throughout the reservoir formation 23 as a result of water coning or other reservoir depletion effects.
- Fig. 6 shows a schematic vertical sectional view of a horizontal oil production well 30 which extends through an oil bearing reservoir formation 31.
- a pair of parallel faults 34 exist in the reservoir and surrounding formations and as a result of variations in the fluid flow conditions the oil/water and gas/oil interfaces are different at each side of each fault 34.
- Each side-track well 35 is equipped with an elongate monitoring device 36 of the same type as described in detail with reference to Fig. 5 and the other parts of the side-track wells 35 are filled with cement to prevent uncontrolled production via the side-track wells 35.
- the well and sensor configuration shown in Fig. 6 enables an adequate and continuous mapping of the oil/water and oil/gas and/or gas/water surfaces in a faulted reservoir formation which is traversed by a horizontal or inclined production well.
- Fig. 7 is a schematic vertical sectional view of a faulted oil bearing reservoir formation 40 which is traversed by a vertical oil production well 41 which is equipped with an upper and a lower monitoring device 42 and 43, respectively, which devices are of the same type as shown in Fig. 2.
- the monitoring devices 42 and 43 are located in the regions of the oil/gas and oil/water interfaces in the reservoir formation 40 in the vicinity of the production well 41.
- a slimhole side-track well 46 has been drilled from the production well 41 into the reservoir formation 40 in a direction substantially parallel to the faults 49.
- the side-track well 46 contains an upper and a lower monitoring device 47 and 48, respectively, for monitoring the gas/oil and oil/water interface at the top and bottom of the oil bearing reservoir formation.
- the monitoring devices 47 and 48 are of the same type as shown in Fig. 5 and the other parts of the side-track well 46 are cemented to prevent uncontrolled production via the side-track well 46.
- Fig. 7 enables an adequate and continuous mapping of the gas/oil and oil/water interfaces in a faulted reservoir formation 40 which is traversed by a vertical or inclined oil production well 41.
- the monitoring device and method according to the present invention can be used to monitor the gas, oil and/or water interfaces at any desired location in an underground formation. They can be used to improve and update the reservoir models and make real-time reservoir imaging and management possible.
Landscapes
- Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- Geology (AREA)
- Mining & Mineral Resources (AREA)
- Physics & Mathematics (AREA)
- Environmental & Geological Engineering (AREA)
- Fluid Mechanics (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Geophysics (AREA)
- Geophysics And Detection Of Objects (AREA)
Priority Applications (15)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP97201092A EP0870900A1 (de) | 1997-04-09 | 1997-04-09 | Verfahren und Gerät zur Bohrlochüberwachung |
EG39098A EG21490A (en) | 1997-04-09 | 1998-04-05 | Downhole monitoring method and device |
CN98803982A CN1252118A (zh) | 1997-04-09 | 1998-04-08 | 井下监控的方法和装置 |
ARP980101608A AR012365A1 (es) | 1997-04-09 | 1998-04-08 | Un metodo y un dispositivo para monitorear en un fondo de pozo las caracteristicas fisicas de fluidos. |
CA002284997A CA2284997C (en) | 1997-04-09 | 1998-04-08 | Downhole monitoring method and device |
US09/056,960 US6098020A (en) | 1997-04-09 | 1998-04-08 | Downhole monitoring method and device |
EP98922712A EP0973996B1 (de) | 1997-04-09 | 1998-04-08 | Verfahren und gerät zur bohrlochüberwachung |
