preview

Shale Rocks

Decent Essays

Shale is the most common sedimentary rock. It was deposited and formed by squeezing excess formation water and mineralogical transformations at different temperatures and pressures. Caprocks are essentially defined as low permeability formations, and sometimes, but not necessarily, with low porosity. More than 60% of effective seals for geologic hydrocarbon bearing formations as natural hydraulic barriers constitute of shale rocks. Shale rocks are predominantly composed of clay such as kaolinite, montmorillonite and illite. They might also have other silica and carbonate based minerals that contribute to their geomechanical strength. In 1965, D. Shaw and C. Weaver documented the average mineralogical composition of shale from three hundred …show more content…

Caprock integrity failure can cause leakage and containment incidents. Currently, there are more than 400 underground storage sites in the United States, including natural gas storage, oil and gas waste disposal, industrial hazardous and non-hazardous waste disposal, and municipal sanitation waste disposal. So far, there are no documented cases of fully remediating a leak in a caprock in either a natural gas storage or waste injection project. This makes preventing the leakage becomes essential, because most of the time, leaks could have been avoided through proper and thorough geologic characterization of the caprock [Bruno, et al, 2014]. The integrity of shale caprock relies on the geomechanical properties of the rock, and it has effects on the quality and quantity of the gas/hydrocarbons beneath and within it. Potential loss of caprock integrity is commonly due to tensile fracturing, fault activation, and wellbore failure in the caprock. Understanding the microstructure and mechanical properties of the shale caprocks helps to maintain its integrity, predict the potential risk and prevent the failures from

Get Access