LAUSR

When designing an oilfield development program and deploying well patterns, it is often assumed that the maximum principal stress is along a single direction. A wrong determination of the principle stress may cause early water breakthrough and thereby abate production results. In-situ stress field has significant impacts on well pattern design and hydraulic fracturing. To obtain the distribution of a 3D in-situ stress field for a research area, the single-well in-situ stress curves were built by synthesizing laboratory experiments, fracturing results, and experienced formula and logging information. A 3D in-situ stress model was built by stochastic modeling. First, the relationship between vertical compressional wave velocity and longitudinal compressional wave velocity was established. Then, a calculated model of corrected rock mechanical parameters model was built with a triaxial rock mechanics testing system, and a modified tectonic stress coefficient was established according to fracturing data. In accordance with the calculated model and correction coefficient, the single-well in-situ stress variation curve is then determined. Base on the obtained single-well curve, a logging curve, a 3D in-situ stress model of the area was built by applying the stochastic modeling method. Further applications of the 3D in-situ stress field model were finally demonstrated through comparison of simulated results with field monitoring data in Ordos Basin. The results demonstrated high accuracy of the new model and therefore provided guidance to reservoir simulation and well pattern design for low-permeability reservoirs.