Editing Methane clathrate (section)

===Effect of hydrate phase transition during deep water drilling===
When drilling in oil- and gas-bearing formations submerged in deep water, the reservoir gas may flow into the well bore and form gas hydrates owing to the low temperatures and high pressures found during deep water drilling. The gas hydrates may then flow upward with drilling mud or other discharged fluids. When the hydrates rise, the pressure in the [[Annulus (oil well)|annulus]] decreases and the hydrates dissociate into gas and water. The rapid gas expansion ejects fluid from the well, reducing the pressure further, which leads to more hydrate dissociation and further fluid ejection. The resulting violent expulsion of fluid from the annulus is one potential cause or contributor to the "kick".<ref name=Wang>{{Cite journal |last=Wang |first=Zhiyuan |author2=Sun Baojiang |title=Annular multiphase flow behavior during deep water drilling and the effect of hydrate phase transition |journal=Petroleum Science |volume=6 |pages=57–63 |year=2009 |issue=1 |doi=10.1007/s12182-009-0010-3 |bibcode=2009PetSc...6...57W |doi-access=free}}</ref> (Kicks, which can cause blowouts, typically do not involve hydrates: see [[Blowout (well drilling)#Formation kick|Blowout: formation kick]]).

Measures which reduce the risk of hydrate formation include:
* High flow-rates, which limit the time for hydrate formation in a volume of fluid, thereby reducing the kick potential.<ref name=Wang/>
* Careful measuring of line flow to detect incipient hydrate plugging.<ref name=Wang/>
* Additional care in measuring when gas production rates are low and the possibility of hydrate formation is higher than at relatively high gas flow rates.<ref name=Wang/>
* Monitoring of [[Casing (borehole)|well casing]] after it is "[[Shut-in (oil drilling)|shut in]]" (isolated) may indicate hydrate formation. Following "shut in", the pressure rises while gas diffuses through the reservoir to the [[bore hole]]; the rate of pressure rise exhibit a reduced rate of increase while hydrates are forming.<ref name=Wang/>
* Additions of energy (e.g., the energy released by [[Casing (borehole)#Cementing|setting cement]] used in well completion) can raise the temperature and convert hydrates to gas, producing a "kick".