New LWD-NMR tool unveiled for slimhole applications

Saudi Aramco has announced the successful development and launch of its small-hole Logging-While-Drilling (LWD) Nuclear-Magnetic-Resonance (NMR) tool, a reported industry first. The tool, developed in collaboration with Baker Hughes, uses NMR technology to obtain real-time measurements in angled and horizontal wells of small diameters.

The Saudi Aramco EXPEC Advanced Research Center (EXPEC ARC) developed the tool over two years based on an industry need for a next-generation NMR technology for making better drilling decisions in real time. NMR is a technique that exploits the magnetic properties of nuclei of certain atoms—in this case hydrogen—that contain odd numbers of protons or neutrons. In the presence of a magnetic field, the hydrogen nuclei emit a representative magnetic resonance signature.

While NMR spectroscopy has been commonly applied in magnetic resonance imaging (MRI) for medical diagnosis, the oil and gas industry has adapted the technique to diagnose the quantity of hydrogen within a rock space. This hydrogen is associated with water and hydrocarbon, and thus the NMR technique reveals rock-pore characteristics as well as how much hydrocarbon and water are present.

LWD is considered the most effective way to evaluate a reservoir in real time using tools deployed in the drillstring. These tools acquire different logging measurements that are combined to provide a more integrated picture of reservoir conditions, hydrocarbon abundance, fluid properties, and so on. The information is then sent from the tool to the wellhead through pulses in the drilling mud, and then travels via satellite to a drilling control center.

NMR logging has been used in the oil field for numerous applications over the past two decades, including pore geometry measurements, improved design of hydraulic fracturing treatments, formation evaluation, asset management optimization, and real-time geosteering support. This new application marks the first time that NMR and LWD technologies have been combined for the successful evaluation of slimhole applications, according to Saudi Aramco.

The company has deployed two prototypes in its fields. The first LWD NMR tool, measuring 12 cm in diameter, was run in combination with other LWD tools in a 1524-m section of the Arab reservoir and accurately measured porosity and other reservoir properties. A second tool was reportedly deployed in a well of a different field, with similar success.

According to Muhammad Saggaf, Manager of EXPEC ARC, this tool will be critical to the development of tar-containing reservoirs. “It will provide us with real-time estimates of the presence of tar and therefore guide our geosteering capabilities in many of our fields. Now, we can be more successful in avoiding the troublesome tar zones and in complementing our rock and reservoir analysis.”