Logging while drilling - Advantages

Logging while drilling or LWD is a traditional term used to describe techniques and systems for collecting down-hole data while drilling. This is done without removing the drill pipe from the well.

Basically, LWD tools are massive, instrumented drill collars. In drilling, it is common practice to place the key tools closest to the bit. These LWD tools can go just about anywhere that the bit goes. The tools then transmit all information to the surface by using pulses into the mud or through signals that are superimposed on the drill pipe. This well-logging technique measures formation properties such as the different types of rocks penetrated, the water saturation as well as the formation porosity as the drilling progresses. Considering that the environment on the rig floor can be extremely noisy, there is no two-way communication and the communication from the tool to the surface is often very slow.

The LWD tool is generally integrated with the bottom hole assembly that is situated right above the drill bit. Hence, whenever the bit drills a hole through any formation, the characteristics of the formation are almost instantaneously gathered.

Very often, logging while drilling (LWD) is confused or interchanged with measurement while drilling (MWD). However, both these terms are not really the same. The data collected from an LWD tool aids in characterizing the drilled formation. The MWD tool assists in navigating and controlling the ‘well’ path.

How does Logging While Drilling work?
The information that is collated downhole through logging while drilling can be relayed to the surface through mud pulse telemetry. The drilling mud is circulated from the surface down to the bit. It then goes up to the surface again and as a result pressure pulses are generated in the drilling mud downhole. The transmission of the pressure pulses to the surface happens through the drilling mud.

All the LWD data is encoded in these pressure pulses. As the drilling keeps progressing, it gets sent to the surface where it gets detected by pressure transducers. These transducers are located at the surface and real-time data about formation properties penetrated by the bit are thus captured.
The LWD tool is capable of storing data in memory for downloading at a later time. This can be done when the drill string is pulled out of the hole. Data about other drilling parameters such as torque and downhole temperature and pressure are also collected.

Advantages of Logging-while-drilling
Logging while drilling has multiple benefits and advantages compared to conventional ‘well’ logging solutions. The key benefit is that data can be gathered in real-time and before sources of data contamination become severe.
Multiple rock types such as carbonates, shale, and sandstone can be differentiated in real-time as drilling progresses by running a gamma ray log with the bottom hole assembly. When compared to wireline, LWD can be used in deviated or high-angle wells.

Overall, LWD enables teams to measure temperature, vibration shocks, and borehole pressure among others. These measurements then need to be swiftly analyzed. While a lot of software relies on 2D graphs to analyze LWD data. If the data is analyzed in 3D software, the ‘well’ path reaching its intended target can be ensured.

Hunt and Hunt is a premier manufacturer of Logging While Drilling tools and other important resources for the oil and gas industry. With a production facility that features over 100,000 square feet of manufacturing space, Hunt and Hunt utilizes a variety of custom-built, multi-axis machining centers to offer quality and precision.
For more details click here https://huntandhunt.com/lwd-logging-drilling-tools/