Effective Multi-Scale Rock Characterization Using Digital Rock Physics Applied to La Luna Formation, Middle Magdalena Valley Basin, Colombia

Marfisi, Nelbett K.¹; Galvis-Portilla, Henry A.; Cantisano, Maria; Restrepo, Dora; Zamora, Wilson H.; Diaz, Elizabeth; and Walls, Joel
¹[email protected]

La Luna Formation in northern South America is one of the most prolific hydrocarbon source rocks of the world. Recently, La Luna Formation has also gained a significant exploration potential as an unconventional oil/gas target in Colombia. Recent developments in Digital Rock Physics (DRP) technologies allowed to conduct a multi-scale rock characterization study on approximately 2900 ft. of core recovered from La Luna Formation in the Central Part of the Middle Magdalena Valley Basin (MMVB) in Colombia.

The DRP technique was specially designed for the characterization of highly heterogeneous rock intervals following a three stage multi-scale approach which provides qualitative and quantitative information. In the Stage 1, borehole cores are analyzed using calibrated X-ray Computed Tomography (CT-Scan) imaging that provides structural and stratigraphic insights. Concurrently, bulk density (RhoB) and effective atomic number (Zeff) logs are measured on the core for quantitative measures of mineralogical composition and porosity. In the Stage 2, plug-size samples are taken at multiple depths on the intervals of interests identified in Stage 1. For each plug sample a Micro-CT Scanning and 2D SEM analyses are performed in order to quantify the organic matter content, porosity and high-density minerals. In the Stage 3, representative samples previously selected from SEM images analysis in Stage 2, are analyzed using 3D Focused Ion Beam Scanning Electron Microscopy (FIB-SEM) techniques to generate 3-D rock volumes, providing information about connected and isolated porosity, kerogen volume fraction and distribution, and absolute permeability in x, y and z directions. This methodology provides heterogeneity characterization of this unconventional porous media at different scales.

This multi-scale work flow for DRP characterization allowed identifying organic-matter-rich siliceous and calcareous intervals which represent outstanding targets for unconventional reservoir exploration and provides key elements for prospective intervals recognition in La Luna Formation. Moreover, results from this study provide new insights on petrophysical properties distribution for future reservoir stimulation. The integrated DRP study -from core to pore- provided a fast and efficient understanding, identification and characterization of the main intervals in the well.

AAPG Search and Discovery Article #90166©2013 AAPG International Conference & Exhibition, Cartagena, Colombia, 8-11 September 2013