ATMPETE 406 UBDATM

ATM ATM

PETE 406 - Underbalanced Drilling, UBD

Lesson 8

Introduction

Underbalanced Drilling Manual, UDM: Chapter 1

Harold Vance Department of Petroleum Engineering

ATMPETE 406 UBDATM

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Introduction

• What is UBD

• Why drill underbalanced

• Techniques and Limitations

• Historical perspectives

Harold Vance Department of Petroleum Engineering

ATMPETE 406 UBDATM

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Text

• “Underbalanced Drilling Manual”, Gas Research Institute, GRI, Chicago, 1997.– Can be purchased online from the SPE ($61.50

for members), IADC, and other Petroleum publishing companies

– May be able to get it at the TAMU bookstore

Harold Vance Department of Petroleum Engineering

ATMPETE 406 UBDATM

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References

“A project Management Approach To Underbalanced Operations”, Signa Engineering Corp., Houston, 1998.

“Mudlite Air/Mist/Foam Hydraulics Model”, Maurer Engineering Inc., Houston, 1988

Selected papers and texts

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ATMPETE 406 UBDATM

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What is UBD

• Wellbore pressures “intentionally” maintained below formation pressure in the open hole section.

• Formation fluids flow into the well.

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ATMPETE 406 UBDATM

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Additional Definitions

• Flow (Live) operations;– wellbore pressures maintained below formation

pressure and the well is intentionally allowed to flow during drilling or completion operations

Harold Vance Department of Petroleum Engineering

ATMPETE 406 UBDATM

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Additional Definitions, con’t

• Gasified Fluid Operations (aerated fluid operated)– Operations intentionally undertaken with a two-

phase drilling fluid containing some form of gas mixed with a liquid phase.

– Gasified fluids normally do not contain a surfactant

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ATMPETE 406 UBDATM

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Additional Definitions, con’t

• Foam Operations– Operations intentionally undertaken with a two-

phase drilling fluid containing some form of gas mixed with a liquid phase and tied together with a surfactant

– The liquid phase is continuous

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ATMPETE 406 UBDATM

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Additional Definitions, con’t

• Mist Operations– Intentionally drilling with a two-phase fluid

having a gas as the continuous phase– The liquid in this fluid system is suspended in

the mixture as droplets

Harold Vance Department of Petroleum Engineering

ATMPETE 406 UBDATM

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Additional Definitions, con’t

• Air Operations– Intentionally drilling using a pure gas as the

drilling fluid.– The gas can be air, nitrogen, natural gas, or any

combination of gases

Harold Vance Department of Petroleum Engineering

ATMPETE 406 UBDATM

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Additional Definitions, con’t

• Mudcap Operations– Operations undertaken when the annular

pressure during flow drilling exceeds the safe pressure limit of the rotating control element.

– Mudcap operations are not underbalanced operation, but often are a result of drilling underbalanced and employ many of the same techniques and equipment

Harold Vance Department of Petroleum Engineering

ATMPETE 406 UBDATM

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Additional Definitions, con’t

• Snubbing Operations– An intentional operation that employs either a

snubbing unit or coiled-tubing unit in order to operate at surface pressures that exceed the limits of rotating control elements such as rotating heads or rotating blowout preventers

Harold Vance Department of Petroleum Engineering

ATMPETE 406 UBDATM

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Additional Definitions, con’t

• Coiled-tubing drilling– Use of a continuous-spool of pipe to drill with

instead of the conventional jointed drillpipe. – CT units were originally designed to operate on

live wells with surface pressure, without the requirement that the well be “killed” prior to entering the wellbore.

Harold Vance Department of Petroleum Engineering

ATMPETE 406 UBDATM

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Historical perspectives

• UBD operations are as old as the drilling industry– First wells were drilled with cable tool– Cable tool drilling was underbalanced

Harold Vance Department of Petroleum Engineering

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Historical perspectives

• In 1866 a patent for air drilling was issued

• First recorded use of a gasified fluid was in West Texas in 1932

Harold Vance Department of Petroleum Engineering

ATMPETE 406 UBDATM

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Historical perspectives

• In 1938 mist was used by The Texas Company to drill in California. – Natural gas was continuous phase and oil was

the liquid phase

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ATMPETE 406 UBDATM

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Historical perspectives

• Interest dropped off using gas as a drilling fluid until the 1950’s in:– Canada– West and Central Texas– Utah– San Juan Basin of New Mexico

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ATMPETE 406 UBDATM

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Historical perspectives

Natural Gas drilling in West Texas

Harold Vance Department of Petroleum Engineering

ATMPETE 406 UBDATM

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Historical perspectives

Early Air Compressors used in air drilling

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ATMPETE 406 UBDATM

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Historical perspectives

In the 1960’s, the U.S. Atomic Energy Commission began to study the use of foams to clean wellbores as large as 60” in diameter

Harold Vance Department of Petroleum Engineering

ATMPETE 406 UBDATM

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Historical perspectives

• Until the mid 1980’s UBD was just a niche industry, and only utilized in certain areas around the world

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Historical perspectivesMid 1980’s Horizontal Drilling Became Fairly Common (Plot is for three companies)

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Growth in Horizontal Drilling spurred the resurgence in UBD (US operations)

Harold Vance Department of Petroleum Engineering

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Rotating control Devices

Until 1987 the maximum working pressure rating of rotating heads was was 150-300 psi.

RBOP was developed with a working pressure of 1000 psi

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More equipment development

• 1995 Varco-Shaffer introduced an RBOP with a rated to 3000 psi

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ATMPETE 406 UBDATM

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Closed loop systemAllows re-use of the drilling fluids in foam systems

environmentally friendly

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ATMPETE 406 UBDATM

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Nitrogen Generation

System

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ATMPETE 406 UBDATM

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Electromagnetic MWD Tools

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ATMPETE 406 UBDATM

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Hollow Glass Spheres

Harold Vance Department of Petroleum Engineering

ATMPETE 406 UBDATM

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Factors leading to increased UBD

• Horizontal drilling• Closed systems• High-pressure rotating

control devices• Electromagnetic

MWD systems• HP HV compressors

• Increased availability of Nitrogen

• Better reservoir and rock strength analysis

• Improved Hydraulics analysis

• Percussion tools• Ability to re-circulate

fluids

Harold Vance Department of Petroleum Engineering

ATMPETE 406 UBDATM

ATM ATM

Harold Vance Department of Petroleum Engineering

ATMPETE 406 UBDATM

ATM ATM