Line-based ergodic sampling and application in airborne magnetic data acquisition

Airborne geophysical data are widely used in energy and mineral exploration industries as well as in the regional and crustal studies. Despite widespread use of such data, the high cost remains a hurdle to acquiring the airborne data in large areas. Line-based ergodic sampling provides a novel approach to the design of specific patterns using the same amount of line-kilometers to cover a larger area. The ergodic sampling was developed originally with focus on point-wise observations and its applications to structured irregular observation points have been examined, but the specifics and results of these investigations are not directly applicable to data acquisitions using receivers that must be arranged along the virtual lines (e.g., flight lines of the traditional aircraft or newly available drones) or physical lines (e.g., cables with sensor or fibers in distributed acoustic sensing (DAS)). We refer to these receivers constrained to a set of lines as line-shaped or line-based sensors. We examine the application of ergodic sampling to the special case of line-based sensors and the associated ergodic sampling design. Similar to the cases of point observations, we show that using ergodic sampling can improve the line-shaped acquisitions by either reducing the cost and covering larger areas, or by increasing the acquired information, with the same line-km based on the given budget. Our simulations show that line-based ergodic sampling is superior to regular sparse acquisition designs that assume an equal line spacing by default. Our examples on airborne magnetic data demonstrate that we can save up to 20% of the cost using the design pattern from line-based ergodic sampling. Equally importantly, the use of ergodic sampling in airborne surveys with the same line-km has the potential to acquire high-resolution in the same area. • We have developed a line-based ergodic sampling method and workflow for more efficient geophysical data acquisition by using a smaller number of lines deployed in an optimized irregular pattern. • The line-based ergodic sampling method can either save the cost over dense regular line surveys or increase the information acquired by using the same total length of lines. • Field data example on the airborne magnetic data shows that 80% of flight lines can be saved.