Predictive Fracture Modeling: Example Fields From Saudi Arabia

Abstract

AbstractThis brief study was initiated to evaluate predictive fracture modeling based on structural geology and geomechanics. The trials with two fields show encouraging results. In strike-slip enviroments, superposition of local stresses cause by structural deformation and the regional Paleo-stresses assisted to predict the strike and risk zones for fold-related fractures successfully.The main challenge is estimation of paleo-stress orientation and magnitudes. For this is necessary to have at least one field in a region with actual fracture measurements and models from borehole image logs and production data. The predicted fracture models for different paleo-stress orientation and direction are calibrated to the actual observed fracture models to estimate the prevailing Paleo-stress at the time of deformation.For structures which are composite product of multiple pulses of deformation, it is possible to predict fracturing at each phase by using the isochore maps and the latest phase by using the structural grids of the youngest deformed horizon. This requires a detailed tectonic evolution of the structure which must always be the first step in predictive fracture modeling. An understanding of the nature of structure, tectonic regimes that prevailed and timing and origin of tectonic pulses and folding in relation to the regional faulting are essential for predictive fracture modeling.Predicted risk zones are not only useful in developing new fields for planning but also in mature fields with a descriptive fracture model. Often, the descriptive fracture model displays only what has been intersected in well bores and the fracture model may not capture the essence of fracturing tendencies, and miss risk zones completely. Predicted modeling accompanied with an understanding of the tectonic evolution and structural geology may add invaluable insight and support to descriptive fracture modeling.