Information
-
Patent Grant
-
6397864
-
Patent Number
6,397,864
-
Date Filed
Monday, March 8, 199925 years ago
-
Date Issued
Tuesday, June 4, 200222 years ago
-
Inventors
-
Original Assignees
-
Examiners
-
CPC
-
US Classifications
Field of Search
US
- 134 166 R
- 134 167 R
- 134 168 C
- 134 167 C
- 134 166 C
- 134 169 R
- 134 198
- 015 10431
- 015 10405
- 015 10416
- 166 222
- 166 223
- 166 171
- 166 172
- 166 56
-
International Classifications
-
Abstract
An apparatus for cleaning subterranean wellbores is described. The apparatus comprises a rotatable jet head with less than five axially separated nozzles through which an abrasive fluid is discharged. The nozzles are mounted with an axial separation of preferably more than 0.5 times the nozzle diameter.
Description
The present invention relates to an improved nozzle arrangement for a jet drilling apparatus. The invention particularly relates to such an apparatus as applied for cleaning of surface and subterranean pipes and boreholes for hydrocarbon reservoir exploration and production, more particularly to the removal of scale and other deposits from the inside diameter of well tubulars and boreholes.
BACKGROUND OF THE INVENTION
It has been common practice for many years to run a continuous reeled pipe (known extensively in the industry as “coil tubing”) into a well to perform operations utilising the circulation of treating and cleanout fluids such as water, oil, acid, corrosion inhibitors, hot oil, nitrogen, foam, etc. Coil tubing, being continuous rather than jointed, is run into and out of a well with continuous movement of the tubing through a coil tubing injector.
Coil tubing is frequently used to circulate cleanout fluids through a well for the purpose of eliminating sand bridges, scale, and similar downhole obstructions. Often such obstructions are very difficult and occasionally impossible to remove because of the inability to rotate the coil tubing and drill out such obstructions. These well tubulars vary from unperforated and perforated pipe, large diameter casing, production tubing, and slotted or wire-wrapped well liner. Well tubulars often become plugged or coated with corrosion products, sediments and hydrocarbon deposits. The deposits may consist of silicates, sulphates, sulphide, carbonates, calcium, and organic growth.
It is desirable to perform drilling type operations in wells through use of coil tubing which can be run into and removed from a well quickly in addition to performing the usual operations which require only the circulation of fluids. The same types of well servicing can also be performed with various small diameter work strings. The present invention may be used with such work strings and is not limited to coil tubing.
High pressure fluid jet systems have been used for many years to clean the inside diameter of well tubulars. Examples of such systems are disclosed in the following U.S. Pat. Nos. 3,720,264, 3,811,499, 3,829,134, 3,850,241, 4,088,191, 4,349,073, 4,441,557, 4,442,899, 4,518,041, 4,919,204, 5,181,576 or 5,337,819.
In U.S. Pat. No. 3,720,264, there is disclosed a jet tool for cleaning a liner. The jet tool includes three pairs of jet nozzles arranged in a staggered manner with each pair of nozzles slightly rotated with respect to the others.
In U.S. Pat. No.4,442,899, the nozzles are circumferentially spaced from each other about 90 degrees and separated such as to form a spiral.
U.S. Pat. No. 5,337,819 discloses a washing tool for removing internal deposits in tubing parts and components in wells for oil and gas production. The known tool comprises an actuation sleeve which has lateral dimensions related to the deposits to be removed. The sleeve actuates a valve to discharge a fluid jet through layers of circumferentially arranged discharge nozzles.
In view of the above cited prior art, it is an object of the invention to provide an improved fluid jet cleaning tool to remove scale and other deposits from the inside diameter of tubulars and boreholes for the exploration and production of hydrocarbon reservoirs. It is a particular object of the invention to provide a novel nozzle arrangement for such a fluid jet cleaning tool.
SUMMARY OF THE INVENTION
According to the present invention there is provided a fluid jet cleaning apparatus for cleaning of tubulars and boreholes for hydrocarbon reservoir exploration and production, said apparatus comprising a rotatable nozzle head including less than five axially separated nozzles mounted on a part of a lower end of a hollow tubular.
It has been recognised that the number of nozzles of a well cleaning tool can be reduced to less than five, preferably less than four without significant loss of performance.
Furthermore, it was found that the efficiency of the tool can be increased over tools with an equal number of nozzles by axially separating the nozzles. The preferred axial separation between two adjacent nozzles is larger than 0.5 times the nozzle diameter, but smaller than 20 times, more preferably 10 times, the nozzle diameter.
The preferred angular separation is either 180 degrees in case of two nozzles, 120 degrees in case of three nozzles or for four nozzles, a separation of 180 degrees between a pair of nozzles with the second pair preferably rotated by 90 degrees with respect to the first pair of nozzles.
The cleaning tool may also comprise a gauge defining sleeve with an essentially annular edge of a width of less than 10 mm, preferably 5 mm. The nozzle located closest to the sleeve is targeted at an area of the tubular or wellbore immediately below the sleeve member.
