Mwd Sonny Class

MEASUREMENT WHILE DRILLING (MWD), LOGGING WHILE DRILLING (LWD) AND GEOSTEERING ADVANCED DRILLING ENGINEERING PAB4333

LEARNING OBJECTIVES Having worked through through this session the students will be able to: 1.

2.

Describe the benefits of using and the general principles behind the MWD, MWD, LWD and Geo-steering Geo-steer ing concept. Describe the applications applic ations of the MWD, MWD, LWD LWD and Geo-steering.

LEARNING CONTENTS 1. 2. 3. 4. 5. 6. 7. 8. 9.

Introduction Transmission System Power Source Sensors Directional Tools Gamma ray Tools Transmission and Control Systems Surface System Future Development

INTRODUCTION 

Concept

- Rea eall Time Time da data ta 

Application - Dire Direct ctio ionnal - Pet etrrophys ophysic ical al

- Drilli Drilling ng parame parameter terss

MWD CONFIGURATION

TOOLS CONFIGURATION 

SENSOR

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Rate of Penetration

DATA PRODUCED Drilling Rate, ft/Min or ft/hr

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Rotary or bit speed Mechanical Efficiency Log

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Sticking pipe indicator

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Strain gauge

Weight on Bit, Torque, Bending Moment

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Temperature

Bottom Hole Mud temperature

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Pressure

Bottom Hole Hydrostatic mud Pressure

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Gamma Ray

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Resistivity

Short Normal, Focused resistivity

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Conductivity

Induction, High-frequency Conductivity

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Neutron

Porosity Log

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Revolution per minutes (RPM) Monitor bit condition Monitors friction losses

Lithology Log

MWD AND LWD INSTRUMENT SPECIFICATIONS

TOOLS FEATURE

OPERATING PARAMETERS

LOGGING IN DIRECTIONAL WELL

Gamma Ray Directional System

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.

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:

TELEMETRY TECHNIQUES Pulses are sent to surface 

HARD WIRE

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ELECTROMAGNETIC

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ACCOUSTIC

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MUD PULSE TELEMETRY

TRANSMISSON SYSTEM 

POSITIVE MUD PULSE

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NEGATIVE MUD PULSE

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CONTINUES WAVE (SIREN) [FREQUENCY MODULATION]

TRANSMISSON SYSTEM 

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

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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.

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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.

TRANSMISSION TECHNIQEUS

POWER SOURCES

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.

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

:

Orientation of Sensors in Tool

Measuring Offset Toolface

The Locations of Sensors in The Inclinometer

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). •

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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 the sensor to stop any such interference. •

Accelerometer

Accelerometer

Magnetometer 

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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 calculated the azimuth.

Magnetometer

Calculation for Inclination, Toolface and Azimuth 

Inclination ( ) – The angle between C accelerometer and vertical. Looking at a vertical cross-section: Eq. – 1

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Toolface ( ) – the angle between high side and B accelerometer. Looking down the tool along the C axis:

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.

Calculation for Inclination, Toolface and Azimuth And substituting for a, b : Eq. - 3

Example Calculation 

The following data were obtained from the output of a MWD survey: Accelerometer Voltage:

Magnetometer Voltage

Ga = - 0.0132 Hx = 0.1062 Gb = 0.0157 Hy = 0.2510 Gc = 1.0141 Hz = 0.9206 The offset toolface = 0 and the magnetic declination = 7 W. From this data calculate: 1. Inclination, 2. Azimuth 3. Gravity Toolface

Accuracy of MWD Surveys 

Inclination : +/- 0.25

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Azimuth : +/- 1.50

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Toolface : +/- 3.00

Comparison of MWD and Wireline Log

Comparison of MWD and Wireline Log

LWD AND WIRELINE COMPARISON

WIRELINE LOG EXAMPLE

EXAMPLE LOGGING PROGRAM

EXAMPLE LOGGING PROGRAM

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. •

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1. http://chinookconsulting.ca/News/Remote-GeoSteering.html 2. http://www.makinhole.com/IMAGES/PDF/Stoner_  Technical%20Geosteering.pdf

Geosteering 

Data produced:

1.

Deviation

2.

Cutting, including HC shows and gas reading.

3.

4.

Transmission of LWD tools in real time, typically up/down GR, density, neutron and resistivity. Drilling parameters such as: Losses, Kick ROP, and torque.

Example of Up/Down Response as Borehole Crosses Boundary from Above

Example of Up/Down Response as Borehole Crosses Boundary from Above

Example of Up/Down Response as Borehole Crosses Boundary from Above

Example of Up/Down Response as Borehole Crosses Boundary from Above

Example of Up/Down Response as Borehole Crosses Boundary from Above

Four Scenario of Wellbore Leaving a Formation

Example of geosteered Well

Landing a Horizontal Well Using Geosteering

http://www.makinhole.com/IMAGES/PDF/Stoner_T

Example of Up/Down Response as Borehole Crosses Boundary from Above

Q & A

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.