Abstract

Subsidence Monitoring using ArcGIST Spatial AnalystT, South Belridge Field, California
Track: Petroleum
Authors: Matt Schreiner

Ground subsidence is a leading cause of well failure in the highly porous Miocene Diatomite. Traditionally, total subsidence is used to predict well failure by focusing on compressional strain in the area of greatest subsidence. However, shear, the differential between one area of subsidence and the next, is best correlated to well failure.



Contracted surveys conducted monthly document changes in elevation throughout the field to determine areas of greatest subsidence. The survey data show areas of high subsidence highlighting potential for vertical compression failures when displayed as a grid in ArcGIST, but do not reveal shear.



By using the 'slope' and 'aspect' tools in ArcGIST Spatial AnalystT, a map can be generated representing the direction of the rate of change of subsidence from month to month. This 'shear vector' map has provided an enhanced visual reconnaissance to better identify and more effectively manage reservoir voidage replacement needs.