Measuring Elastic Properties to determine the influence of TOC on Synthetic Shale Samples

Shale elastic property relationships as a function of total organic carbon content using synthetic samples

“…In the literature, core measurements have stated that the presence of high TOC content on the organic shale reduces both velocity and density, while increasing velocity anisotropy. Organic shale also affects the effective Vp/Vs of the rock (Altowairqi et al, 2015;Altowairqi et al, 2013;Vernik and Milovac, 2011). Table 1 shows measured ultrasonic wave velocities with different TOC content.…”

“…Therefore, it is difficult to account for all the factors affecting the velocity and anisotropy of a real shale sample. In particular, factors including stress state, stress history, clay mineral content and TOC content are not widely reported (Altowairqi et al, 2015;Bohacs et al, 2005) have investigated the impacts of the stress, lithology and TOC content on wave velocities using real shale core samples from the Perth Basin (Altowairqi et al, 2015;. The results showed that the velocities increased with the stress levels and the velocities decreased as the TOC percentage increased.…”

“…In this study, we created more than 40 shale samples after a series of systematic trials with different methods to get representative synthetic shale samples. During this process, a method was developed to manufacture synthetic shale samples, which have the correct weight to density ratio and the best mix of minerals to produce a consistent media (Altowairqi et al, 2015). The target of making a mix of minerals consistent, is to make sure all the different types of minerals are mixed well and equally around the sample.…”

“…Presently our understanding of their dynamic and elastic behaviour is very limited, due to the low volume of variable organic shale samples available as well as the amount of time taken to test low-permeability samples. Experiments involving organic shale core samples can be found in a limited number of publications (Altowairqi et al, 2015;Altowairqi et al, 2013;Dewhurst et al, 1998;Dewhurst and Siggins, 2006;Dewhurst et al, 2011;Delle-Piane et al, 2011). One of the difficulties is that organic rich shales are chemically and mechanically unstable, due to the organised distribution of platy clay minerals (Zhu et al, 2011) and compliant organic materials (Vernik and Nur, 1992;Vernik and Liu, 1997;Sondergeld et al, 2000;Vernik and Milovac, 2011).…”

“…It is challenging to characterise unconventional natural gas reservoirs, because the elastic properties of shale rock vary significantly within and across such reservoirs due to various mineral composition and fabric anisotropy parameters exhibited by these organic rich shales (Altowairqi et al, 2015;Zhu et al, 2011). Presently our understanding of their dynamic and elastic behaviour is very limited, due to the low volume of variable organic shale samples available as well as the amount of time taken to test low-permeability samples.…”