Geomechanical Analysis to Develop an Extra Heavy Oil Offshore Field

Abstract

Abstract Recent advances in petroleum geomechanics numerical simulations have encouraged industry to invest in finite element simulations to optimize drilling operations. One important part of the drilling process is to understand the rock mechanics behavior, such as deformation and strength through a stress-strain behavior. This work presents the case of study of an exploratory field located at the south of the Gulf of Mexico. This field has two offset wells already characterized by a post mortem 1D MEM (Mechanical Earth Model) study, faults and horizons already interpreted in depth. The principal objective of this study was to develop a consistent in-situ stress state of this field through an in-house finite element program with the help of geoscience analysis & data generation software. The final product of this work will help deliver a consistent stress analysis for the drilling of a planned well in the same field. The rock formation was modeled through a non-linear model. A Mohr-Coulomb with unconfined compressive strength input was used to simulate the formation. The finite element mesh representing the field was fed with elastic and geomechanical properties from the geoscience software, allowing the discretization of the different formations and faults also. Initially this mesh had a size of 74*74*42 and then it was embedded (104*104*62) to let far field stresses act on it. After many simulations the stresses obtained from the simulation were validated against the two offset wells and they showed good agreement. One of the principal variables of this field is the fault structures and how they affect drilling. The 3D geomechanical model concept is a complete process that allows a comprehensive analysis first in loading the grid with mechanical properties, editing the mesh, appending faults, assigning mechanical properties and finally specifying initial stress conditions like stress gradients, directions and magnitudes of horizontal principal stresses and seawater surcharge.