Lesson 1 Syllabus.ppt

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Underbalanced Drilling(UBD)

Lesson 1

Introduction

Chapter 1

Harold Vance Department of Petroleum Engineering



Introduction

Course Syllabus

Texts




Introduction


What is UBD Why Drill Underbalanced

Techniques and Limitations

Historical Perspectives



Course Description


This course provides an introduction and

application of techniques that can beutilized in underbalanced drilling. It willcover topics such as BOP equipment, the

types of drilling fluids used (air, mistfoam, etc.), flow drilling, and mud capdrilling.



Text


“Underbalanced Drilling Manual”

Gas Research Institute, GRI,Chicago, 1997.



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.



Instructor Dr. Jerome J. Schubert, PE, CPA

Phone: 979/862-1195

Office: Richardson Rm 501K

e-mail: [email protected]




What is UBD

Wellbore pressures “intentionally”maintained below formation pressurein the open hole section.

Formation fluids flow into the well.




Additional Definitions

Flow (Live) operations.

Operations intentionally undertakenwith a liquid drilling fluid systemwhere the hydrostatic pressure

exerted by the liquid column is belowformation pore pressure such that theformation fluid is allowed to flow tothe surface during the operations.




Additional Definitions, con’t Gasified Fluid Operations.

(Aerated Fluid Operated).

Operations intentionallyundertaken with a two-phasedrilling fluid containing someform of gas mixed with a liquidphase.

Gasified fluids normally do notcontain a surfactant.




Additional Definitions, con’t Foam Operations:

Operations intentionallyundertaken with a two-phasedrilling fluid containing someform of gas mixed with a

liquid phase and tied togetherwith a surfactant.

The liquid is the continuousphase.




Additional Definitions, con’t


Mist Operations:

Intentionally drilling with atwo-phase fluid having a gas

as the continuous phase.

The liquid in this fluidsystem is suspended in themixture as droplets.



Additional Definitions, con’t Air Operations:

Intentionally drilling using apure gas as the drilling fluid.

The gas can be air, nitrogen,natural gas, or any

combination of gases.




Additional Definitions, con’t Mudcap Operations:

Operations undertaken when the annular

pressure during flow drilling exceeds thesafe pressure limit of the rotating controlelement.

Mudcap operations are not UB operation,but often are a result of drillingunderbalanced and employ many of thesame techniques and equipment.




Additional Definitions, con’t Snubbing Operations:

An intentional operation that

employs either a snubbing unit orcoiled-tubing unit in order tooperate at surface pressures that

exceed the limits of rotatingcontrol elements such as rotatingheads or rotating blowoutpreventers.




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 surfacepressure, without the requirementthat the well be “killed” prior toentering the wellbore.




Why drill underbalanced?

Increased Penetration Rate.

Increased Bit Life.

Minimized Lost Circulation.

Minimize Differential Sticking.




Why drill underbalanced?

Reduced Formation Damage.

Earlier Production.

Reduced Stimulation Requirements.

Improved Formation Evaluation. Environmental Benefits.




Historical perspectives

UBD operations are as old as the

drilling industry:

First wells were drilled with cabletool.

Cable tool drilling wasunderbalanced.





In 1866 a patent for air drilling

was issued.

First recorded use of a gasifiedfluid was in West Texas in 1932.





In 1938 mist was used by

The Texas Company to drill inCalifornia.

Natural gas was continuous

phase and oil was the liquidphase.





Interest dropped off using gas as

a drilling fluid until the 1950’swere it showed a resurgence in:

Canada.

West and Central Texas.Utah.

San Juan Basin of New Mexico.






Typical of Nat Gas operations in New Mexico





Early Air Compressors used in air drilling



HistoricalPerspectives


Natural Gasdrilling in

West Texas.





In the 1960’s, the

U.S. Atomic

Energy

Commission

began to study the

use of foams toclean wellbores as

large as 60” in

diameter from 45

feet as 2000 feet.




Until the mid 1980’s UBD was just a niche industry, and onlyutilized in certain areasaround the world.





Mid 1980’s Horizontal DrillingBecame Fairly Common (Plot

is for three companies)

Year

N o . o f W

e l l s




Mid 1980’s Horizontal Drilling

Became Fairly Common (Plot is

for three companies)

Year

T o t a l

L i g h t w e i g h t

F l u i d W e l l s Growth in Horizontal Drilling

Spurred the Resurgence in UBD(US operations)



Until 1987 the maximumworking pressure rating of

rotating heads was 150-300psi.

RBOP was developed with aworking pressure of 1000 psi.





Rotating Control Devices

RBOP-1000 psi (1987) PCWD-3000 psi (1995) RCH-2500 psi (1995)



Closed Loop System Allows re-use of the drilling fluids in foam

systems environmentally friendly.




Nitrogen

Generation System




Electromagnetic

MWD Tools




Hollow Glass Spheres




Factors Leading

to Increased UBD Horizontal Drilling.

Closed Systems. High-Pressure Rotating Control

Devices.

Electromagnetic MWD Systems.

HP HV Compressors.




Factors Leading

to Increased UBD


Increased Availability of Nitrogen.

Better Reservoir and Rock Strength Analysis.

Improved Hydraulics Analysis.

Percussion Tools.

Ability to Re-Circulate Fluids.






PETE 689

Underbalanced Drilling(UBD)

Documents

Lesson 1 Syllabus.ppt