MWD and LWD Acquisition(Measurement and Logging

While Drilling)

Petrophysical Data Acquisition Basics

Learning Objectives

By the end of this lesson, you will be able to:

Understand the concept of Measurements While Drilling (MWD) and the difference between MWD and LWD

Identify five or more typical MWD and LWD measurements, respectively

Understand the terminology used for the different events and sections of a directional drilling well path

Describe the downhole placement of the MWD and LWD sensors with respect to the bit

Logging While Drilling

Tool & Technology Development

Logging While Drilling Applications and Advantages:

• Petrophysics; formation evaluation while drilling, particularly highly deviated and horizontal wellbores. Measurements made early in Invasion process. Improved measurements due to longer sampling time (compare wireline).

• Well Placement: real time ability to change wellbore trajectories to reach target.

MWD & LWD Tools Have Different Uses

Measurement While Drilling (MWD) Tools Uses• Wellbore steering (direction and azimuth)• Drilling parameters (WOB, torque, pressure, • Correlation resistivity• Gamma ray

Logging While Drilling (LWD) Tools Uses• Real time logging of petrophysical parameters:

– Resistivity, Density, Neutron Porosity, Acoustic, NMR, Formation Imaging,

• LWD Density and GR have “azimuthal” capability,• Can include resistivity-at-bit (RAB)

Typical MWD Measurements

Torque Weight on Bit Borehole pressure Borehole Temperature Tool Face Angle Hole Deviation from

Vertical Hole Azimuth with respect

to Geographic Coordinates

GR

Directional Drilling and Logging

7

MWD Tool String

Tool & Technology Development

Key Technology developments in Well Logging:• Computer Processing 1960s• Nuclear logging refinements 1970s• NMR tools; established in 60s but several decades to refine. First

tool introduced by Numar (now Halliburton).• LWD evolved from MWD measurements initially Gamma and

Resistivity curve, now full suite of logs as for Wireline can be run on the pipe during the drilling process. Key driver has been highly deviated and horizontal wells.

• Early barrier was data transmission to surface; key advance was Mud Pulse Telemetry.

LWD Measurements Available

Resistivity – shallow and deep

Gamma ray Density Neutron Sonic Borehole imaging NMR Pressure Fluid Sampler

Dynamic Invasion Profile – Conceptual

Deep Reading Parallel to Bedding

Major interpretation issue in shale gas, horizontal completions!

MWD – LWD Summary

Real-time availability of drilling parameters, Real-time availability of petrophysical parameters, Resistivity, density, neutron, sonic and images comparable with

wireline measurements, Invasion-free formation resistivity at bit, Petrophysical interpretation principles applicable regardless of

the logging tool conveyance method.

Learning Objectives

Understand the concept of Measurements While Drilling (MWD) and the difference between MWD and LWD

Identify five or more typical MWD and LWD measurements, respectively

Understand the terminology used for the different events and sections of a directional drilling well path

Describe the downhole placement of the MWD and LWD sensors with respect to the bit