Shunde Yin

Fully Coupled Numerical Modelling of Ground Surface Uplift in Steam Injection

In enhanced oil recovery, steam injection involves high stresses, pressures, temperatures and volume changes. Traditional reservoir simulation fails to predict associated transient ground surface movements because it does not consider coupled geomechanical effects. We present a fully-coupled, thermal half- space model using a hybrid DDFEM method, in which a simultaneous finite element method (FEM) solution is adopted for the reservoir and the surrounding thermally affected zone, and a displacement discontinuity (DD) method used for the elastic, non-thermal zone. This approach provides transient ground surface movements in a natural manner.

Impact of elliptical boreholes on in situ stress estimation from leak-off test data

We developed an inversion technique to determine in situ stresses for elliptical boreholes of arbitrary trajectory. In this approach, borehole geometry, drilling-induced fracture information, and other available leak-off test data were used to construct a mathematical model, which was in turn applied to finding the inverse of an overdetermined system of equations. The method has been demonstrated by a case study in the Appalachian Basin, USA. The calculated horizontal stresses are in reasonable agreement with the reported regional stress study of the area, although there are no field measurement data of the studied well for direct calibration. The results also indicate that 2% of axis difference in the elliptical borehole geometry can cause a 5% difference in minimum horizontal stress calculation and a 10% difference in maximum horizontal stress calculation.

Petroleum Geomechanics: A Computational Perspective

Petroleum geomechanics is concerned with rock and fracture behavior in reservoir, drilling, completion, and production engineering. Typical problems in petroleum geomechanics include subsidence, borehole stability, and hydraulic fracturing. All are coupled problems that involve heat transfer, fluid flow, rock/fracture deformation, and/or solute transport. Numerical solutions through modeling are desired for such complicated systems. In this chapter, we present the mathematical descriptions of these typical problems in petroleum geomechanics, point out the challenges in solving these problems, and address those challenges by a variety of classical and emerging numerical techniques.