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MWD and LWD: A Comparison

October 14th, 2019   |  5 min. read
MWD and LWD: A Comparison Blog Feature

When it comes to any form of offshore or depth drilling, safety and efficiency should be two considerations of paramount importance. Over the years, technological advances have made it possible for companies in the oil and gas industry to provide secure and comfortable accommodations for their drill operators. Moreover, enhanced drill bore capabilities have paved the way for companies to utilize more efficient directional drilling techniques.

Two important processes that can greatly contribute to an optimized drilling operation are MWD and LWD. This article will discuss what these two processes involve, as well as how they differ from each other. It will also briefly discuss why zoned accommodation cabins are so important to the success of any drilling operation, and how you can effectively source such cabins.

What is MWD?

MWD stands for measurement while drilling. It is a type of well logging originally designed in the 1980's to overcome the inherent challenges of well drilling at extreme angles (60 degrees from center or more). In MWD, measurement tools are directly incorporated into the drill string in order to provide real-time information for optimized drill steering.

MWD includes measurements of physical properties such as:

  • Temperature
  • Pressure
  • Wellbore trajectory

The MWD process can provide accurate readings on borehole inclination and azimuth. (An azimuth is defined as: "[A] horizontal direction expressed as the angular distance between the direction of a fixed point (such as the observer's heading) and the direction of the object.") All of these measurements are captured downhole, and then transmitted to the surface for the operator to monitor.

What is LWD?

The acronym LWD stands for logging while drilling. In this context, "logging" refers to the act of recording, storing, and transmitting information. It involves the methodology of transporting logging tools to the wellbore as an integral part of bottom hole assembly. LWD is an excellent way to acquire formation evaluation data, such as pore pressure estimates and mud weight, which can help operators to gain deeper insight into the nature of the reservoir, and ultimately make wiser, more efficient drilling decisions.

Originally developed and implemented in the early 1970's, LWD is an innovative and constantly improving technology that can potentially increase a well's production value, and significantly reduce construction costs. There are several variations of LWD, including:

  • Electromagnetic drilling
  • Nuclear logging
  • Acoustic logging
  • Nuclear magnetic resonance logging

LWD is a key component in the thorough analysis of a reservoir, and is highly useful for:

  • Geosteering
  • Geomechanical analysis
  • Petrophysical analysis
  • Reservoir fluid analysis and characterization
  • Reservoir mapping

What are the Differences Between MWD and LWD?

While MWD can be classified as a type of LWD, there are at least a couple of significant differences between these two techniques.

Speed of Transmission

The first big difference between MWD and LWD is the speed at which operators can retrieve stored data. MWD provides real-time data (RT) to drill operators, allowing them to constantly monitor the drilling operation and make relatively quick adjustments as needed.

In contrast, LWD refers to a methodology in which information is saved to a data capture tool and stored within solid state memory for some time. Then, once the data has been transmitted to the surface, the analyst on duty must perform an "information dump" to retrieve and decode all the recorded data for further examination.

Level of Detail

The other significant variation between MWD and LWD involves the level of detail each technique provides. MWD typically focuses on directional information, such as the inclination of the well and the azimuth. On the other hand, LWD provides many more details on the target formation, such as:

  • Gamma ray levels
  • Resistivity 
  • Porosity
  • Slowness (from sonic logs)
  • Internal and annular pressure
  • Vibration levels

Certain LWD tools are even designed to collect fluid samples from a recently drilled well section for more accurate reservoir analysis.

In summary, MWD offers real-time information transmission to drill operators, and is largely centered around direction-oriented data capture. LWD provides previously recorded data for analysis after an information dump, and generally gives much more detail.

The Importance of Properly Zoned Modules

In almost any operational environment that involves offshore drilling, MWD, or LWD processes, there are strict regulations in place with regards to worker accommodations. To ensure that workers remain safe, both on-duty and off, zoned cabins must meet stringent guidelines for secure accommodations and industrial spaces under hazardous conditions.

For instance, at Specialist Services RedGuard our portable accommodation modules (PAMs) and zoned modules are constructed in accord with IMO Safety of Life at Sea (SOLAS). Moreover, our design and fabrication processes include design, review, and certification by other key guidelines, such as ABS (American Bureaus of Shipping), Det Norske Veritas (DNV), United States Coast Guard (USCG) and Maritime Labour Convention (MLC) statutes.

Many portable accommodation and industrial modules are built for use in Zone 1 or Zone 2 hazardous areas. These two zones are classified as follows:

  • Zone 1 refers to environments in which "ignitable concentrations of flammable gases or vapors... are likely to occur under normal operating conditions."
  • Zone 2 refers to environments in which such ignitable concentrations are not likely to occur under normal conditions, but if they do occur, will persist for only a short period of time.

At Specialist Services RedGuard, we have a wealth of experience and knowledge in providing safe and highly customized accommodation solutions to our clients in the offshore drilling industry. Our zoned modules come in a wide variety of configurations and dimensions in order to fit various operations, weight restrictions, and space limitations. Our zoned units include ATEX certification (European Hazardous Area) as well as IECEx (International version) for global standards.

If you'd like to learn more about the products that we offer, and the benefits of partnering with us, reach out to us at Specialist Services RedGuard today for further information.

 

Specialist Services RedGuard Sales & Marketing

Specialist Services RedGuard Sales & Marketing

The Specialist Services RedGuard sales and marketing team curates and writes on a variety of topics regarding offshore modular buildings, technical buildings and accommodation modules, as well as service, maintenance, and parts. To inquire about any of the topics you read about on our blog, connect with us.

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