Faulting and land subsidence from ground-water and hydrocarbon production, Houston-Galveston, Texas.

Land subsidence in Harris and Galveston Counties, Texas, results cause of land subsidence, subsidence and faulting are also associated with at least six oil and gas fields: South Houston, Clinton, Mykawa, Blue Ridge, Goose Creek, and Webster fields. The two-county area is interlaced by active surface faults with topographic escarpments and surface faults which control drainage patterns and create subtle photographic linear patterns, but which exhibit no topographic escarpments. Fluid production activates a given fault by differential compaction of the sediments on either side of the fault. The faults appear to be partial fluid barriers which compartmentalize land subsidence. The Texas City area is an example of a subsidence compartment where subsidence has been restricted by growth faults. Correlation of electric log data from boreholes across the faults indicates as much as 21 m of displacement of sand beds within the Chicot aquifer. This much offset of permeable beds is considered sufficient to create partial hydrologic barriers.