Underbalanced Drilling

By Nishant Kumar PanigrahiSE Petroleum EnggMaharashtra Institute Of TechnologyPune-38

04/08/2023

CONTENTSINTRODUCTIONCONVENTIONAL APPROACHUNDERBALANCED DRILLINGUNDERBALANCE GASES UNDERBALANCE TECHNIQUESADVANTAGESDISADVANTAGESREFERENCES

Nishant Kumar Panigrahi

04/08/2023

IntroductionThe International association of Drilling

Contractors(IADC) defines Managed pressure Drilling as “an adaptive drilling process used to precisely control the annular pressure profile throughout the wellbore. The objectives are to establish the down hole pressure environments limits and to manage the annular pressure profile accordingly”

Underbalanced drilling, or UBD, is a procedure used to drill oil and gas wells where the pressure in the wellbore is kept lower than the fluid pressure in the formation being drilled.

Nishant Kumar Panigrahi

04/08/2023

Conventional approachIn the conventional approach, bottom hole

pressure is managed by controlling the density of the drilling fluid to maintain well bore pressure profile above the pore pressure at all times

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Introduction to underbalanced drilling

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Underbalance Gases

They Include air, nitrogen and natural gases Although not typical the natural gas from the well

can be re injected into the well to establish underbalance resulting in the most cost effective solution for underbalance drilling

Nitrogen is commonly preferred for its low cost of generation, scale of control and minimal potential for downhole fires. While pure nitrogen can be purchased, it is cost-prohibitive. Therefore, nitrogen is more commonly produced onsite with a membrane unit, resulting in a 95% level of purity.

Nishant Kumar Panigrahi

04/08/2023

Underbalance TechniquesThere are Four Main Techniques Use Of Light Weight Drilling Fluids Injection of gas down the drill pipeGas injection by parasite stringUse Of Nitrogen Foam

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AdvantagesPotential reduction in invasive formation damageMinimize the potential for lost circulationMinimize the potential for differential stickingEliminate need for costly mud systems and costlyDisposal of exotic muds Improved ROP on drilling, reducing drilling costs and increased bit lifeMitigation of extensive and expensive completion and stimulation operationsRapid indication of productive zones of the reservoir during drillingPotential economic benefit from flush production during drillingPotential to flow test while drilling

Nishant Kumar Panigrahi

04/08/2023

DisadvantagesUnderbalanced drilling is usually more

expensive than conventional drilling, and has safety issues of its own

This is true when combustible and corrosive gasses like processed flue gas and oxygen are injected into the drilling mud to lower its density.

Drilling underbalanced may be pointless from a formation damage standpoint if the underbalanced condition can not be maintained.

Underbalanced drilling also increases the chances of the wellbore collapsing in on itself

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References

Nishant Kumar Panigrahi

www.spe.orgwww.wikipedia.comwww.shell.comUNDERBALANCED DRILLING TECHNOLOGY -D.

Brant Bennion, Hycal Energy Research Laboratories Ltd.

04/08/2023

THANK YOU

Nishant Kumar Panigrahi