Compaction shale

Severe settlements may take place in low-grade compaction shales. Conversely, uplift frequently occurs in excavations in shales and is attributable to swelling and heave. Rebound on unloading of shales during excavation is attributed to heave due to the release of stored strain energy. The greatest amount of rebound occurs in heavily overconsolidated compaction shales. Sulphur compounds frequently are present in shales and mudstones. An expansion... 

Not all shales are suitable for the excavation of underground caverns in that soft compaction shales present difficulties in terms of wall and roof stability. Caverns may also be subject to floor heave. Caverns can be excavated in competent cemented shales. Not only do these possess low permeability, they could also adsorb ions that move through it. A possible disadvantage is that if temperatures in a cavern exceeded 100°C, clay minerals could lose water and, therefore, shrink. This could lead to the development of fractures. 

Severe settlements may take place in low grade compaction shales. As a consequence, such sites are generally developed with earth dams, but associated concrete structures such as spillways will involve these problems. Rebound in deep spillway cuts may cause buckling of spillway linings, and differential rebound movements in the foundations may require special design provisions. 

Compaction shale or other highly argillaceous rock in Soft rock 8-12 10... 

Fig. 11. Results of a mathematical model of organic acid generation in a compacting shale for three thermal gradients at a burial rate of 333m/Ma. Plot shows relative generation rate versus burial depth. Higher thermal gradients result in peak generation rates at shallower depths and after less geologic time...

Compactible (shale-prone) low-energy sediments also t rpical of last stages of graben fill. 

Solids. Proper handling and disposal techniques can obviate potential problems associated with the soHd waste-retorted shale. Retorted shale disposal and revegetation have posed no adverse environmental impacts at the Unocal Parachute Project (62). EarHer studies carried out using Paraho and Lurgi retorted shales indicated that these materials behave as low grade cements (63,64) and can be engineered and compacted into high density materials (Pig. 11) and water impervious stmctures (Table 15). 

Table II shows the result of compaction experiments with Glen Rose Shale. Column 2 gives the equilibrium NaCl concentration of the solution before the compaction experiment. Column 3 gives the anion-free water calculated as shown in Appendix I. Column 4 gives the amount of the bulk solution which has the NaCl concentration given in Column 2. Column 5 gives the total amount of fluid flowing out of...

Table II. Compaction Experiments of Glen Rose Shale...

COMPACTION TEST CURVE CUW AND SHALE CURVE KH POINT VALUE Clay and silty clay Pelagic clay Terrigenous silty clay Clay with volcanic shard relicts COMPOSITE CURVE... 

If, as has been previously stated, the shale layers become compacted to near 0% porosite at lKm depth, the petroleum substances will use the released constitutional water held in the montmorillonites in order to migrate to any great extent. This does not normally occur until... 

The plant precursors that eventually formed coal were compacted, hardened, chemically altered, and metamorphosed by heat and pressure over geologic time. It is suspected that coal was formed from prehistoric plants that grew in swamp ecosystems. When such plants died, their biomass was deposited in anaerobic, aquatic environments where low oxygen levels prevented their reduction (rotting and release of carbon dioxide). Successive generations of this type of plant growth and death formed deep deposits of unoxidized organic matter that were subsequently covered by sediments and compacted into carboniferous deposits such as peat or bituminous or anthracite coal. Evidence of the types of plants that contributed to carboniferous deposits can occasionally be found in the shale and sandstone sediments that overlie coal deposits. 

When pressure is applied to a mass of irregular particles confined in a chamber, the particles tend to consolidate and reduce the porosity. A marked decrease in porosity has been observed with regard to oil sands and shales far below the surface of the ground. In this connectibn, A thy (1930) has shown that the porosity of compact material below the earth s surface is given by the formula ... 

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