Deep-Well Acid Disposal—Planning and Completion1
Because of fhe magnitude of damage wrought to our natural resources, pollution control and environmental protection are a vital part of our everyday living. Pollution of air, land, and surface water has led to the use of subsurface disposal (storage) of waste effluents. The federal government and the individual states are continually passing new laws governing deep-well disposal. Feasibility studies are mandatory and must include an analysis of fhe disposal reservoirs and a detailed geologic study to determine the presence of faults or abandoned wells that could be a source of contamination of potable waters.
Many of the cementing procedures used in the oil industry are also used in disposal wells; however, added precautions must be taken in the design of the casing and injection strings. These precautions include the use of materials that are resistant to chemical attack, such as special alloys and fiberglass. Oil-well cements may be used in wells where the effluent is organic—e.g., weak organic acids, sewage waste, ferric chloride, and chemically treated effluents having a pH of 6 or above. A formulation of cement and liquid resin will resist attack from dilute acid solutions. The latest development in resin compositions is a blend of epoxy resin and an inert filler. This resin system has shown considerable promise for use in cementing disposal wells. It is resistant to concentrated acidic and caustic effluents and provides excellent bonding properties to the tubular goods.