PCT/EP1998/002187 WO1998045574A1 (en) | 1997-04-09 | 1998-04-08 | Downhole monitoring method and device |
DK98922712T DK0973996T3 (da) | 1997-04-09 | 1998-04-08 | Fremgangsmåde og indretning til overvågning nede i et borehul |
AU75255/98A AU730117B2 (en) | 1997-04-09 | 1998-04-08 | Downhole monitoring method and device |
DE69807202T DE69807202T2 (de) | 1997-04-09 | 1998-04-08 | Verfahren und gerät zur bohrlochüberwachung |
IDW991175A ID22833A (id) | 1997-04-09 | 1998-04-08 | Metoda dan alat pemantauan lubang pemboran |
EA199900905A EA001569B1 (ru) | 1997-04-09 | 1998-04-08 | Способ контроля физических характеристик текучих сред в нисходящей скважине и устройство для его осуществления |
NO994909A NO994909L (no) | 1997-04-09 | 1999-10-08 | Fremgangsmåte og innretning for overvåking i et borehull |
OA9900223A OA11202A (en) | 1997-04-09 | 1999-10-08 | Downwhole monitoring method and device |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP97201092A EP0870900A1 (de) | 1997-04-09 | 1997-04-09 | Verfahren und Gerät zur Bohrlochüberwachung |
PCT/EP1998/002187 WO1998045574A1 (en) | 1997-04-09 | 1998-04-08 | Downhole monitoring method and device |
Publications (1)
Publication Number | Publication Date |
---|---|
EP0870900A1 true EP0870900A1 (de) | 1998-10-14 |
Family
ID=26070314
Family Applications (2)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP97201092A Withdrawn EP0870900A1 (de) | 1997-04-09 | 1997-04-09 | Verfahren und Gerät zur Bohrlochüberwachung |
EP98922712A Expired - Lifetime EP0973996B1 (de) | 1997-04-09 | 1998-04-08 | Verfahren und gerät zur bohrlochüberwachung |
Family Applications After (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP98922712A Expired - Lifetime EP0973996B1 (de) | 1997-04-09 | 1998-04-08 | Verfahren und gerät zur bohrlochüberwachung |
Country Status (2)
Country | Link |
---|---|
EP (2) | EP0870900A1 (de) |
WO (1) | WO1998045574A1 (de) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2015050660A1 (en) * | 2013-10-04 | 2015-04-09 | Baker Hughes Incorporated | Downhole monitoring using magnetostrictive probe |
US9598642B2 (en) | 2013-10-04 | 2017-03-21 | Baker Hughes Incorporated | Distributive temperature monitoring using magnetostrictive probe technology |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6441618B2 (en) * | 2000-02-04 | 2002-08-27 | Schlumberger Technology Corporation | Method and apparatus for monitoring the advance of seawater into fresh water aquifers near coastal cities |
Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2564198A (en) * | 1945-01-15 | 1951-08-14 | Stanolind Oil & Gas Co | Well testing apparatus |
US2605637A (en) * | 1949-07-28 | 1952-08-05 | Earle D Rhoades | Surveying of subsurface water tables |
FR1322402A (fr) * | 1962-03-20 | 1963-03-29 | Petroleum Res Corp | Système d'analyse de couches de terrains multiples |
DE2621142A1 (de) * | 1976-05-13 | 1977-11-17 | Kavernen Bau Betriebs Gmbh | Verfahren und einrichtung zur bestimmung der teufe des trennspiegels blanketmedium-salzsole bei der herstellung von kavernen |
FR2435025A1 (fr) * | 1978-09-04 | 1980-03-28 | Solmarine | Dispositif de mesure de variations de pression |
WO1996023957A1 (en) * | 1995-02-02 | 1996-08-08 | Mobil Oil Corporation | Method of monitoring fluids entering a wellbore |
-
1997
- 1997-04-09 EP EP97201092A patent/EP0870900A1/de not_active Withdrawn
-
1998
- 1998-04-08 EP EP98922712A patent/EP0973996B1/de not_active Expired - Lifetime
- 1998-04-08 WO PCT/EP1998/002187 patent/WO1998045574A1/en active IP Right Grant
Patent Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2564198A (en) * | 1945-01-15 | 1951-08-14 | Stanolind Oil & Gas Co | Well testing apparatus |
