Sand Hill Fault

Fig. 13. Ternary diagram showing composition of micrite, spar and Sand Hill fault cements from the study area. The scale of the plot is at 99 mol% CaCOj. Data for fault cements from Mozley Goodwin (1995b).

Mozley, P. Goodwin, L. (1995b) Patterns of cementation along the Sand Hill Fault, Albuquerque Basin, NM implications for paleoflow orientation and mechanisms of fault-related cementation. In Characterization of Hydrogeologic Units in the Northern Albuquerque Basin. (Eds Haneberg, W.C. Hawley, J.W.). New Mexico Bureau of Mines and Mineral Resources Open-File Report, 402-C, 3-11-3-23. 

Reservoir rocks and seals work together to form a trap for petroleum. Typical traps for petroleum include hills shaped like upside-down bowls below the surface of the earth, known as anticlines, or traps formed by faults. Abrupt changes in rock type can form good traps, such as sandstone deposits next to shale deposits, especially if a sand deposit is encased in a rock that is sufficiently rich in organic matter to act as a petroleum source and endowed with the properties of a good seal. 

An often-cited case of reservoir failure occurred with the Baldwin Hills Reservoir near Los Angeles, California, in 1963. This rectangular basin had been carved on top of a hill in 1951 and rested on poorly consolidated earthen material consisting primarily of silt, sand, and clay. Pumping of oil in the vicinity had led to ongoing settling of the land. Movement of faults beneath the reservoir dam led to an abrupt loss of water, erosion of material from beneath the dam, and an abrupt breach of the dam. The sudden rush of water from the reservoir that resulted killed 5 people and caused 15 million of damage. 

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