This invention relates to apparatus and methods for cutting openings in wells, and more particularly to a perforating apparatus which can cut slots in a well casing.
There are a number of methods used in perforating wells which are well known. One of those methods includes utilizing a jetting tool through which a jetting fluid passes at a pressure high enough to cut openings, or perforate the well casing. The jetting tool, typically including a plurality of jetting nozzles, is lowered into the well on the tubing string through which jetting fluid is displaced.
It is often desirable to cut slots in the wells as opposed to simply creating holes, or generally circular areas. Slots create a greater area through which treating fluid can be passed and also a greater area for the return of production fluid from the formation. One technique that has been attempted to cut slots in casing requires mounting jet nozzles in a spring-loaded tool. Such an arrangement is shown in
The current invention is directed to an apparatus for cutting openings in the wall of a well. The apparatus is more particularly directed to perforating or cutting slots in a casing. The apparatus includes a mandrel defining a flow passage therethrough. The mandrel is lowered into the well on a tubing, which may be for example but is not limited to a coiled tubing. The mandrel has a plurality of slots defined therein and is plugged at a lower end thereof so that the fluid flowing through the mandrel is forced through the slots.
A sleeve, which may be referred to as a jetting sleeve, is slidably disposed about the mandrel. The jetting sleeve is movable on the mandrel between first and second positions. The jetting sleeve has a plurality of jetting openings therein. Jetting fluid is displaced downwardly through the tubing into the mandrel. The jetting fluid passes through the slots in the mandrel and the jetting openings in the jetting sleeve, and will cut openings in the wall of the well, such as slots in the casing in the well. The jetting openings preferably have jetting nozzles therein which extend into and travel in the slots defined in the mandrel.
The jetting fluid is displaced through the mandrel at a rate sufficient to cause the jetting sleeve to move axially on the mandrel from the first position toward the second position thereof, which preferably is in the direction of the jetting fluid through the mandrel. The jetting fluid will exit the mandrel through the slots and will pass through the jetting openings. As the jetting sleeve moves on the mandrel, it will cut slots in the wall of the well which will match the shape of the slot in the mandrel. The apparatus includes a means for applying force to a second end of the jetting sleeve, such as a spring, to push the jetting sleeve towards the first position thereof on the mandrel. The rate of the jetting fluid can be slowed so that the spring will move the jetting sleeve toward the first position thereof. Reciprocation of the sleeve on the mandrel causes the slots of the desired shape to be cut in the well.
The apparatus may include a metering device disposed in an annular chamber for controlling the rate of the longitudinal movement of the sleeve. The metering device may comprise an annular ring with first and second longitudinal passageways defined therein. A fluid restrictor is disposed in one of the first or second passageways for controlling the rate of movement of the sleeve while the other longitudinal passageway may have a check valve disposed therein. The metering device is positioned in the annular chamber defined by the jetting sleeve and the mandrel.
Referring now to the figures and more particularly to
Referring now to
Mandrel 36 has upper end 42 and lower end 44. Mandrel 36 may be threadedly connected at lower end 44 to a bull plug 46 which has a closed end 47 to prevent the flow of fluid therethrough. Any device with a closed end to prevent fluid flow downward therethrough may be connected to mandrel 36.
Mandrel 36 is preferably a stepped mandrel and thus has a first or upper portion 48 having a first outer diameter 50 and a second or lower portion 52 having a second outer diameter 54. Second outer diameter 54 is smaller than first outer diameter 50 and a downward facing shoulder 56 is defined by and extends between first and second outer diameters 50 and 54. Mandrel 36 defines a central passageway 58. Fluid, such as jetting fluid of a type known in the art may be communicated into central passageway 58 from tubing 20.
Mandrel 36 has a plurality of slots 60 therethrough. Slots 60 preferably extend from shoulder 56 toward lower end 44 of mandrel 36. Slots 60 thus have first or upper end 62 and second or lower end 64 defining a length 66 therebetween.
There are preferably four slots 60 equally spaced around the circumference of mandrel 36. As shown in the expanded plan view of the exterior surface of mandrel 36, slots 60 may be vertical slots as shown in
Jetting sleeve 40 has first or upper end 70 and second or lower end 72. Jetting sleeve 40 has first and second portions 74 and 76, respectively. First portion 74 defines a first inner diameter 78 and second portion 76 defines a second inner diameter 80. First portion 74 of jetting sleeve 40 is slidably disposed about first portion 48 of mandrel 36. A seal 82 is disposed in a groove 84 in mandrel 36 above slots 60 so that first portion 48 of mandrel 36 is slidably and sealingly engaged by first portion 74 of jetting sleeve 40. A seal 86 is disposed in a groove 88 in jetting sleeve 40. Seal 86 is positioned below lower end 64 of slots 60 so that jetting sleeve 40 slidably and sealingly engages mandrel 36 below slots 60 in the upper and lower positions of jetting sleeve 40. A third inner diameter 90 is defined on second portion 76 of jetting sleeve 40. An annular space 92 having first or upper end 94 and second or lower end 96 is defined by third inner diameter 90 on jetting sleeve 40 and by second outer diameter 54 on mandrel 36. A seal, such as an O-ring seal 98 is disposed in a groove 100 in jetting sleeve 40 below the lower end 96 of annular space 92. A metering device 102 is disposed in annular space 92 and preferably is fixed to mandrel 36.
Metering device 102 divides annular space 92 into an upper chamber 104 and a lower chamber 106 which may be referred to as upper and lower oil chambers 104 and 106, respectively. Metering device 102 may comprise metering cartridge 107 having first and second longitudinal flow paths 108 and 110 extending from the upper end 112 to the lower end 114 thereof.
First longitudinal flow path 108 has a first check valve 116 disposed therein. Second longitudinal flow path 110 has a second check valve 118 disposed therein and has a flow restrictor 120 such as for example a VISCO JET restrictor from Lee Company disposed therein and positioned beneath second check valve 118. A spring 122 is positioned between lower end 72 of jetting sleeve 40 and an upper end 45 of bull plug 46. Upper end 45 may be referred to as a shoulder or platform 45 against which spring 122 rests. Spring 122 urges or biases jetting sleeve 40 towards and into the first position shown in
Jetting sleeve 40 has a plurality of jetting openings 124 each of which preferably has a jet or jetting nozzle 126 disposed therein. In an exemplary embodiment, jetting sleeve 40 has the same number of jetting openings 124 and jetting nozzles 126 as slots 60 in mandrel 36. Jetting nozzles 126 may extend from jetting openings 124 into slots 60 and thus travel in slots 60 between the first, or upper position shown in
In operation, jetting tool 10 is lowered into well 15 until it is adjacent the location that is to be perforated, which will likely be adjacent an interval or formation such as formation 34 shown in
In an exemplary embodiment, the fluid flowing through mandrel 36 will cause jetting sleeve 40 to move downwardly relative thereto, from its first position shown in
Once the second position shown in
Thus, the present invention is well adapted to carry out the object and advantages mentioned as well as those which are inherent therein. While numerous changes may be made by those skilled in the art, such changes are encompassed within the spirit of this invention as defined by the appended claims.