Page 89 - Drilling Technology in Nontechnical Language
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80              Drilling Technology in Nontechnical Language Second Edition






                  Logging the hole

                  The same logs are used here as per the previous hole section. In addition,
              some  extra  logs  will  help  evaluate  the  reservoir  and  yield  information
              needed to design the well test program.
                  One tool that will almost certainly be run will place a probe against
              the formation and open up a sample chamber on the inside of the tool.
              This can take a sample of formation fluids at the composition that is down

              hole for analysis at the surface. These tools can also take very accurate
              pressure readings and can measure the formation permeability at the
              wellbore face.



                  Running and cementing the production liner

                  A liner, being effectively a string of casing with the top half missing, is
              assembled and then run in the hole below a string of drill pipe. At the top
              of the liner is a liner hanger, which may be hydraulically or mechanically
              manipulated to move hardened steel elements out to grip the inside of the
              previous casing. Cement is pumped down the drillstring, with special plugs
              to separate the fluids. Once the cement is in place outside the liner, the drill

              pipe is released from the liner hanger and pulled back to the surface.


                            Production Testing the Well

                  The cuttings samples, logs, and core samples show that there is gas and
              that there is likely to be a commercially worthwhile amount of oil. There

              exists sufficient permeability for hydrocarbons to be produced into the
              wellbore. The inside of the well needs to be cleaned out, a string of tubing
              run in the well, holes made through the liner into the reservoir (called
              perforating), and the well must flow to test the reservoir’s characteristics.


                  Preparing the well for the test string


                  The inside of the well contains drilling fluid that has a high level of
              solid materials suspended in it. These solids may be part of the mud system,
              drilled solids, rust products from the steel in the well, and other debris. If







         _Devereux_Book.indb   80                                                  1/16/12   2:07 PM
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