Petroleum production involves complex systematic engineering. The key point of petroleum production engineering is to keep the water well and the oil well unblocked, so that oil is continuously extracted out while water is continuously injected in. Unfortunately, the oil well and the water well are blocked very often. There are four kinds of blocking substances: inorganic salts (such as carbonates, silicates, etc.); biological coenobiums; ferrous sulfide blocker in oil layers produced by steel corrosion induced by the biological coenobiums; and high molecular polymers used in well drilling, well pressing, well repairing, press-fraction and water packing-off in the tertiary oil extraction procedures. These high molecular polymers damage the permeability of the subterranean in different degrees and form blocking.
At present, the acidic solution used in acidification block-removing technology is corrosive to minerals in the subterranean and inorganic blocks in different degrees; this corrosion can release mostly permeability damage induced by inorganic substances, but it is less effective, or not effective to blockings induced by polymers and microorganisms.
According to the disclosures of some literature, chlorine dioxide has already been used to remove blockings in oil fields at the end of the 1980's in the USA and other countries. It has obtained outstanding effects on oil output increase and block-removal. In China, many oil field companies and research institutes investigated block-removal using chlorine dioxide in oil fields in the 1990's. However, due to the danger of explosion induced by the leak of chlorine dioxide, damage to the human body, and corrosion of equipment and pipes in oil fields induced by the strong oxidization of chlorine dioxide, chlorine dioxide has not been applied in real oil fields yet.
USPTO Backgrounds
USPTO Backgrounds