Page 56 - Primer on Enhanced Oil Recovery

Introduction to well technology 47

Figure 6.1 Main well elements.

The following terms are used in well construction:
casing a string of pipes running into the well, having permanent or temporary adhesion
to the well wall;
cement sheath concrete, which fills the space between the borehole wall and the
casing;
shoe element of bottom casing;
cased interval of the wellbore the interval along the axis of the well, in which its
walls are lined with a casing;
open hole the interval along the axis of the well, where there is no casing;
the output of the borehole from under the shoe distance from the shoe to the bottom
of the well.

The main well elements are shown on the Fig. 6.1. In many cases a well struc-
ture can be more complex

6.2 Well flushing and drilling fluids

Removal of drilled rock fragments from a well is one of the most important opera-
tions which is performed during drilling and it is carried out using drilling mud
(drilling liquid mixture). The drilling mud should:

clean the bottom hole of the drilled rock and bring the rock fragments to the surface;