Mwd Sonny Class

52 

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MEASUREMENT WHILE

MEASUREMENT WHILE

DRILLING (MWD), LOGGING

DRILLING (MWD), LOGGING

WHILE DRILLING (LWD) AND

WHILE DRILLING (LWD) AND

GEOSTEERING

GEOSTEERING

ADVANCED DRILLING ENGINEERING

ADVANCED DRILLING ENGINEERING

PAB4333

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LEARNING OBJECTIVES

LEARNING OBJECTIVES

Having worked thro

Having worked through this session the students

ugh this session the students will be able to:

will be able to:

1.

1.

Describe the benefits of using and the general

Describe the benefits of using and the general

principles behind

principles behind the MWD

the MWD, LWD and Geo-steer

, LWD and Geo-steering

ing

concept.

concept.

2.

2.

Describe the applic

Describe the applications of

ations of the MWD

the MWD, LW

, LWD and

D and

Geo-steering.

Geo-steering.

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LEARNING CONTENTS

LEARNING CONTENTS

1.

1.

Introduction

Introduction

2.

2.

TTransmission

ransmission System

System

3.

3.

Power Source

Power Source

4.

4.

Sensors

Sensors

5.

5.

Directional Tools

Directional Tools

6.

6.

Gamma ray Tools

Gamma ray Tools

7.

7.

TTransmission and

ransmission and Control Systems

Control Systems

8.

8.

Surface System

Surface System

9.

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INTRODUCTION

INTRODUCTION

Concept

Concept

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Time

me da

data

ta

Application

Application

-- Di

Dire

rect

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-- P

Pet

etrroph

ophys

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ical

al

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MWD CONFIGURATION

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TOOLS CONFIGURATION

SENSOR

DATA

PRODUCED

 Rate of Penetration Drilling Rate, ft/Min or ft/hr  Rotary or bit speed Revolution per minutes (RPM)  Mechanical Efficiency Log Monitor bit condition

 Sticking pipe indicator Monitors friction losses

 Strain gauge Weight on Bit, Torque, Bending Moment  Temperature Bottom Hole Mud temperature

 Pressure Bottom Hole Hydrostatic mud Pressure

 Gamma Ray Lithology Log

 Resistivity Short Normal, Focused resistivity

 Conductivity Induction, High-frequency Conductivity

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MWD AND LWD INSTRUMENT

SPECIFICATIONS

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Pulser Unit

Receives stored data and converts it to high-frequency pressure pulse in the mud column, using mud pressure differentials between the inside and the outside drill collar.

Pressure pulse travel through the mud column to a sensitive pressure detector at the

surface.

Surface equipment includes a decoder to convert the

pressure pulse to electrical pulses and digital type displays and recorder.

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Pressure Differential of Mud Pulser

Large varieties of sensors have been developed for evaluation

of the data. A pressure transducer installed in stand pipe

receives the signal, whic is further decoded. The weight of a

drilling fluid plays an important role in mud pulse telemetry. To

calculate Pressure differential of mud pulser used:

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TELEMETRY TECHNIQUES

HARD WIRE

ELECTROMAGNETIC

ACCOUSTIC

MUD PULSE TELEMETRY

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TRANSMISSON SYSTEM

POSITIVE MUD PULSE

NEGATIVE MUD PULSE

CONTINUES WAVE (SIREN)

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TRANSMISSON SYSTEM

POSITIVE MUD PULSE

In the positive mud pulse system valve inside MWD tools partially closes, creating a temporary increase in standpipe pressure.

NEGATIVE MUD PULSE

In all system, fluid must be circulating through the drillstring. In the negative mud pulse system a valve inside the MWD tools opens and allows a small volume of mud to escape from the drillstring into the annulus. The opening and closing of this valve creates a small drop in standpipe pressure (50-100 psi), which can be detected by a transducer on surface.

MUD SIREN

A standing wave is set up in the mud column by a rotating slotted disc. The phase of this continuous wave can be reversed. The data is transmitted as a series of phase shifts.

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Directional Tools

All MWD use basically the same directional sensors for calculating Inclination, Azimuth and Tool face.

The sensor package consists of 3 orthogonal accelerometer and 3 orthogonal magnetometer.

Figure – A : Orientation of Sensors in Tool

C axis is aligned with the axis of tool, and B axis define the reference for the measuring toolface angle.

