Providing a Method for Predicting the Scale Formations Related to Changes in Temperature and Pressure of Production Wells Using the Marching Algorithm: A Case Study of One of the Wells in the Southwest of Iran

The purpose of this research is initially to model the pressure and temperature profiles along with other properties of the reservoir production fluid such as density, viscosity, and different in situ useful parameters in the well using the Beggs and Brill method as well as the marching algorithm. As a result, we can be aware of scale formations anywhere in the well at any time without the use of particular physical and inside of the well tools without spending a lot of economic costs. After estimating the thermodynamic and physical conditions of the well fluid, the physicochemical state of the producing fluid in saturated, supersaturated, and undersaturated states forms problematic scale deposits using calculations of concentration changes and saturation index using Oddo and Tomson method. Finally, using mathematical models, we investigate and record the potential for deposition, critical depths, and prone to scale deposition. Although deposits that stop the production of wells may be in porous media, this study was performed only inside the well and the tubing. The results of modeling on one of the oil wells under the supervision of the national company for southern oilfields as a case study showed that with an increase in depth from the surface, the saturation indexes for hemihydrate calcium and strontium sulfate scales along the well in almost all the depths are negative. As a result, it can be said that there is no possibility of the formation of these scales at different depths of the well. The same is true for the scale formation of hydrated calcium sulfate (gypsum). In addition, near the surface, the saturation index of this scale is positive and slightly larger than zero, which indicates the possibility of gypsum deposition in this depth range. Finally, the saturation index for anhydrous calcium sulfate (anhydrite), barium sulfate, and calcium carbonate (calcite) scales have always been positive, which indicates the probability of the formation of these scales in the well.