Oil and Gas at Your Door? (2005 Edition) - Earthworks

IMPACTS ASSOCIATED WITH OIL AND GAS
Conservation Division has been investigating contamination in two regions where there is oil and
gas development. Out of 734 cases of soil or groundwater contamination statewide, 444 were
at oil or gas field production locations. 273
In New Mexico, about half of all exploration and production wastes (other than produced water and
drilling muds and cuttings) are disposed in pits, about 45% are diverted to oil “reclaimers,” and
the remainder of the wastes are buried on-site. 274
These disposal methods are typical for the industry. In addition to pit disposal and burial, landfarming
(the process of spreading waste oil on soil) is a standard industry practice for disposing
of hydrocarbon wastes. In many jurisdictions, oil companies may use a designated area for
spreading oil or hydrocarbon-contaminated soils, as long as the land is not going to be used for
agriculture. 275 Landfarming may involve the bioremediation of the soil, to decrease the levels of
hydrocarbons. To achieve bioremediation, hydrocarbon-digesting microbes found naturally in
soil are enhanced with fertilizers and moisture to degrade the material. The site is tilled periodically
and watered to maintain proper amounts of air and moisture. 276
Many oil and gas operators choose to send hydrocarbon wastes such as tank bottoms to commercial
oil field waste disposal facilities, or reclaimers. The crude oil reclamation industry recovers
marketable crude oil and other hydrocarbons from produced water, tank bottoms and other
oily wastes that are generated by the production of oil and natural gas. Marketable crude oil is
recovered from the waste materials by simple thermal and/or physical processes (e.g., heat and
gravity separation). As with on-site waste pits, these off-site facilities pose a significant risk to
migratory birds and other wildlife because they use large evaporation ponds to dispose of and
treat oil and gas wastes. Commercial facilities that dispose of wastewater through deep well
injection generally do not pose a risk to wildlife, but may pose a threat to groundwater
FIGURE I-33. LEAKING
TANKS CAN THREATEN
GROUNDWATER. Note the
hydrocarbon stains on the
soil.
resources. 277 I-57
Well Blowouts
A well blowout is defined as the uncontrolled flow of fluids from a well bore. These fluids, which
include hydrocarbons, produced water, drilling fluids and others, can contaminate soils surrounding the
well bore, seep into groundwater, and flow into nearby water courses.
Most commonly, a blowout occurs when there is insufficient pressure in a well bore to control subsurface
pressures. During drilling, completion, or plugging and abandonment operations, proper well-bore
pressure control is the key to preventing blowouts; the primary method is through hydrostatic pressure,
which is created when a well is filled with fluid (e.g., drilling mud). 278
According to the California Department of Conservation, there are three main causes of blowouts during
drilling operations, all stemming from human error: 1) failure to maintain adequate drilling fluid
weight; 2) failure to keep the hole full of drilling fluid; and 3) failure to prevent swabbing. These categories
accounted for about 55 percent of the blowouts that occurred in California from 1950 to
1990. 279
Between the years 1950 and 1990 there were 101,578 oil and gas wells drilled in California. During
this period there were 135 blowouts from onshore operations (52 during drilling; 17 during completion;
10 during plugging and abandonment; 61 during other well operations).
• Blowouts lasted anywhere from a few minutes to 13 days
• Materials that were spewed from the wells during the blowouts included: oil, gas, mud, rocks, sand,
gravel, water, saltwater, steam, and casing and tubing parts.
• There were injuries or deaths associated with 28 of the blowout incidents. In total, there were
seven deaths and 52 injuries reported. 280