Advanced Petrophysical, Geological, Geophysical and Geomechanical Reservoir Characterization – Key to the Successful Implementation of a Geo-Engineered Completion Optimization Program in the Eagle Ford Shale

Abstract

A geologically engineered shale completion optimization program was implemented for a liquid rich area of the Eagle Ford play. This approach included detailed geological characterization, state-of-the-art unconventional 3D hydraulic fracture and reservoir flow modeling, as well as the latest available surveillance technology. This paper focuses on the geological characterization of reservoirs which includes the generation of core-calibrated petrophysical and geomechanical rock properties as well as the natural fracture distribution.In the last decade, multistage completion in horizontal wells has successfully unlocked tremendous hydrocarbon resources in the onshore US. However, there are a large amount of wells which underperform due to oversimplified petrophysical and geomechanical property description, where reservoir heterogeneity is not properly represented. Low initial production rate is partially related to the poor uniformity among perforation clusters. Conventional subsurface reservoir description commonly involves the interpolation of core and log data acquired in pilot wells. The assumption of layer cake earth models from pilot wells can result in inaccurate reservoir property models for hydraulic fracture stimulation.Optimizing completion design requires acquiring and interpreting petrophysical and geomechanical properties along the horizontal well. Petrophysical properties include total organic content, porosity, permeability, gas-filled porosity and clay volume. Geomechanical parameters include minimum horizontal stress, Young's Modulus and Poisson's ratio. Alternative isotropic and anisotropic stress profiles of reservoirs and encasing rocks are used to simulate hydraulic fracture initiation and propagation as well as expected well performance. In addition to the later static properties, the density and orientation of natural fractures from borehole image and acoustic logs enhance the optimization workflow. This paper provides specific examples on how natural fractures and geological properties affect completion efficiency and production.Cutting-edge surveillance monitoring tools (i.e. fiber optics) confirmed an improvement of perforation cluster uniformity. The in-depth petrophysical and geomechanical reservoir description coupled with the optimized completion design yielded a 30% increase of the initial production rate in a well compared to an offset well having a simple geometrical completion design.

Advanced methods for the evaluation of a hybrid-type unconventional play: The Bakken petroleum system

“…The use of elastic moduli for estimating in situ stress combined with rock strength properties for hydraulic fracture modeling is well documented for vertical wells (Cherian et al, 2006;Higgins et al 2008;Panjaitan et al, 2011;Gonzalez et al, 2012) and more recently for hori-zontal well completion optimization (Cipolla et al, 2011;Wutherich and Walker, 2012;Slocombe et al, 2013;Han et al, 2014;Pirie et al, 2015;Sun et al, 2015). A thorough discussion of VTI anisotropy, rock mechanical models, and in situ stress can be found in Fjaer et al (2008).…”