Landstreamer Project

Objective

The objective of this project is “How can we record shallow seismic data faster than the conventional way, but with the same accuracy and signal-to-noise ratio”. To achieve this objective we are using landstreamer seismic.

The landstreamer is designed in the seismology lab then the prototype was made at the KAUST’s workshop (Building 4). The Landstreamer assembly and testing was made in the lab seismology (Figure 1).

Before we go to the field, we need to test the connections of each receiver to the receiver cable, test the whole system with seismograph connected (Figure 2).

After field work, Land streamer and other equipments need to be cleaned and maintained before storing them for future field survey.

Since this is a new system that was designed and manufactured at KAUST, we need to test it in the field, find problems, bring it back to the lab to modify the design to overcome these problems, and repeat the whole process again till we reach a satisfactory point.

We also expect that the system may need minor modifications according to the site where we will use it, is it flat surface covered with sand, is there any small/large topographic changes (Figure 3), bushes, roads, etc.

Figure 1: The assembly and test of the newly designed landstreamer

Figure 2: The landstreamer in the field, this site is located 5 km north of KAUST and inside the Economic city. We are tracking the Qademah fault using the landstreamer.

Figure 3: The landstreamer system is used at an area with some topographic changes and large rocks on the surface, Wadi Qadied, 40 km north of KAUST.

Field Test

Figure 4 shows a conventional shot gather (Figure 4a) and its corresponding land streamer shot gather (Figure 4b). Comparing both shot gathers show a very good agreement between them. Both first arrivals and later arrivals are very similar. The land streamer shot gather (Figure 4b) shows a lower signal-to-noise ratio (SNR), especially before the first break; however, the first break and later arrivals are easily recognized.

Figure 4: Shot gather # 74 for both (a) conventional and (b) land streamer data set.

The amplitude spectra of the conventional and land streamer data sets are shown in Figure 5. Here, we show the normalized summation of amplitude spectra for all traces in shot gather # 74. Both data sets show almost the same frequency content with peaks at the same frequency values (22 Hz), however, the conventional seismic data set contains more energy especially at frequencies higher than 30 Hz. This probably due to the better coupling of conventional receivers with the ground, this will record high frequency signals with less noise than the streamer’s receivers.

Figure 5: The frequency spectrum of both conventional (red) and land streamer (blue) data sets.