Petroleum applied the first massive hydraulic fracturing (also known as high-volume hydraulic fracturing) treatment in the world to a well in Stephens County, Oklahoma in 1968. The treatment injected half a million pounds of proppant into the rock formation. In 1973, Amoco introduced massive hydraulic fracturing to the Wattenberg Gas Field of the Denver Basin of Colorado, to recover gas from the low-permeability J Sandstone. Before massive hydraulic fracturing, the Wattenberg field was uneconomic. Injected volumes of 132,000 or more gallons, and 200,000 or more pounds of sand proppant, succeeded in recovering much greater volumes of gas than had been previously possible. In 1974, Amoco performed the first million-pound frac job, injecting more than a million pounds of proppant into the J Sand of a well in Wattenberg Field. The success of massive hydraulic fracturing in the Wattenberg Field of Colorado was followed in the late 1970s by its use in gas wells drilled to tight sandstones of the Mesaverde Group of the Piceance Basin of western Colorado. Starting in the 1970s. thousands of tight-sandstone gas wells in the US were stimulated by massive hydraulic fracturing. Examples of areas made economic by the technology include the Clinton-Medina Sandstone play in Ohio, Pennsylvania, and New York; the San Juan Basin in New Mexico and Colorado; numerous fields in the Green River Basin of Wyoming; and the Cotton Valley Sandstone trend of Louisiana and Texas. Coalbed methane wells Coalbed methane wells, which first began to be drilled in the 1980s, are commonly hydraulically fractured to increase the flow rates to the well. Hydraulic fracturing is commonly used in some coalbed methane areas, such as the Black Warrior Basin and the Raton Basin, but not in others, such as the Powder River Basin, depending on the local geology. Injected volumes tend to be much smaller than those of either tight gas wells or shale gas wells; a 2004 EPA study found a median injected volume of for coalbed methane wells. Horizontal wells The combination of horizontal drilling and multistage hydraulic fracturing was pioneered in Texas’ Austin Chalk play in the 1980s. Stephen Holdich, head of the Department of Petroleum Engineering at Texas A&M University, commented: “In fact, the Austin Chalk is the model for modern shale development methods.” The Austin Chalk play started in 1981 with vertical wells, but died with the decline in the oil price in 1982. In 1983, Maurer Engineering