MUD RHEOLOGY

Rheology is the study of

how matter deforms and flows

VISCOSITY

Resistance to flow of a fluid

FUNNEL VISCOSITY

100 centipoise (cp) = 1 poise
Centipoise is the dimension used to express:
Plastic viscosity
Apparent viscosity
Effective viscosity

The dimensions of lb/100 sq ft are used for expressing:

-Yield point
- Initial gel
- 10-minute gel

SHEAR STRESS

Internal force that resists flow
System pressure loss (circulating pressure on the rig)
Simulated by the dial reading on a V G meter

SHEAR RATE

The velocity at which one layer of fluid moves past another

The bulk (average) velocity at which a fluid is moving
Annular velocity in the circulating system is an example of bulk velocity
Velocity is the RPM on a V G meter

Viscosity

Factors Influenced by Mud Rheology

Hole cleaning
Suspension of solids
Hole stability
Solids control
Equivalent circulating densities
Surge / swab pressures

Measurement - Rotational Viscometer

Effect of Temperature & Pressure

Temperature reduces viscosity
Pressure increases viscosity
High temperature

Breakdown of polymers
Gelation of solids
Plastic Viscosity
- Resistance to flow due to mechanical frictio
- Affected by:
1. Solids concentration
2. Size and shape of the solids
3. Viscosity of the fluid phase
Plastic Viscosity Increased by:

Hydratable Drill Solids

Clays, shales

Inert Drill Solids

Sand, limestone, etc.

Colloidal Matter

Starch, CMC

Particles breaking, thus increasing surface area and more friction

Weight material to increase density
Area Increase by Breaking of Solids

Effect of Particle Size on Viscosity

Plastic Viscosity Decreased by
Removal of Solids
Shale shaker
Desanders, desilters, and centrifuges
Lowering of gel strength allows larger particles to settle out
Dilution of solids with water
How Solids Affect Mud Viscosity

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Basic Petroleum Geology and Log Analysis

Geology is the science that deals with the history and structure of the earth and its life
forms, especially as recorded in the rock record. A basic understanding of its concepts
and processes is essential in the petroleum industry, for it is used to predict where oil
accumulations might occur. It is the job of the petroleum geologist to use his/her
knowledge to reconstruct the geologic history of an area to determine whether the
formations are likely to contain petroleum reservoirs. It is also the job of the geologist to
determine whether the recovery and production of these hydrocarbons will be
commercially profitable.
The physical characteristics of a reservoir, how petroleum originated and in what type of
rock, what types of fluids exist in the reservoir, how hydrocarbons become trapped, and
basic well log analysis are some of the concepts vital to the production and recovery
efforts of any exploration or energy service company.oil spill

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Carl Gatlin - Drilling Well Completion

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METHODS OF DEFLECTING A WELLBORE con't 3

Downhole Motor

Turbodrills have been around for many years but are seldom used for directional drilling

Turbodrills have very high rotary speeds (500 to 1200 rpm)

Because of the high rpm, bit life is limited
Diamond and PDC bits are more applicable to turbodrills
Turbodrills have low starting torque
If the motor is in a bind, it is hard to get the motor started
Turbodrills are used in directional drilling where the temperature exceeds the limit of a positive displacement motor

Positive displacement motors were introduced in the 1960’s

Rotor/stator configuration

Speed (RPM) / Torque (Ft-Lbs.)

For best performance, the power section should be matched to the bit and formation being drilled. The speed and torque of a power section is directly linked to the number of lobes on the rotor and stator. The higher the number of lobes, the higher the torque and the lower the RPM.

