Page 91 - Drilling Technology in Nontechnical Language
P. 91

82              Drilling Technology in Nontechnical Language Second Edition






              the environmental disaster that he wanted and obtained. As it was, SSSVs
              unfortunately were not used.
                  The tubing is suspended in the well at the wellhead, just as the casings
              were suspended at surface. After running the last string of casing, the
              BOP was removed, and a tubing head spool placed on the wellhead. This
              goes on top of the casing spool in the same way that the casing spool went
              on top of the casinghead housing. With the complete tubing string in the
              well, a tubing hanger is screwed on top of the tubing, and this lands inside
              the tubing head spool. Special bolts in the spool are screwed in to lock the
              tubing hanger in place. After pressure testing to make sure the seals all
              work, the BOP is removed, and a special assembly of valves, called the
              Christmas tree, is bolted on top of the tubing head spool.
                  Now the well is ready to perforate. In preparation for perforating, a
              special BOP is placed on top of the Christmas tree, which will allow the
              well to be perforated with wireline while having the possibility to seal
              around the wireline.



                  Perforating the well

                  The logging cable is now used to run perforating guns inside the tubing.
              A perforating gun consists of some sort of carrier mechanism, inside of
              which is a set of shaped explosive charges. These are run in the well so
              that they are opposite the reservoir. When they are detonated, the shaped
              charge efficiently focuses the explosive energy in a narrow path outwards.

              This punctures the liner and creates a tunnel through the rock, often up to
              22" (559 mm) in length.



                  Testing the well

                  Well testing is discussed in more detail in chapter 10, “Evaluation.”
                  The hydrocarbons produced during testing are normally burned off.

              There is nowhere that the fluids can be safely stored, and in the case of this
              exploration well in the desert, no infrastructure exists that could capture
              the produced oil and get it to a refinery.











         _Devereux_Book.indb   82                                                  1/16/12   2:07 PM
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