These and other features of the invention, preferred embodiments and variants thereof, and advantages will become appreciated and understood by those skilled in the art from the detailed description and drawings following below.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1
shows a jet cleaning tool connected to a coiled tubing;
FIG. 2
shows a jet cleaning tool in accordance with a preferred embodiment of the invention; and
FIG. 3
illustrates the improved efficiency of the novel nozzle arrangement over known arrangements.
MODE(S) FOR CARRYING OUT THE INVENTION
The invention is now described with reference to the attached drawings.
A typical well cleaning operation is illustrated by FIG.
1
. The subsurface equipment for well cleaning comprises a coiled tubing reel
11
usually mounted on a truck
12
. Connected to the reel there is a cleaning fluid tank
13
, a reservoir and feeder for the abrasive material
14
. A mixer
15
generates the abrasive slurry applied for deposit removal. A pump unit
16
generates the pressure to circulate the slurry through the coiled tubing
17
and the wellbore
18
.
The coiled tubing
17
is fed through the Blow-out Preventer (BOP) stack
181
into the well tubulars
182
. A return pipe
171
at the upper end of the well tubulars closes the flow loop through which the cleaning fluid is pumped. Also included in the flow loop (but not shown) are separators to recover the cleaning fluid and/or the abrasives.
In operation, the coiled tubing with a jetting head
172
at its end is lowered into the well
18
to a predetermined depth at which deposits
183
are to be removed. Then the abrasive containing slurry is discharged through the nozzles of the jetting head removing scale at a rate depending on the deposits, jetting speed and stand-off.
The basic components of a nozzle arrangement in accordance with the invention are illustrated in FIG.
2
. There is shown the lower part
20
of a hollow tube representing a drillstring or a coiled tubing. Attached to the tube is a sleeve member
22
. The sleeve member in the described example is made of a solid cylinder of engineering steel with a frustro-conically shaped upper end and an outer diameter of 75 mm and a centre bore
221
of 45 mm. An alternative material may be tungsten carbide or other steels of sufficient hardness.
Further components of the system are a nozzle head
24
which carries two axially separated nozzles
241
,
242
arranged with a 180 degrees angular separation. The nozzle head is rotatably mounted on the drillstring
20
. In operation the first nozzle
241
removes only part of the debris
261
, leaving material at a small angle with respect to the wall of the tubular
26
. The efficiency of the operation of the second nozzle
242
was found to be linked to this angle (target angle) with increased efficiency at smaller target angles. The second nozzle
242
is directed to the area
223
immediately below the sleeve.
To demonstrate the improved efficiency of the novel arrangements, tests were carried out cutting Stancliffe sandstone and cleaning scaled tubing. Axial separations between the nozzles
241
and
242
were 0, 6, and 20 mm at an angular separation of 180 degrees. Other test conditions were
|
Nozzle diameter:
2.8
mm
|
Stand-off:
15
mm
|
Nozzle pressure drop:
130
B
|
Vessel pressure:
210
B
|
Jetting media (for Stancliffe):
water
|
Jetting media (for scale):
calcite pellets
|
Rotary speed:
80
rpm
|
|
The results of the test are shown in
FIG. 3
as material removed versus nozzle separation at various tool propagation speeds. A clear tendency for improved cutting efficiency at larger nozzle separation is demonstrated enabling operations at higher tool propagation speed for the same level of material removal.
Claims
- 1. Fluid jet cleaning apparatus for cleaning of tubulars and boreholes for hydrocarbon reservoir exploration and production, said apparatus comprising:mounted on a part of a lower end of a hollow tubular, a nozzle head rotatable with respect to the lower end of the hollow tubular, the nozzle head including less than five axially and angularly separated nozzles, each nozzle being spaced apart from each other nozzle by a predetermined distance in a direction along the central axis of the hollow tubular and a predetermined angle as measured from the central axis.
- 2. The apparatus of claim 1, wherein the number of nozzles is two or three.
- 3. The apparatus of claim 1, wherein the axial separation between two nozzles is at least 0.5 times the nozzle diameter.
- 4. The apparatus of claim 1, wherein the nozzles are arranged clockwise or counterclockwise with an essentially uniform angular spacing.
- 5. The apparatus of claim 1, wherein the angular separation of the nozzles is 180 degrees for a pair of nozzles or 120 degrees for three nozzles.
- 6. The apparatus of claim 5, wherein the leading edge has openings allowing fluid to pass through the sleeve member.
- 7. The apparatus of claim 1, further including a gauge defining sleeve member arranged such that a fluid jet discharged from one of the nozzles targets an area of the tubular or wellbore immediately below said sleeve member.
- 8. The apparatus of claim 7, wherein sleeve member has an essentially annular edge of a width of less than 10 mm.
- 9. The apparatus of claim 7, wherein sleeve member has an essentially annular edge of a width of less than 5 mm.
- 10. The apparatus of claim 1 attached to a lower part of coiled tubing.
Priority Claims (1)
Number |
Date |
Country |
Kind |
9804690 |
Mar 1998 |
GB |
|
US Referenced Citations (56)