Dump sub

Not often used
Allows string to fill or drain when tripping
Allows low volume circulation in stuck bit situations

Power pack section

Rotor is hard

Stator is flexible

Stator housing is thin

PDM is not a drill collar

Reverse application of the Moineau pump principle
Elastomer lined - steel tube stator
Chrome coated steel rotor
Converts Hydraulic HP (flow & pressure) to Mechanical HP (rpm & torque) There are three main producers of motor power sections in the world:

Typical PDM power curve

Rotor is coupled to transmission
Transmission shaft is coupled to the bearing pack
The adjustable bent housing enables the bend to be changed at the wellsite
The housing can be adjusted 0.26 to 3.0 degrees depending upon motor size

Bearing function

On bottom thrust bearings carry force from the bit (WOB)
Off bottom thrust bearings carry the hydraulic load of the mud and weight of the rotor
Radial bearings carry side loads
Flow restrictor diverts a portion of the mud for lubrication

METHODS OF DEFLECTING A WELLBORE

METHODS OF DEFLECTING A WELLBORE con't

METHODS OF DEFLECTING A WELLBORE con't 2

METHODS OF DEFLECTING A WELLBORE con't 4

Advanced Reservoir Engineering

Advanced
Reservoir
Engineering

Tarek Ahmed
Senior Staff Advisor
Anadarko Petroleum Corporation
Paul D. McKinney
V.P. Reservoir Engineering
Anadarko Canada Corporation

Dedication

This book is dedicated to our wonderful and understanding wives, Shanna Ahmed and Teresa McKinney, (without whom this
book would have been finished a year ago), and to our beautiful children (NINE of them, wow), Jennifer (the 16 year old
nightmare), Justin, Brittany and Carsen Ahmed, and Allison, Sophie, Garretson, Noah and Isabelle McKinney.

The primary focus of this book is to present the basic
physics of reservoir engineering using the simplest and
most straightforward of mathematical techniques. It is only
through having a complete understanding of physics of
reservoir engineering that the engineer can hope to solve
complex reservoir problems in a practical manner. The book
is arranged so that it can be used as a textbook for senior
and graduate students or as a reference book for practicing
engineers.
Chapter 1 describes the theory and practice of well testing
and pressure analysis techniques, which is probably one
of the most important subjects in reservoir engineering.
Chapter 2 discusses various water-influx models along with
detailed descriptions of the computational steps involved in
applying these models. Chapter 3 presents the mathematical
treatment of unconventional gas reservoirs that include
abnormally-pressured reservoirs, coalbed methane, tight
gas, gas hydrates, and shallow gas reservoirs. Chapter 4
covers the basic principle oil recovery mechanisms and the
various forms of the material balance equation. Chapter 5
focuses on illustrating the practical application of the MBE
in predicting the oil reservoir performance under different
scenarios of driving mechanisms. Fundamentals of oil field
economics are discussed in Chapter 6.

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Well Engineering & Construction

hussain rabia

Chapter 1 : Pore Pressure 1
Chapter 2 : Formation Integrity Tests 49
Chapter 3 : Kick Tolerance 71
Chapter 4 : Casing Properties 99
Chapter 5 : Casing Design Principles 143
Chapter 6 : Cementing 201
Chapter 7 : Drilling Fluids 265
Chapter 8 : Practical Rig Hydraulics 305
Chapter 9 : Drill Bits 339
Chapter 10 : Drillstring Design 383
Chapter 11 : Directional Drilling 439
Chapter 12 : Wellbore Stability 525
Chapter 13 : Hole Problems 569
Chapter 14 : Horizontal & Multilateral Wells 625
Chapter 15 : High Pressure & High Temperature Wells 675
Chapter 16 : Rig Components 711
Chapter 17 : Well Costing743

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METHODS OF DEFLECTING A WELLBORE con't 2

Rotary BHA

The rotary BHA consists of a bit, drill collars, stabilizers, reamers, subs and other special tools run below the drill pipe
Motors were used to put the wellbore on course and rotary BHA’s were used to drill the majority of the well
Even though rotary assemblies are used only occasionally, we will still look at them
Steerable motor assemblies in the rotating mode are still rotary BHA’s subject to the same influences as the rotary BHA
A slick assembly is simply a bit and drill collars

