Getech holds the most comprehensive, industry-leading gravity database for the Permian Basin – leading to higher clarity of fault mapping and insight into induced seismicity.
These data constitute a vital component of any exploration campaign and are a cost-effective partner to seismic and well data. Gravity and magnetic data can quickly provide the basis for confident, and consistent, fault mapping over a large area – even where seismic and well data are sparse.
Getech’s gravity database in the Permian Basin comprises an unparalleled resolution – significantly higher than data available from the public domain. This is clearly illustrated in the images below, where Getech’s increased data coverage – shown in image A – results in dramatically more anomaly detail, as shown in image C, when compared to the sparce coverage and resolution of the corresponding public data, images B and D.
Getech’s comprehensive gravity data coverage (A) in comparison to public domain data coverage (B). The additional level of detail this enables is demonstrated in the first vertical gravity derivative from Getech’s proprietary compilation (C) and the public domain (D). Purple polygons define three major geological units in Permian Basin: Delaware Basin, Midland Basin and Central Basin Platform.
In the Permian Basin, induced earthquakes have been triggered by hydraulic fracturing along weaknesses caused by pre-existing faults. Getech have developed a unique, proven workflow, rooted in gravity and magnetic data, that can rapidly help mitigate the risk associated with induced seismicity.
This unique workflow utilises filters and derivatives of the gravity and magnetic data to compile a regionally consistent structural interpretation. The structural interpretation is carried out in two parts, firstly using our proprietary, unbiased, automated lineament analysis (ACLAS) which has the benefit of identifying of subtle lineaments that may be dismissed during a manual interpretation but does not consider geological information, and secondly by manual interpretation that also incorporates geological information, published literature, topography data and satellite imagery.
A further set of analyses are carried out on the structural interpretation, investigating their propensity to dilate under the present-day stress regime (Fault Dilatancy) and to assess the distribution of fault damage across the area of interest (Fault Damage) (Figure F). These analyses are performed within a rapid geoprocessing workflow developed by Getech.
The maps below show a cluster of induced earthquakes* located in an area of the Central Basin Platform. This group of earthquakes plots where a high number of closely spaced, large, highly dilatant faults cluster and intersect, attributes which together contribute to an elevated damage score. Regions of coincident high dilatancy and high damage should be approached with caution as they have a higher risk of induced seismicity.
Structural faults mapped from Getech’s data (E) and) Induced earthquake (yellow circles) and faults (coloured with high dilation in black and low in light grey) overlain on calculated damage scores (green high to red low damage) (F).
Written by Kaxia Gardner, Senior Geophysicist, Getech
* Data were downloaded from HiQuake – The Human-Induced Earthquake Database, which is most complete database of anthropogenic projects proposed, on scientific grounds, to have induced earthquake sequences.
Reference: Wilson, M.P.; Foulger, G.R.; Gluyas, J.G.; Davies, R.J.; Julian, B.R. (2017). “HiQuake: The human-induced earthquake database”. Seismological Research Letters. 88 (6): 1560–1565. Bibcode:2017SeiRL..88.1560W.
