Final answer:
Hydraulic fracturing, or fracking, is the standard workover procedure used to clear clogs from loose sand in unconsolidated sandstone reservoirs, utilizing a high-pressure mix of water, sand, and chemicals.
Step-by-step explanation:
When loose sand from unconsolidated sandstone reservoirs clogs the bottom of the well, the type of workover that is typically performed is hydraulic fracturing (also known as fracking). This process involves injecting water, sand, and chemicals under high pressure into the well. The pressurized mixture creates fractures in the rock and the sand particles help keep these fissures open, allowing for oil or gas to flow more freely up the well.
Over time, such procedures may become increasingly necessary as the easier-to-extract deposits are depleted, forcing engineers to find ways to extract oil from tight sandstone or other low-permeability rock formations. Hydraulic fracturing is especially important in 'tight gas' recovery, where natural gas is trapped in formations that may not allow it to easily flow out.