Abstract: One or more techniques for determining time-varying stress and strain fields within a subsurface region include integrating a seismic model (110) of a reservoir within the subsurface region with a geomechanical model (140) of the subsurface region. An estimate of the time-varying stress and strain fields within the subsurface region during production of the reservoir are determined, wherein the estimate is based on the integration of the seismic model with the geomechanical model. The integration of the seismic model with the geomechanical model can be used to predict the feasibility of passive seismic monitoring for a reservoir within a subsurface region (170).

Abstract: A method for predicting time-lapse seismic timeshifts in a three-dimensional geomechanical system including defining physical boundaries for the geomechanical system. In addition, one or more reservoir characteristics such as pore pressure and/or temperature history are acquired from multiple wells within the physical boundaries. The method also includes determining whether a formation in the geomechanical system is in an elastic regime or a plastic regime. The method also includes obtaining first and second seismic data sets for the geomechanical system, taken at first and second times. The method also includes running a geomechanical simulation to simulate the effects of changes in pore pressure or other reservoir characteristic on time-lapse seismic timeshifts in the formation.

Abstract: A method for modeling deformation in subsurface strata, including defining physical boundaries for a geomechanical system. The method also includes acquiring one or more mechanical properties of the subsurface strata within the physical boundaries, and acquiring one or more thermal properties of the subsurface strata within the physical boundaries. The method also includes creating a computer-implemented finite element analysis program representing the geomechanical system and defining a plurality of nodes representing points in space, with each node being populated with at least one of each of the mechanical properties and the thermal properties. The program solves for in situ stress at selected nodes within the mesh.

Abstract: Methods for creating and using space-time surrogate models of subsurface regions, such as subsurface regions containing at least one hydrocarbon formation. The created surrogate models are explicit models that may be created from implicit models, such as computationally intensive full-physics models. The space-time surrogate models are parametric with respect to preselected variables, such as space, state, and/or design variables, while also indicating responsiveness of the preselected variables with respect to time. In some embodiments, the space-time surrogate model may be parametric with respect to preselected variables as well as to time. Methods for updating and evolving models of subsurface regions are also disclosed.

Abstract: Methods for generating a surrogate model for subsurface analysis may include identifying input parameters for the subsurface analysis, and selecting a range of values for the identified parameters. The methods also include selecting a design of experiments method for filling sampling points within the ranges of values for the identified input parameters. The design of experiments method may be a classical method or a space-filling technique. The methods also include filling sampling points within the ranges of values for the identified input parameters. The sampling points are filled based on the design of experiments method selected. The methods further include acquiring output values for each of the selected sampling points, and constructing a surrogate model based upon the output values for at least some of the selected sampling points. The surrogate model is a mathematical equation that represents a simplified model for predicting solutions to complex reservoir engineering problems.

Abstract: Methods of predicting earth stresses in response to pore pressure changes in a hydrocarbon-bearing reservoir within a geomechanical system, include establishing physical boundaries for the geomechanical system and acquiring reservoir characteristics. Geomechanical simulations simulate the effects of changes in reservoir characteristics on stress in rock formations within the physical boundaries to determine the rock formation strength at selected nodes in the reservoir. The strength of the rock formations at the nodes is represented by an effective strain (?eff), which includes a compaction strain (?c) and out-of-plane shear strains (?1-3, Y2-3) at a nodal point. The methods further include determining an effective strain criteria (?effcr) from a history of well failures in the physical boundaries. The effective strain (?effcr) at a selected nodal point is compared with the effective strain criteria (?effcr) to determine if the effective strain (?eff) exceeds the effective strain criteria (?effcr).

Abstract: A method of predicting earth stresses in response to changes in a hydrocarbon-bearing reservoir within a geomechanical system includes establishing physical boundaries for the geomechanical system, acquiring logging data from wells drilled, and acquiring seismic data for one or more rock layers. The well and seismic data are automatically converted into a three-dimensional digital representation of one or more rock layers within the geomechanical system, thereby creating data points defining a three-dimensional geological structure. The method also includes (a) applying the data points from the geological structure to derive a finite element-based geomechanical model, and (b) initializing a geostatic condition in the geomechanical model, and then running a geomechanics simulation in order to determine changes in earth stresses associated with changes in pore pressure or other reservoir characteristics within the one or more rock layers.

Abstract: One or more techniques for determining time-varying stress and strain fields within a subsurface region include integrating a seismic model (110) of a reservoir within the subsurface region with a geomechanical model (140) of the subsurface region. An estimate of the time-varying stress and strain fields within the subsurface region during production of the reservoir are determined, wherein the estimate is based on the integration of the seismic model with the geomechanical model. The integration of the seismic model with the geomechanical model can be used to predict the feasibility of passive seismic monitoring for a reservoir within a subsurface region (170).

Abstract: A method for modeling a reservoir response in a subsurface system is provided. The subsurface system has at least one subsurface feature. Preferably, the subsurface system comprises a hydrocarbon reservoir. The method includes defining physical boundaries for the subsurface system, and locating the at least one subsurface feature within the physical boundaries. The method also includes creating a finite element mesh within the physical boundaries. The finite element mesh may have elements that cross the at least one subsurface feature such that the subsurface feature intersects elements in the mesh. A computer-based numerical simulation is then performed wherein the effects of the subsurface feature are recognized in the response. The reservoir response may be, for example, pore pressure or displacement at a given location within the physical boundaries.

Abstract: A method has been invented for predicting the build-up of heat, material aging, and subsequent belt separation failure in rolling steel-belted pneumatic tires (20). The procedure employs finite element analysis and a new fatigue crack propagation model that takes output generated by the finite element model to predict distance and time to belt separation in the tire. The finite element model uses input information on tire load, speed and inflation pressure (12) to calculate the temperature and energy release rate at the corresponding tips of the fatigue crack to generate four-dimensional response surfaces of crack-tip energy release rate as a function of crack length, crack-tip circumferential angular position, and crack-tip temperature. The fatigue crack propagation model samples the response surface and is numerically integrated to predict distance and/or time to belt separation failure (30).

Abstract: A method has been invented for predicting the build-up of heat, material aging, and subsequent belt separation failure in rolling steel-belted pneumatic tires (20). The procedure employs finite element analysis and a new fatigue crack propagation model that takes output generated by the finite element model to predict distance and time to belt separation in the tire. The finite element model uses input information on tire load, speed and inflation pressure (12) to calculate the temperature and energy release rate at the corresponding tips of the fatigue crack to generate four-dimensional response surfaces of crack-tip energy release rate as a function of crack length, crack-tip circumferential angular position, and crack-tip temperature. The fatigue crack propagation model samples the response surface and is numerically integrated to predict distance and/or time to belt separation failure (30).