Study On The Preparation Of The Slow Releasing Inhibitors For Salt Deposition

Precipitation of sodium chloride is a troublesome problem in many oil wells, which is extremely undesirable since it causes deposits which build up in conduits and in the formation itself. Such deposits often interfere with the flow of oil being produced from the formation. So the oil producing ability was decreased. In general, treating with fresh water has been used to remove sodium chloride deposits. However, such treatment is quite impractical when only a limited amount of fresh water is available or when the ambient temperature is below the freezing point of water. Since a large number of oil producing formations are located in areas where only small amounts of fresh water are readily available, it has also been very expensive and economically unattractive to perform fresh water treatments. We developed a kind of sodium chloride inhibitor with slow releasing rate, for the purpose of inhibiting salt deposition, increasing the yield of oil well and simplifying the operating process. It' s an effective method of inhibiting salt deposition by throwing chemical inhibitor to the oil well. However it has shortcomings of feeding inhibitor frequently and short period of validity. So there is a good foreground and research worthiness to develop a kind of inhibitor with slow releasing rate.The chemical salt inhibitor operates by two ways: one is increasing the salt' s solubility to inhibit the solution from crystallizing salt, and the other is altering the structure of the crystals from compact cube configuration to loosen and smash configuration, so it is easier to be cleared and brought out by the fluid. It is showed by experiment that sodium ferrocyanide is a good inhibitor. The concentration of sodium ferrocyanide influence the solubility of sodium chloride evidently, commonly there is a good effect when the concentration is 60～100ppm. Sodium ferrocyanide is an inorganic salt with good solubility, so we must try to slow its release rate.