Study on Scaling Formation Characteristics and Produced Liquid Properties in Oil-Wells of ASP Flooding

Abstract

Strong base ASP flooding technology can improve oil recovery by 20%, but the lifting system exists serious scaling problems which cause pump detection period shorter. The main composition of the scale are organisms (heavy oil is in majority), carbonates and silicates. The content of each component is closely related to pH value. With high pH value, the main composition of the scale is silicate. With low pH value, the main composition of the scale is carbonate. The results of analysis of the relationship between scale composition, scaling position and depositional sequence showed that the content of silicate gradually increased from top to down in shaft while the carbonate decreased. In the process of scale deposition, carbonate scale emerged at first and then it provided attachment points and crystal nucleus for the silicate. The rough surface of carbonate scale increased the friction between the fluid and the wall, it promoted the formation of silicate. Statistically analyze the properties of pH value, alkalinity, calcium, magnesium, silicon, polymer, viscosity, surfactant, fluid yield, water content in produced liquid and their influences on scaling in the injection-production period. Establish the prediction basis using the pH value as primary and ion content as supplement for the problems of mechanical production well scaling. In the period of carbonate scaling (pH10.5), the process slowed down. The coincidence rate was 93.9% after pilot tests. It provided a basis for taking corresponding measures to inhibit scale formation.