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Accelerometer

Measure the component of earth’s gravitational field along the

axis. A test mass is suspended from a quartz hinge which restricts

any movement to along one axis only (See Figure).

As the mass tends to move due to gravity acting along that axis, its

central position is maintained by an opposing electromagnetic

force. The larger the gravitational force, the larger pick-up current

required to oppose it.

Accelerometer can calculate the angle of inclination and tool face.

There must be enough non-magnetic drill collars above and below

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Magnetometer

A magnetometer is a instrument used to measure the strength

and/or direction of the magnetic field in the vicinity of the

instrument

The size of current is related to the direction of the coil with

respect to the direction of magnetic field.

As with the accelerometer the voltage is measured across a

resistor in the pick-up circuit of the magnetometer.

The voltage read each magnetometer can be used to

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Calculation for Inclination, Toolface and

Azimuth

Inclination ( )

 – 

The angle between C

accelerometer and vertical. Looking at a vertical

cross-section:

Toolface ( )

 – 

the angle between high side and B

accelerometer. Looking down the tool along the C

axis:

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Calculation for Inclination, Toolface and

Azimuth

Eq. - 2

Note : This gives the toolface of the MWD tool itself. To measure the toolface of the bent sub the offset angle must be included.

Azimuth ( ) - the angle between Z axis and magnetic North, when projected on to the horizontal plane. Looking in the horizontal plane we define 2 vectors V1 and V2 where V1 lies along tool axis.

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Calculation for Inclination, Toolface and

Azimuth

And substituting for a, b :

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Example Calculation

The following data were obtained from the output of a

MWD survey:

Accelerometer Voltage: Magnetometer Voltage

G

a

= - 0.0132

H

x

= 0.1062

G

b

= 0.0157

Hy = 0.2510

G

c

= 1.0141

H

z

= 0.9206

The offset toolface = 0 and the magnetic declination = 7 W.

From this data calculate:

1.

Inclination,

2.

Azimuth

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Accuracy of MWD Surveys

Inclination : +/- 0.25

Azimuth : +/- 1.50

Toolface : +/- 3.00

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Comparison of MWD and Wireline

Log

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Comparison of MWD and Wireline

Log

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Geosteering

• In the process of drilling a well, geosteering is the act of adjusting the borehole position

(inclination and azimuth angles) on the fly to reach one or more geological targets. These changes are based on geological information gathered while drilling.

• Used of information gained while drilling to make real time decision on the trajectory

of the well.

Geosteering is used in :

1. High-angle deviated wells in thin formations where productivity can be achieved only if the wellbore remains in a thin permeable zone.

2. Horizontal wells where it is necessary to remain a fixed distance from either a fluid contact or an overlying tight formation.

3. Closed proximity to a fault .

4. Drilling with a fixed orientation to a natural fracture.

1. http://chinookconsulting.ca/News/Remote-Geo-Steering.html

2. http://www.makinhole.com/IMAGES/PDF/Stoner_  Technical%20Geosteering.pdf

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Geosteering

Data produced:

1.

Deviation

2.

Cutting, including HC shows and gas reading.

3.

Transmission of LWD tools in real time, typically

up/down GR, density, neutron and resistivity.

4.

Drilling parameters such as: Losses, Kick ROP, and

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Example of Up/Down Response as Borehole Crosses

Boundary from Above

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Example of Up/Down Response as Borehole Crosses

Boundary from Above

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Example of Up/Down Response as Borehole Crosses

Boundary from Above

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Example of Up/Down Response as Borehole Crosses

Boundary from Above

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Example of Up/Down Response as

Borehole Crosses Boundary from Above

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Landing a Horizontal Well Using

Geosteering

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Example of Up/Down Response as

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Assignment (Due date 1 Sept 2010)

A. While drilling an 8 ½-in diameter hole at a deviation of

95 when the reservoir is existed. The offset between the up

and down reading is 2 m, with the up reading responding

first.

1.

What is the relative dip between the bore hole and

formation.

2.

If the direction of dip of the formation is the same as the

borehole, what is the absolute formation dip.

3.

Suppose that it is known that the formation dip azimuth is

at an angle of 40 to the borehole trajectory. What is now

the true formation dip.

Figure

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References

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Related subjects : MWD Mud-pulse System SperrySun