Horizontal wells are wells drilled horizontally within a productive formation rather than vertically. They have several advantages over vertical wells like improving productivity, draining a broader area, and accessing reserves that cannot be reached by vertical wells. Horizontal wells are classified based on their build rates into short, medium, and long radius. While they can improve recovery and reduce surface infrastructure compared to vertical wells, horizontal wells are more expensive to drill. Their higher costs also carry a greater risk of economic failure than vertical wells. Modern drilling now enables horizontal laterals of thousands of meters to further boost recovery.

2. • What is horizontal wells
• History of horizontal wells
• Classification of horizontal wells
• Application of horizontal wells
• Horizontal wells compare to vertical wells
• Horizontal well costs
• Economic failure in horizontal wells
• Future of horizontal wells

3. By oilfield convention, a
horizontal well is defined as
a well with an inclination
angle of 90 degrees from
the vertical. A vertical well
is one with zero inclination
angle.

4. • Some of the early horizontal well efforts
date back to 1930.
• In the late 70’s and early 80’s, with
oil prices around $35 a barrel,
interest in horizontal wells was
reignited.

5. The purpose of the horizontal wells was to:
• enhance well productivity,
• reduce water and gas coning,
• intersect natural fractures and to
• improve well economics.

6. 1. Short-Radius
2. Medium-Radius
3. Long-Radius
Horizontal wells are normally
characterized by their buildup
rates and are broadly classified
into three groups:

7. The table below illustrated
classification of horizontal wells
according to their Build Rate.

8. A) Hit targets that cannot be reached
by vertical drilling.
B) Drain a broad area from a single
drilling pad.
C) Increase the length of the "pay
zone" within the target rock unit.

9. D) Improve the productivity of wells in
a fractured reservoir.
E) Seal or relieve pressure in an "out-
of-control" well.
F) Install underground utilities where
excavation is not possible.

10. To produce the same amount
of oil, one needs fewer
horizontal wells as compared
to vertical wells. This results in
reduced need for surface
pipelines, locations, etc.

11. • Higher rates and reserves as compared
to vertical wells. This results in less
finding cost and less operating cost per
barrel of oil produced.
• vertical well operating costs are $7 to
$9 per barrel of oil, the horizontal well
operating costs are $3 to $4 per barrel.

12. • The costs of horizontal well
installation varies greatly depending
on many site-specific factors.
• with estimates from $5,000 to
$850,000 per well
• Price per foot estimates range from
$25 to $85 and per day from $1,500
to $15,000.

13. • Horizontal wells cost is
greater than vertical wells
about 2.5 to 3 times, so
you have a high risk of
economic failure.
• Eliminate the risk and drill
vertical wells.

14. Modern methods allow the
drilling of several thousand
meters of horizontal sections,
thereby increasing access to
the edges of the reservoir and
achieving higher recovery
with fewer wells.

16. • Petroleum Production Engineering, A Computer-Assisted
Approach by Boyun Guo, PH.D. , William C. Lyons, PH.D. and Ali
Ghalambor, PH.D.
• Horizontal Wells by Ralinda R. Miller, P.G.
• Cost/Benefits of Horizontal Wells by S. D. Joshi, SPE, Joshi
Technologies International.
• A Review of Horizontal Well Technology and Its Domestic
Applications by Diane W. Lique.
• Horizontal Wells-Subsurface Contaminats Focus Area
• http://www.fuelsnews.com/low-oil-decimates-rig-count-
producers-hold-hope/

17. • http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3866387/
• http://www.oges.info/3287/horizontal-well
• http://www.ogj.com/articles/print/volume-93/issue-
25/in-this-issue/pipeline/survey-shows-successes-
failures-of-horizontal-wells.html
• http://geology.com/articles/horizontal-drilling/