Recent testing procedures, equipment and techniques are being used in the North Sea and other areas to:
Save rig time by eliminating as many as three round trips of the drill pipe,
Provide better well control while perforating underbalanced,
Clean the well up faster by perforating with the test tools in the hole,
Provide better reservoir evaluation by permitting longer test (both draw-down and build-up permitting longer test (both draw-down and build-up analysis can be utilized),
Evaluate treatments by retesting immediately following the treating job,
Permit treating immediately after the test without Permit treating immediately after the test without subjecting the formation to the completion fluid,
Permit retesting after the treatment without subjecting Permit retesting after the treatment without subjecting the formation to the completion fluid, and
Provide maximum safety by utilizing both surface and downhole valves.
New large inside diameter (2.25 inch (57-15 mm)) temperature-pressure recorder running cases coupled with field proven full opening mechanically operated testing string, or the more recent pressure operated string, wire line retrievable pressure recorders and quick connect-disconnect lubricator and other surface equipment has proven to be reliable and safe. This arrangement is helping operators save expensive rig time and provide better data. provide better data. Several jobs where multiple operations were performed on one trip in the hole are discussed, performed on one trip in the hole are discussed, indicating the feasibility and savings possible with multi-operation jobs. Current equipment, techniques, capabilities and limitations are discussed. New equipment (such as pressure operated downhole tools, full opening samplers and safety valves) and new techniques are also discussed.
Two new pieces of surface equipment are currently being used in conjunction with the large inside diameter subsurface equipment. The Quick Disconnect makes it easy to switch from wire line lubricator to the testing string, etc. The Remote Control Safety Valve provides safe, easy well control from the rig floor. provides safe, easy well control from the rig floor. Both tools are available for standard service (15,000 psi (103.4 MPa) working pressure, 20,000 psi (137–914 Pa) psi (103.4 MPa) working pressure, 20,000 psi (137–914 Pa) test) and for sour gas service (10,000 psi (68.9 MP working pressure, 15,000 rsi (103.4 MPa) test). As the other surface equipment has been discussed in previous papers, it will not be covered here. papers, it will not be covered here.
A Quick Disconnect tool is now available that helps reduce rig time and makes it easier to install a wire line lubricator when perforating or running and retrieving wire line pressure recoders through the full opening downhole tools. The tool has two top halves and one bottom half. One top half is installed on the bottom end of the upper part of the testing surface equipment. The other top half is installed on the bottom end of the wire line lubricator. The lower half of the Quick Disconnect is installed on the top end of the lower part of the surface equipment and is used for both testing and wire line operations. As shown in Figure 1, the upper part of the testing string (Figure 1-A) is made upon the lower part of the surface equipment (Figure 1-B) for setting the packer, landing the string on the Sub-Sea Test Tree (on floating vessels), and opening the Tester Valve. With the Tester Valve open, the surface equipment Master Valve is closed. The course thread on the top half of the Quick Disconnect can then be quickly loosened with a hammer and backedoff by hand, eliminating the common problem of trying to raise the rig tongs up to the tool. Once the top of the testing surface equipment is removed, the wire line lubricator (with the second top half of the Quick Disconnect already installed, Figure 1-C) can be quickly made up on the lower portion of the surface equipment. As the Quick Disconnect is made up, splines between the two halves engage to help prevent accidentally backing off the course thread. The Master Valve is opened and the perforating gun run. After perforating, the gun is pulled into the lubricator, the Master Valve closed and the surface equipment is quickly switched to the testing system. When the pressure operated downhole tools are used, additional safety is provided while pulling the perforating gun since the pressure operated Tester Valve can be closed immediately after the gun is above the Tester Valve.