communicates the interior of the tubing with the casing annulus above packer 24.
The subsurface equipment, as illustrated in Fig. 5, is then pressure checked on both the casing and the tubing sides to determine any possible leaks. It is important that no leaks occur past or through the packer 12 positioned above perforating formation B.
The separation tool or plug 27 is now removed by a conventional wire line retrieving assembly. The tubing section 25 is disconnected at 14 and the assembly as shown is raised until the lower end of tubing section 25 is positioned above the upper formation A as illustrated in Fig. 6.
The tubing string 15 is then swabbed to remove fluid so that a pressure differential is created between the pressure of casing 11 and the pressure of formation A so that upon perforation of the casing adjacent formation A the productive fluids will immediately flow into the casing and tubing. The fluids from formation B are at this time isolated by means of plug 20. A gun perforator such as 19 is lowered through the tubing to a position adjacent formation A, as shown in Fig. 7, and the casing perforated. It will be seen at this point that by means of plug 20 and packer 12 the fluids from upper zone A are completely isolated from the fluids from formation B. • The tubing string 15 is then lowered and the two sections of the releasable coupling assembly 14 are coupled together. The port closing member 17 is run in on a wire line and placed so as to close port 16 and blank off fluid flow from tubing 15 to pipe 26 or vice versa.
A wire line retrieving tool is then run in through tubing 15 and plug member 20 in landing recess 14' of releasable coupling assembly 14 is removed as shown in Fig. 8.
Lower zone B is now allowed to produce through the tubing and through the casing until the workover or drilling fluids are removed from the well bore with the fluid flow path being up through the tubing and also through the casing annulus C via side port 22 of nipple 21. After the casing and tubing has been cleared of workover fluid, a separation tool 27a, as shown in Fig. 9, is run in on a wire line and set in side port landing nipple 21. Separation tool 27a is slightly modified from that of separation tool 27 in that it is not of sufficient length to close off the side ports 22 but plugs off the bore of the tubing above the side port 22.
The port closing member 17 is now removed to open port 16. The well is now in condition to produce from the two zones A and B with the fluids from formation B flowing into the casing 11 below packer 12 through production tube 13, tubing section 25 and out through ports 22 in side port landing nipple 21 and up through the tubing casing annulus above packer 24. The production fluids from formation A flow into annulus C of casing 11 through pipe conduit 26 and then into the tubing by way of the port 16 above the separation tool 27a. : It will be seen that during all of the various steps of the present method the fluids from each of the formations A and B have been kept completely separated one from the other even at the instant of perforation of the different formations.
At times it may be desirable to perforate only the upper zone with a lower casing pressure than formation pressure. This is shown in Fig. 10 which is somewhat similar to the other Figures 1 through 9.
Referring to Fig. 10, the procedure is as follows. Prior to positioning the lower packer 12, the casing opposite the lower formation B is perforated with any type of perforator desired which is lowered through the casing.
After the lower formation B is perforated (the production from which is held in check by the drilling mud in the casing), a packer 12 such as a Baker Model D retainer production packer described supra is then set in the casing between the formations A and B. The
equipment used in this Step is practically identical with that shown in the previous Figures 5 through 9.
After the formation B has been perforated and the packer 12 set in the casing, the tubing string is then run
5 back in the hole. The tubing string 15 is equipped practically the same as the previous figures with production tube 13 locked in packer 12 with its upper end extending above packer 12 and connected to extension pipe 25 by means of releasable coupling 14. The upper end of
10 extension tube 25 is connected into the lower end of a packer 24 which is positioned within the casing 11 a substantial distance above formation A. The tubing above packer 24 has contained therein a side port landing nipple
21 provided with side ports 22 and the tubing is also 15 provided with closable port 16 which fluidly communicates
with elbow connection 18. Pipe conduit 26, as in the previous figures, is connected into elbow connection 18 and extends downwardly through packer 24 into the annulus C between packers 12 and 24.
20 After the assembly as shown in Fig. 10 is positioned, a plug 20 is run in on a wire line and landed in landing recess 14', thus plugging off the lower formation B from the tubing above releasable coupling 14. A separation tool 27 is then lowered by means of wire line and landed
25 in side port landing nipple 21 to plug off the side ports
22 and also the central bore of the tubing. The equipment is at this time pressure checked on both the tubing and the casing sides to be sure that the packers and plug members are functioning properly. The separation
30 too! is then removed and the tubing is swabbed to reduce the pressure within the tubing so that the pressure within the casing and tubing is less than the pressure of the formation which is to be perforated. After this differential pressure has been created, the upper assembly is un
38 latched at the releasable coupling assembly 14 and the assembly is raised enough to clear the upper zone. A gun perforator' is then lowered through the tubing to a position in the casing adjacent the upper formation A and the casing perforated. The tubing gun is then re
*0 moved and the assembly is again lowered and coupled together at the releasable coupling assembly 14. The upper zone is now in a condition for producing and is allowed to do so until all the adjacent casing and tubing is clear of workover fluids above packer 12.
45 At this time a port closing member 17 is run in by wire line and set in tubing 15 to close off the passage through pipe conduit 26. After the port closing member 17 has been placed, the bottom plug 20 in landing recess 14' is removed and the lower zone is allowed to produce
50 through the tubing until it is clear of workover fluids such as drilling mud. After it is determined that the well is clear of workover fluids, a separation tool such as 27a is run in by wire line and landed in landing nipple 21. This separation tool, as previously described, closes
55 the bore of the tubing at this point but leaves the ports 22 open. The closure member 17 adjacent port 16 is then removed and the zones are allowed to produce separately with the flow paths from each zone being identical with those previously described with regard to Fig. 9.
60 It will be seen from the above disclosure that the objects as previously set out in the specification have been accomplished, that is, the fluids from each of the formations have been entirely isolated at all times from each other even on the instant of perforating the casing ad
65 jacent each of the formations. It will also be seen that a differential pressure has been created between the casing and formation pressure previous to perforating so that the production fluids from the formations A and B immediately flow into the casing upon perforating.
TO The present apparatus and method is quite advantageous in several respects. In creating a lower pressure in the casing compared to that of formation pressure, the producing fluids from the formation flow immediately into the casing Upon perforating. This eliminates the
7S contamination of the formation by drilling fluids and the