Integrated Methodology for Laboratory Evaluation of Shale Plays Cuttings

Abstract

This current paper is intended to show the implemented methodology for integrated mineralogical, geochemical, petrophysical characterization of Shale Plays from the analysis of well cuttings at the Colombian Petroleum Institute (ICP). The implemented methodology starts with taking drilling cuttings (Wet Trench samples) during the drilling of exploratory wells in areas of interest for production of Shale Oil & Gas in diferents Colombian basins. Then fragments are selected (picking) with stereoscopic magnifiers. Observed proportions and lithology in the Formation Evaluation Log (FEL) for a given range should be consistent. Subsequently, the textural and compositional macroscopic description of each sample using Hydrochloric Acid (HCL) to identify carbonates is performed. This description takes into account the degree of effervescence and solid waste analysis. Finally, the percentages of every lithotype present per interval are defined, and this way samples are selected for evaluation. The evaluation of texture and composition of samples was performed by conventional Petrography of relative abundance of elements by means of Scanning Electron Microscopy (SEM). The mineralogical evaluation of samples is performed by X-ray Diffraction (XRD). Furthermore, geochemical analysis of TOC and pyrolysis are performed in some fragments of the selected samples. Other tests include: Mercury Injection Capillary Pressure analysis (MICP), helium porosity, nanoindentation technique. These analyzes are made to determine mechanical properties of the rock. The integrated analysis of these techniques provides information to the mineralogical, geochemical and petrophysical characterization of rocks from a shale plays. This allows defining areas of interest for hydraulic fracturing and production in a UnConventional Reservoirs. The methodology was validated with results obtained from core samples from well Iwana-1 drilled by Ecopetrol in unconventional reservoirs in Middle Magdalena Valley Basin (MMVB). This fact provided competitive advantage to Ecopetrol in exploration and exploitation of Shale Plays. This mineralogical, geochemical and petrophysical characterization laboratory methodology for Shale Plays from well cuttings was used during 2014 at the ICP to characterize 880 ft at El Tablazo Formation in well Casabe K1, 850 ft at La Luna formation in well Golosa 1 and 5,900 ft at Gala 1K at the same formation. This methodology allowed shortening the laboratory analysis time from 120 to 60 days with respect to laboratory tests on a core of 800 ft