A Consistent Method to Build and Use a 3D Mechanical Earth Model

摘要

The document presents a consistent method to build 3D Mechanical Earth Models(3D MEM).It is basedon a rock physics study to derive field specific correlations between mechanical properties and interpretedpetrophysical quantities.The 3D MEMs built using this methodology yield robustness and consistencywhen matching to the measured minimum stress.They also display good predictive capabilities makingthem valuable for operational design.This method consists of conducting a preliminary rock physics study in order to obtain correlationsbetween the mechanical properties(elastic moduli and strength),of the various formations that areconsidered,and basic interpreted quantities which are readily available in most 3D geological models(porosity or mineralogy).The correlations are used to build a 3D MEM which is consistent with both the3D geological model and the 1D geomechanical interpretation.It is also possible to extend the correlationsby linking raw log data to rock mechanical properties.The model was tested against field case study to verify its predictiveness.Minimum stresses calculatedby the 3D MEM matched well to the measured values obtained from mini-frac tests performed at variouslocations.Ultimately it permits to better forecast the material properties(in 3D)as well as the effective stresstensor(in 4D).The 3D MEMs were used to evaluate the risks for infill drilling,and for completion purposes.Performing this type of preliminary rock physics study has a number of benefits.Firstly,to help identifywhich logging suite should be run to characterize the geomechanical properties of a given formation,andsecondly it can be used to derive correlations between raw log data and geomechanical properties.Thesecorrelations can be applied during operations for real time decision making purposes when there is not yeta petrophysical interpretation available.The novelty of the method introduced lies in the systematic and coherent integration of data to build aconsistent geomechanical model(3D or 1D),that exhibits a robust predictive capability and shows the valueof 3D MEM for the design of drilling and completion operations.