Estimating in-Situ Stresses and Rock Mass Properties from Geological and Geophysical Data: Applications in the Hydraulic Fracturing of Tight Gas Reservoirs

摘要

Case studies are presented in which the orientation and magnitude of in-situ stresses are estimated. The estimates are based on geological mapping, geophysical logging, and materials testing. The case studies show that there has been some success in predicting stress orientation based on an analysis of geological and geophysical data alone. The acquisition of such data should be pursued because, without other input, it is still the only way to infer the hydrofracture orientations outside of those sites where results are known from actual fracturing operations. The case studies also show the uncertainties in attempting to predict horizontal stress magnitudes. A possible approach to reducing the uncertainty of predicting the direction and magnitude of in-situ stresses is to correlate geological and geophysical data with mechanical properties derived from core and in-situ tests. Such correlations would extend the results of other tests and enable more accurate extrapolations to other levels in a given wellbore or to locations at a distance from the wellbore. 68 references, 14 figures, 5 tables. (ERA citation 09:000198)