Experiment Study On Evaluation Of Scale Inhibitors

In this paper, studies were carried out on the problem of CaCO3and CaSO4crystal in oil and gaspipelines, which is in the process of oil field development. It was difficultly to be removed withconventional chemical and physical methods. This research aims at the scale inhibitor of PESA,PBTCA, HPAA and DTPMPA, comparing to the scale inhibitions efficiency under severalconditions which is the amount of inhibitor, cation concentration, anion concentration, reactiontime, water bath temperature, the value of pH. In addition, we research the optimal experimentalconditions of four scale inhibitors, using orthogonal experiment. Finally, scale inhibitor wascombinated in order to improve the inhibition effects of PESA. According to the experiment, thefollowing conclusions can be deduced from the tests:(1) PBTCA is a good inhibitor on calcium carbonate scale. Its scale inhibition efficiency improvesif its concentration in aqueous system increases, it is found that they have good thermostability and can be used in oilfield water system with high pH、high concentration of calciumand alkalinity in a certain close. The high scale inhibiting ability can still be remained evenafter staying in high temperature for a long time; In addition, PBTCA is also a good inhibitoron calcium sulfate.(2) The PESA, a green and environment-friendly scale inhibitor, which the capacity on resitanceto hardness, alkali and high temperature is not ideal.(3) In the orthogonal experiment method, the optimum inhibition experiments conditions in PESAare: scale inhibitor was4mg/L, reaction time T was6h, water bath temperature was60℃and the value of pH was8; those in PBTCA are: scale inhibitor was4mg/L, reaction time Twas15h, water bath temperature was60℃and the value of pH was7; those in HPAA are:scale inhibitor was4mg/L, reaction time T was8h, water bath temperature was50℃andthe value of pH was8; equal to DTPMPA are: scale inhibitor was3mg/L, reaction time T was8h, water bath temperature was50℃and the value of pH was7.(4) To increasing the inhibition efficiency of inhibitors, polyepoxysuccinic acid (PESA) andPBTCA or HPAA is combinated. Some different formulating of recipes of combinated scale inhibitors is prepared. The scale inhibition effect of the combination of PESA and PBTCA atthe mass ratio of2:1was better than that of either PESA or PBTCA alone, this case appear toPESA-HPAA at the mass ratio of3:1. The test of scale inhibition properties of the combinatedscale inhibitors indicates that the cominatio has excellent inhibition effect on the CaCO3inoilfield water system.