US2605637A (en) * | 1949-07-28 | 1952-08-05 | Earle D Rhoades | Surveying of subsurface water tables |
FR1322402A (fr) * | 1962-03-20 | 1963-03-29 | Petroleum Res Corp | Système d'analyse de couches de terrains multiples |
DE2621142A1 (de) * | 1976-05-13 | 1977-11-17 | Kavernen Bau Betriebs Gmbh | Verfahren und einrichtung zur bestimmung der teufe des trennspiegels blanketmedium-salzsole bei der herstellung von kavernen |
FR2435025A1 (fr) * | 1978-09-04 | 1980-03-28 | Solmarine | Dispositif de mesure de variations de pression |
WO1996023957A1 (en) * | 1995-02-02 | 1996-08-08 | Mobil Oil Corporation | Method of monitoring fluids entering a wellbore |
Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2015050660A1 (en) * | 2013-10-04 | 2015-04-09 | Baker Hughes Incorporated | Downhole monitoring using magnetostrictive probe |
GB2533255A (en) * | 2013-10-04 | 2016-06-15 | Baker Hughes Inc | Downhole monitoring using magnetostrictive probe |
US9422806B2 (en) | 2013-10-04 | 2016-08-23 | Baker Hughes Incorporated | Downhole monitoring using magnetostrictive probe |
US9598642B2 (en) | 2013-10-04 | 2017-03-21 | Baker Hughes Incorporated | Distributive temperature monitoring using magnetostrictive probe technology |
GB2533255B (en) * | 2013-10-04 | 2020-04-01 | Baker Hughes Inc | Downhole monitoring using magnetostrictive probe |
Also Published As
Publication number | Publication date |
---|---|
WO1998045574A1 (en) | 1998-10-15 |
EP0973996A1 (de) | 2000-01-26 |
EP0973996B1 (de) | 2002-08-14 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US6098020A (en) | Downhole monitoring method and device | |
CA2501480C (en) | System and method for installation and use of devices in microboreholes | |
CA2419506C (en) | Formation testing apparatus with axially and spirally mounted ports | |
US8302687B2 (en) | Apparatus for measuring streaming potentials and determining earth formation characteristics | |
US5353873A (en) | Apparatus for determining mechanical integrity of wells | |
US9008971B2 (en) | Measurement of hydraulic head profile in geologic media | |
US9187957B2 (en) | Method for motion compensation using wired drill pipe | |
US5610331A (en) | Thermal imager for fluids in a wellbore | |
US6644402B1 (en) | Method of installing a sensor in a well | |
US6230800B1 (en) | Methods and apparatus for long term monitoring of a hydrocarbon reservoir | |
MX2010011148A (es) | Metodo para estimar la permeabilidad de formaciones usando mediciones por lapsos de tiempo. | |
US3895527A (en) | Method and apparatus for measuring pressure related parameters in a borehole | |
GB2156403A (en) | Method and apparatus for determining formation pressure | |
EP0973996B1 (de) | Verfahren und gerät zur bohrlochüberwachung | |
JP3353714B2 (ja) | 間隙水計測方法及び装置 | |
MXPA99008940A (en) | Downhole monitoring method and device | |
WO2011033257A1 (en) | Downhole measurement apparatus | |
US20230349285A1 (en) | Measuring water level in highly deviated or horizontal hydrocarbon well sections | |
EP2459841A2 (de) | Messvorrichtung | |
GB2443374A (en) | Instrumentation for downhole deployment valve | |
GB2441901A (en) | A method of using a downhole deployment valve |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
PUAI | Public reference made under article 153(3) epc to a published international application that has entered the european phase |
Free format text: ORIGINAL CODE: 0009012 |
|
AK | Designated contracting states |
Kind code of ref document: A1 Designated state(s): GB |
|
AKX | Designation fees paid | ||
STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN |
|
18D | Application deemed to be withdrawn |
Effective date: 19990415 |