Stretched by the energy market realities of the past few years, the energy industry is going through continuous and rigorous cost-cuttings and optimizations. This low-cost environment often resulting in key data are not obtained while the need for high-quality reservoir characterization services still remains. Specifically, for geomechanical rock characterization which traditionally relies on the collection of core samples and subsequent analysis, and the acquisition of downhole logging suites. The geomechanical work has suffered under this cost pressure. As a result, many geomechanical models are built on assumptions that may introduce project uncertainties, rather than remove them.  

After several years of development and pilot studies, SGS released to the market in 2020 its novel workflow for Automated Rock Properties by Indentation (ARPIN), an integrated approach using drill cuttings for geomechanical rock characterization.

Given that drill cuttings are usually available for any wells drilled, the ARPIN workflow facilitates the derivation of micro-rock mechanical properties for any section of the intersected geological horizons. The method combines detailed mineralogical analysis using QEMSCAN technology and nano-indentation measurements (Hofmann et al., 2015; de Block et al., 2014). Information from both methods is used to construct a digital rock model, where all relevant geological characteristics of the rock formations of interest are integrated, including e.g. layering, mineral distribution, and porosity. Finite element modeling is then used to calculate the bulk mechanical properties for each selected rock types. The results from the ARPIN workflow provide input for 1D geomechanical modeling as calibration of the dynamic (sonic logs) to static correlations.

In hydraulic fracturing activity, for instance, the application of drill cuttings analysis with ARPIN offers clear benefits when compared to the conventional core samples analysis. Continuous data availability of drill cuttings contributes to a more robust and reliable fracturing design. In that situation, core samples are typically recovered only from the zone of interest (expected producing zone) and have limited interval depth coverage (i.e., a point sample). Therefore, log data are required to provide further information about fracture containment. In contrast, analysis on drill cuttings can be conducted over continuous interval covering the entire zone of interest, allowing a more refined understanding of the mineralogical and geomechanical variability over any depth interval. As a result, the variations of static mechanical properties over the interval of interest can be built into the 1D geomechanical model. This, in turn, can be used to develop a more representative simulation of fracture geometry and prediction of fracture impact to reservoir production. In addition, with continuous drill cuttings availability, geomechanical information for the top and bottom barriers can be obtained, to gain additional insights that contributes to the success of the fracking campaign.

In this paper, we present the application of ARPIN to optimize the simulation of fracture geometry and prediction of fracture impact to reservoir production. Based on the case studies, we demonstrate that drill cuttings evaluation for geomechanical properties can lead to more reliable geomechanical modeling as well as tangible cost savings, thus successfully contributing to de-risking stimulation campaigns and optimizing overall project costs.