Scale Risk Assessment and Scale Inhibition Measures of Non-Metallic Pipes in Mahu Oilfield

In order to solve the scaling problem of non-metallic pipe in Mahu oilfield, the effects of temperature, partial pressure of CO₂, Ca²⁺ content and salinity on the scaling of glass fiber reinforced plastics (GFRP), thermoplastic lined GFRP and flexible composite pipes were studied through scaling test and contact angle measurement, and the scale inhibitor suitable for the field condition of Mahu oilfield was selected. The results showed that the scaling rate of the flexible composite pipe was much higher than those of the other two materials under the same conditions. The significance ranking of several factors affecting on the scale formation of non-metallic pipes was temperature >salinity>partial pressure of CO₂>Ca²⁺ content. Organic phosphonic acid scale inhibitor (MQ2) had the best scale inhibition effect, and its recommended injection dosage was 60 mg/L. Field application results showed that the scale formation in non-metallic pipes could be well controlled by lowering operating temperature and adding MQ2.