Integrating Multiple Datasets to Characterize Heterogeneity Across a Lateral Well-Bore

Abstract

Unpredictability of production is one of the biggest problems facing the development of unconventional reservoirs. This is largely because subtle differences in depositional and post-depositional environments contribute to lateral heterogeneity. These differences can be mapped using multiple techniques. In this case study, we combine pyrolysis and X-ray diffraction of cuttings with mud gas analysis using mass spectrometry. Geometric completions are typically used on horizontal wells in unconventional reservoirs. Unfortunately, 15–20 percent of hydraulic fracturing stages and 35–40 percent of perforation clusters may not contribute to production, suggesting that a more customized treatment is called for. Laboratories have been characterizing rock, geofluid and organic matter types for decades using XRD, XRF, pyrolysis and mass spectrometry. Only recently have innovations allowed us to perform these same tests at the wellsite. Integrating these wellsite datasets gives key insights into reservoir heterogeneity, which critically affects the economics of completion designs and production. Our example uses data from a horizontal well. Throughout the lateral, changes in Tmax values and associated kerogen types correlate generally with transitions between mineralogically defined lithotypes. Several zones of special interest occur. In one interval, both mass spec and pyrolysis data show indications of lighter hydrocarbons—condensate or lighter oil—than in the rest of the lateral. In short zones throughout the lateral, high relative helium abundance, sulfur content, and aromatics suggest areas of high permeability, possibly due to fractures that have introduced water- and sulfur-rich fluids. One possibly problematic section shows these indications of possible fracture zones, as well as high clay content (and therefore low brittleness). However, this section also has good hydrocarbon indications from mass spec and pyrolysis. The treatment of this and other sections is up to the operator. Still, these sort of combined datasets suggest that perhaps completions should not be standardized across the lateral. A more customized approach may improve well economics.

AAPG Datapages/Search and Discovery Article #90217 © 2015 International Conference & Exhibition, Melbourne, Australia, September 13-16, 2015