Page 242 - Shale Shakers Drilling Fluid Systems
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APPENDI                     X     A




                          Derrick/nan's Pages













          This appendix contains comments and guide-            • High mud costs
        lines directed specifically toward rig hands that       • Pump wear
        control shale shaker operations. In so far as pos-      • Short bit life
        sible, this section will be written in the language   Good shaker operation helps prevent these.
        of the rig crew (without some of the more color-
        ful adjectives not used in polite society but com-
        monly used on a rig.) Effective use of shale shak-          SHALE SHAKER OPERATIONS
        ers is greatly dependent upon the treatment that
        they receive by the hands on the rig.                   Shakers now come in a dazzling assortment of
          If some basic rules are not followed, however,      sizes, shapes, and motions. Their performance is
        all of the theory in the world will not help drill a  controlled by the size and shape of the openings in
        well. This appendix does not present anything new     the screen, the movement of the screen, the mud
        but it does summarize practical operating guide-      properties, and the type of cuttings arriving at the
        lines. First, the shale shaker purpose is described;  shaker. The one selected for your rig may or may
        and second, some operating rules are discussed. In    not be the best one for the job. Unfortunately, if it
        other sections this manual describes shale shakers,   is not, it must still be kept operational and with hard
        screens, types of motion, and much other informa-     work perhaps it can be made to do the job. All com-
        tion. In this section, practical rules are discussed.  mercial shakers, however will remove cuttings—and
                                                              they do a better job if they are properly treated.
                                                                If the mud is not bringing cuttings to the sur-
                          PURPOSE                             face, the screen cannot remove them. The solids
                                                              coming off the end of the shaker screen should
          The purpose of a shale shaker is to remove          have sharp edges. Cuttings that roll around in the
        from the mud "dirt" or rock drilled by the bit. The   borehole on the way to the surface have rounded
        shale shaker is the first piece of solids control     edges. Rounded edges or round cuttings indicates
        equipment to treat or condition the drilling fluid.   that the mud is not bringing cuttings to the sur-
        Good shaker performance is necessary if the en-       face as fast as it should. The mud engineer, or
        tire system is to work properly.                      driller, should be told that the cuttings are not
          A carpenter's drill bit carries wood cuttings out   reaching the shaker.
        of a drilled hole with the spirals on the bit itself.   If the cuttings are arriving at the shale shaker,
        In oil or gas drilling the drill string does not have  several general rules will make certain that the
        the spirals to move the cuttings out of the hole.     shaker is working properly.
        In a well, mud brings the cuttings to the surface.
        These cuttings must be taken out of the mud.             1. The shale shaker should be run continuously
        Many bad things can happen on a rig if these               while circulating. Cuttings cannot be removed
        cuttings are not removed from the drilling fluid.          if the shaker is not in motion.
          Cuttings, or drilled solids, left in the mud, cre-    2. The mud should cover most of the screen. If
        ate many problems. Some of these problems are:             the mud covers only \ or ^ of the screen,
                                                                   the screen mesh is too coarse.
          • Stuck pipe                                          3. A screen with a hole in it should be replaced
          • Bad cement jobs                                        immediately. The hole in a panel screen can
          • Lost circulation                                       be plugged. Cuttings are not removed from
          • Slow drilling rates                                    the mud flowing through the hole.

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