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Drilling problems include any difficulties encountered while drilling a well. The most common drilling problems are the creation of doglegs and key seats, hole instability, lost circulation, and excessive bottom hole temperatures.

Drilling problems include any difficulties encountered while [[drilling a well]]. The most common drilling problems are the creation of doglegs and key seats, hole instability, lost circulation, and excessive bottom hole temperatures.

==Doglegs==

==Doglegs==

* Overburden pressure

* Overburden pressure

* Earth movement forces

* Earth movement forces

* Pore pressure

* [http://www.glossary.oilfield.slb.com/en/Terms/p/pore_pressure.aspx Pore pressure]

* Water absorption, swelling, or dispersion

* Water absorption, swelling, or dispersion

* Ineffective hole cleaning

* Ineffective hole cleaning

* Stuck pipe

* Stuck pipe

* Bridges and fill-up

* [http://www.glossary.oilfield.slb.com/en/Terms/b/bridge.aspx Bridges] and fill-up

* Wellbore enlargement

* Wellbore enlargement

* Increased mud volume

* Increased mud volume

==Bottom hole temperatures==

==Bottom hole temperatures==

Extremely high bottom hole temperatures can occur in deep wellbores or in areas of abnormally high [http://www.glossary.oilfield.slb.com/en/Terms.aspx?LookIn=term%20name&filter=geothermal%20gradient geothermal gradient]. These excessively high bottom hole temperatures (greater than [[temperature::250°C]]) can cause drilling problems because of the accelerated thickening of water-based drilling fluids. The increase in viscosity and density of the drilling can may result in the following:

Extremely high bottom hole temperatures can occur in deep wellbores or in areas of abnormally high [[geothermal gradient]]. These excessively high bottom hole temperatures (greater than [[temperature::250°C]]) can cause drilling problems because of the accelerated thickening of [[Drilling_fluid#Water-based_muds|water-based drilling fluids]]. The increase in [[viscosity]] and density of the drilling can may result in the following:

* Reduction in penetration rates

* Reduction in penetration rates

* Lost circulation

* Lost circulation

* The well being swabbed when drill pipe is pulled

* The well being [http://www.glossary.oilfield.slb.com/en/Terms/s/swab.aspx swabbed] when drill pipe is pulled

* Stuck tools

* Stuck tools

This problem can be mitigated by using oil-based muds.

This problem can be mitigated by using [[Drilling_fluid#Oil-based_muds|oil-based muds]].

==See also==

==See also==

[[Category:Engineering]]

[[Category:Engineering]]

[[Category:Engineering – Development and Operations]]

[[Category:Engineering – Development and Operations]]