The deviation tendency is caused by the bending of the drill collars
The point at which the collars touch the wall of the hole is the tangency point
The resultant force applied to the formation is not in the direction of the hole axis but in the direction of the drill collar axis

The resultant force can be broken up into its components FB and FP

FB is the side force caused by the bending of the collars or building force
FP is the force due to gravity or pendulum force
Ideally, if

FP > FB, the hole inclination will drop
FP < FB, the hole inclination will increase
FP = FB, the hole inclination will remain constant

The building force can be increased by increasing bit weight, which drives the tangency point down
The building force is also affected by the stiffness of the collars
Stiffer collars will bend less
As the diameter of the collar increases, the stiffness of the collar increases

The pendulum force can be increased by reducing bit weight and using larger diameter collars
ØSome inclination is required to have a pendulum force
ØFor a slick assembly, the building and pendulum force will balance at relatively low inclinations; therefore, they are not expected to build much inclination

So why does the inclination exceed 1 to 2o in some areas while it does not in other areas?
If the bed dip is relatively flat, we seldom have any deviation problems
When bed dip is encountered, we can experience deviation problems in harder rock

Deviation problems are associated with formation dip
The anisotropy of the formation causes deviation

If the formation deviation tendency can be defined as a force FF, the resultant force at the bit would be
-FB + FP + FF
The wellbore will continue to build angle until the sum of the forces is equal to zero
Unfortunately it is difficult to define FF and it changes with depth

Rule of thumb

If the bed dip is less than 45 degrees, the bit will have a tendency to deviate perpendicular to the bed dip (up dip)
If bed dip is above 65 degrees, the bit will have a tendency to deviate along the bed dip
Between 45 and 65 degrees, the bit can do either
In directional drilling, it is the difference between the bit angle and the formation dip
The formation may want the bit to drop inclination when the wellbore is at an inclination greater than bed dip
The two forces associated with a rotary assembly are the building force (FB) and the dropping force (FP)
If we want to make a building assembly, the building force must be maximized
Stabilizers are used as fulcrums in order to increase the side force at the bit

Building assembly

A building assembly is constructed by placing a stabilizer near the bit
Bending of the drill collars above the stabilizer causes the building force at the bit to increase substantially

At low inclinations, the drill collars are bent by increasing bit weight

At higher inclinations, gravity will bend the collars and the build tendency is less affected by bit weight
In order to make a dropping assembly, the pendulum force is maximized by placing a stabilizer at least 30 to 90 feet above the bit

If the collars touch the wall of the hole between the stabilizer and the bit, the tangency point becomes the place where the collars first touch the wall of the hole
If the stabilizer is too far above the bit, the collars will touch the wall and the pendulum force will be reduced

-A holding assembly is constructed by placing stabilizers closer together so that the collars are more rigid
-Bit side force is minimized

Holding inclination is the most difficult with a rotary assembly

Analysis by Amoco indicated that

-Assembly A proved to be the most successful even though it maintained inclination only 60 percent of the time
-Assembly B maintained inclination less than 50 percent of the time
-Assembly C held inclination less than 50% of the time

To better understand the forces on a rotary BHA, lets look at a single stabilizer assembly with the stabilizer positioned at various distances from the bit

Rotary BHA’s were not very efficient as it was difficult to predict the actual performance of any rotary BHA
Frequent trips were required to change stabilizer placement and size

The build, hold or drop tendency of the rotary BHA could be adjusted but the walk tendency could not be changed substantially

A pure rotary assembly is used only occasionally today
Derivatives of the rotary assembly are used frequently
Steerable motor assembly
Rotary steerable assembly

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US sues BP, 8 other companies in Gulf oil spill Gulf oil spill recovery exec dead in plane crash Ex-CEO says BP was unprepared for oil spill BP's oil spill costs grow Scientists to see if oil spill hurt deep sea life Depression soars among Gulf residents after oil s

pill BP spent $93M on advertising after Gulf oil spill