Evaluation of the Rock Brittleness and Total Organic Carbon of Organic Shale Using Triple Combo
- Anshul Dubey (Selman & Associates, Ltd) | Mohamed Ibrahim Mohamed (Colorado School of Mines) | Mohamed Salah (Khalda Petroleum) | Ahmed Algarhy (Marietta College)
- Document ID
- Society of Petrophysicists and Well-Log Analysts
- SPWLA 60th Annual Logging Symposium, 15-19 June, The Woodlands, Texas, USA
- Publication Date
- Document Type
- Conference Paper
- 2019. held jointly by the Society of Petrophysicists and Well Log Analysts (SPWLA) and the submitting authors
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- 183 since 2007
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Rock brittleness and total organic carbon (TOC) are two essential parameters that are needed to evaluate unconventional reservoirs. Brittleness is a crucial rock physics property that is used to guide both completion and hydraulic-fracturing designs.
The brittle shale is more likely to be naturally fractured and more likely to respond well to hydraulic fracturing. Ductile shale, on the contrary, is more plastic, absorbs energy, and is not considered neither a good producer nor a desirable hydraulic-fracturing interval. In such cases, formation tends to heal any natural or induced fractures. Thus, intervals with high brittleness are considered a good candidate for hydraulic fracturing. However, many authors argue that this viewpoint is not reasonable because rock brittleness is not an indicator of rock strength and the current brittleness indices are based on elastic modulus or mineralogy. Brittle rock just has shorter plastic deformation, and it is not certain that it is easier to fracture brittle rock than ductile rock since brittle formation may have greater strength than ductile formation.
TOC is the measure of the total of carbon present in an organic compound and is usually used as an important factor for unconventional shale resources evaluation. In this study, we show an application of estimating total organic carbon (TOC) in a Khataba play from the triple combo logs using curve fitting. This paper also presents a brittleness model that uses the triple combo log. Logging and laboratory core testing data were collected from Khataba shale wells in Egypt. Laboratory testing was conducted to understand the complex rock mineralogical composition. Geomechanical rock properties derived from analysis of full-wave sonic logs and core samples were combined to develop sophisticated models to verify the principle of brittleness and fracability indices and to demonstrate the process of screening hydraulic-fracturing candidates. Tensile and compressive strength tests are conducted to understand rock strength better. Once the data were available, different methods were used to calculate brittleness index considering the effect of mineralogical composition and elastic moduli.
|File Size||2 MB||Number of Pages||11|