Hi MICK Z See...

Hi MICK Z See (http://geology.utah.gov/emp/pump/pdf/pumprpt13.pdf) extract below

Horizontal Drilling
Introduction
Three factors create reservoir heterogeneity within productive zones in the Leadville
Limestone: (1) variations in carbonate fabrics and facies, (2) diagenesis (including karstification
and various stages of dolomitization), and (3) fracturing. The extent of these factors and how
they are combined affect the degree to which they create barriers to fluid flow. Untested
compartments created by these conditions may be ideally suited for, as yet to be attempted,
horizontal drilling techniques.
Horizontal drilling, developed primarily in the 1990s, is now a common, economical
technique to increase oil production and reserves. Advances in downhole motors, flexible drill
pipe, and measurement-while-drilling (MWD) technology have resulted in improved success
and reduced drilling costs. Drilling horizontally (1) improves well/reservoir productivity, (2)
increases well drainage area and reservoir exposure, particularly critical if the reservoir is
fractured or thin (figure 10A, B, and C), (3) delays interface breakthrough (coning) (figure
10D), (4) improves sweep efficiency/ultimate recovery, (5) accelerates well payoff and rate of
return, (6) reduces inertial (turbulence) pressure losses, (7) accesses remote and isolated zones,
(8) improves reservoir characterization, and (9) exploits gravity drainage mechanism effectively
(Kikani, 1993; Stark, 2003).
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Figure 10. Reservoir conditions favorable for horizontal
drilling (modified from Kikani, 1993).
A
B
C
D
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