Measurement While DrillingMeasurement While DrillingAn OverviewAn Overview

Surveys are taken:– To permit calculation of well coordinates at a

series of measured depths, thus specifying well path and current bottom hole location

– To measure inclination and azimuth, hence well direction

– To determine orientation of tool face– To locate doglegs and allow calculation of dogleg

severity

Overview of SurveyingWhy Well bores are Surveyed

Accurate knowledge of the course of a well bore is necessary:– To avoid collision with other wells– To allow intersection by a relief well in the event

of a blowout– To hit the geological target areas– To provide a better definition of geological and

reservoir data to allow for optimization of production

Overview of SurveyingWhy Well bores are Surveyed

Overview of SurveyingData Gathering Techniques

Photographic film– Disks / strip

Memory modules– Multi-shot / MWD

Wire line– Surface readout

Mud Pulse Telemetry– MWD

Overview of SurveyingTechnology Tree

Survey

Magnetic

Low INC

SSMS

High INC

MSMWD

Gyroscopic

Low INC

Non SRG SRG

High INC

North Seeking

Inertial

SS = Single-Shot MS = Multi-ShotOR = Orientation ST = Steering Tool SRG = Surface Readout GyroMWD = Measurement While Drilling

Probe systems– Battery powered– 150°C (302°F)

Collar systems– Turbine powered– 125°C (257°F)– Large hole

Overview of SurveyingMWD

Overview of SurveyingCollar MWD

Function– Provide extremely reliable

borehole surveying and drillstring orientation, non-magnetic environments.

– Act as the platform for all gamma, dynamic, resistivity, and nuclear measurements

Limitations– Hot hole environments

MWD

Short Radius Motor

• Efficiency– Eliminate wireline– Compliment Drilling Systems

• Safety– No split bushings– BOP Operation– Continuous circulation

• Cost– Cost savings– Assist the overall drilling project

economics

GammaInterchangeable Sensor Modules

Directional

Overview of SurveyingMWD (Short Radius)