Geomechanik_unkonventionell_engl

Geomechanics for unconventional reservoirs

PhD thesis C.I. Guerra

Stress and fracture prediction in tight sand gas reservoirs

Fig.1 1D mechanical earth model. Rock mechanical testing results and field measurements were used to constrain elastic mechanical properties, pressure and minimum horizontal stress (Shmin). 1D profiles serve as input data to populate the 3D mechanical models.
Fig.1 1D mechanical earth model. Rock mechanical testing results and field measurements were used to constrain elastic mechanical properties, pressure and minimum horizontal stress (Shmin). 1D profiles serve as input data to populate the 3D mechanical models.

Proper characterisation of the mechanical and stress state of a hydrocarbon or geothermal reservoirs is crucial for optimal exploration and exploitation. The increasing complexity of discoveries push the boundaries of conventional methodologies which often rely on local laboratory measurements or well-derived properties that may not represent the actual spatial distribution of relevant characteristics of the area. The early and accurate knowledge of pore pressure, mechanical properties and in-situ stress represent critical information to promote reservoir exploration, well placement and enhanced recovery techniques as well as avoidance of risky locations. Numerical modelling approaches serve as the solving tool, as they can honor the heterogeneous and geometrical complexity of reservoir and associated structures.

Fig.2 Three-dimensional geomechanical grid comprising the actual Block A model (Reservoir area) embedded in side-, over- and underburden volumes to avoid edge effects. (A) Top view and (B) Side view.
Fig.2 Three-dimensional geomechanical grid comprising the actual Block A model (Reservoir area) embedded in side-, over- and underburden volumes to avoid edge effects. (A) Top view and (B) Side view.

This study evaluates the potential and pertinence of geomechanical modelling techniques for stress and fracture prediction. The methodologies performed in this research are applied to a tight sand gas reservoir located in the Lower Magdalena Valley Basin in northern Colombia. The target reservoir is an Oligocene to Miocene sequence known as Porquero formation which is composed of low-permeability sandstones and shale layers. The area has been explored for more than 30 years but, due to its difficulty to be adequately characterised, has only become of economic interest in the last decade, thanks to the implementation of advanced petrophysical and seismic methodologies. Exploitation of the Porquero formation will may require non-vertical drilling paths and hydraulic fracturing for economic production. Therefore an accurate understanding of reservoir mechanics and stresses is of critical importance.

The significant contributions of this research are fully customized 1D and 3D geomechanical reservoir models that are able to reproduce the reported mechanical behavior of the area but, moreover, are able to provide critical insights in the inter-well and undrilled regions of the model domain. The models are populated with actual field and laboratory data and are set to be the fundamental scenarios in any predictive simulation. The methods presented in this work are replicable and deployable in any other geographical and tectonic setting.

Publications

Guerra, C., Fischer, K., Henk, A., 2019. Stress prediction using 1D and 3D geomechanical models of a tight gas reservoir—A case study from the Lower Magdalena Valley Basin, Colombia. Geomechanics for Energy and the Environment (2019), https://doi.org/10.1016/j.gete.2019.01.002

Conference Contributions

Guerra, C., Fischer, K., Henk, A., 2019. Present-Day Stress State Prediction of a Tight Gas Reservoir Using Geomechanical Models —A Case Study From the Lower Magdalena Valley Basin, Colombia. AAPG ACE. 19-22 May 2019. San Antonio, Texas.

Guerra, C., Hidalgo, J.C., Henk, A., 2019. Integration of Basin Modeling and Geomechanics for Stress and Fracture Prediction —A Case Study From the Lower Magdalena Valley Basin (Colombia). AAPG ACE. 19-22 May 2019. San Antonio, Texas.

Guerra, C., Henk, A., Hidalgo, J.C., Castillo, L., 2017. Integration of petroleum systems and geomechanical modeling workflows Case study: Lower Magdalena Basin (Colombia), DGMK Frühjahrstagung 05.-06. April 2017, Celle, Germany (Poster).

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