A Novel Approach to Model DFNs Validating the Geological Evolution with Present Day Fracture Distributions

Sarmiento, Sergio (Repsol) | Macaulay, Euan (Midland Valley) | Sifontes, Ventura (Repsol) | Arregui, Juan (Repsol) | Lakshmikantha, M. R. (Repsol)

OnePetro 

Abstract:

A new workflow for fracture prediction and modelling based on geological time-step DFN has been used to better constrain the fracture distribution and timing of generation in the Motatan Domo Sur field of Venezuela. Using the Fault Response Modelling module in Move™, simulations of fracture generation under two tectonic transpressive events with SHmax of 280° and 310° were modeled to find the best-fit fracture forming event as compared with the observed data. These events are of Paleocene-Eocene and Miocene age, respectively. This workflow includes a DFN built from borehole images of five wells whose fracture properties are spatially modeled taken into account structural and petrophysical indicators of sub-surface fracture systems. A comparison between measured and modeled fractures is discussed to evaluate the influence of each tectonic event.

Introduction

Modeling the location of discontinuities (faults and fractures) in the subsurface associated with a given tectonic event requires a geomechanical model, which incorporates stress boundary conditions and mechanical properties. In this paper, we outline a new workflow which allows fracture forming events to be simulated and used to predict fracture distributions across reservoirs; the results of these simulations can supplement petrophysical, geomechanical and subseismic indicators to produce more representative fracture models. This workflow is applied to the south dome of the Motatan reservoir, which is located in the tectonically complex Maracaibo basin of Venezuela.

This workflow consists of two phases: 1) the building of present day discrete fracture network (DFN) through the integration of petrophysical, geomechanical, structural and subseismic indicators of fracture systems (e.g. curvature and bore hole image data); and 2) the simulation of slip on faults, calculating the resulting strain field and comparing predicted fracture orientations for different tectonic events with the observed fractures. The combination of these two phases provides a better understanding of natural fracture systems and provides information about the development of reservoir fracture systems through time.