The impact of faults on fluid flow in the Heidrun Field

Authors:
Publisher website
Google Scholar
Abstract
A quantitative analysis of fault seal properties has been used in reservoir simulation modelling in the Heidrun Field. The inclusion of microstructural and petrophysical data from core analysis has resulted in a better prediction of reservoir communication and drainage patterns during production. Three main fault rock types were observed in the Heidrun cores, namely; cataclasites developed from clean sandstones, phyllosilicate framework fault rocks , created from impure sandstones and clay smears . The clay content of the host sediment is the controlling factor in determining which fault rock type dominates in the fault zones. Fault plane geometries were assessed from seismic-based juxtaposition analysis for input into the reservoir simulation model. The fault planes were divided into areas following the reservoir zonation, and transmissibility multipliers were assigned to each subarea of the fault planes in the model. The transmissibility multipliers are a function of fault rock permeability and fault rock width, as well as the matrix (host rock) permeability and the dimensions of the grid blocks used in the simulation model. Introducing a quantitative description of the faults has had a significant effect on the results of the reservoir simulation runs and has played an important role in the successful modelling and prediction of the observed gas breakthrough and pressure evolution. After actively using the transmissibilities during history matching of the simulation model, a remarkably good match to the observed well rates and pressures (flowing and shut-in) for the Jurassic Fangst and Upper Tilje reservoir units was achieved.
Keywords

This publication has 12 references indexed in Scilit: