Abstract

In sedimentary rocks, both conventional and unconventional reservoirs are a great energy asset. Seismic velocity profiles are routinely used to explore the attributes of both reservoirs from the vertical direction, though they are fundamentally different types of hydrocarbon resources. Subsurface geologic media are typically complex and heterogeneous due to the presence of various weak planes and different mineral compositions. Thus, it is important to explore the attributes of both reservoirs throughout the horizontal direction as well.

This study measures unconfined compressive strength (UCS) and elastic properties along horizontal orientations using three different rock types. The conventional core is of the Berea Sandstone, and the unconventional cores are of an Middle East carbonate and the Eagle Ford Shale (Fig. 1). Both UCS and elastic properties are measured by non-destructive laboratory equipment using the rebound hardness test device (Fig. 2) and the radial acoustic scanning device (Fig. 3), respectively. The hardness test device measures unitless rebound hardness numbers over the lateral surface of full-diameter cores and calibrates them using the empirical calibration equation to convert to the corresponding UCS values (Lee et al., 2014). The radial acoustic scanning measures primary and secondary wave velocities (as shown in Figure 4) and the velocities are converted to dynamic elastic properties (such as Young’s modulus and Poisson’s ratio). These laboratory experiment will reconstruct the azimuthal variations of rock mechanical properties (including UCS and elastic properties) along the horizontal direction using the three different rock types.

This study aims to determine, visualize, and compare the horizontal heterogeneity of rock mechanical properties measured from conventional as well as unconventional rocks in the laboratory. As a result, this laboratory observations will provide valuable insights toward developing a guideline for exploring rock fabric along the horizontal azimuth in reservoir formations. Also, it can provide a guidance for horizontal drilling optimization, wellbore stability, and completion design.