Calcium Carbonate Scale Considerations: A Practical Approach

Abstract

ABSTRACT Calcium carbonate scale, the most common oil field scale, normally forms from three-phase fluid systems at various downhole locations. The basic scale formation mechanism of CaCO3 in oil field operations was explained in a recent publication [1]. However, only the very basic model considerations and only a few field application details were given in this recent publication related to CaCO3 scale modeling. Most practical field applications of the CaCO3 scale modeling efforts were ignored. In this present paper, we elaborate on the same mechanisms of CaCO3 scale formation in a typical oil field emphasizing some of the more practical aspects of this scale modeling for field operators. None of the theoretical but only some very practical aspects of this scale formation are stressed in this present paper. The outcome of some scale model runs is used to show some practical field applications of any serious model efforts. An attempt is made to show some field problems related to this common type of oil field scale and how a proper modeling can overcome some of these problems. A series of different produced fluids are used in fifteen (15) examples (representing 15 different wells) to illustrate the complexity and intricacy of various CaCO3 scale formations in a hypothetical oil field. This paper is a logical follow-up of a recently issued SPE paper [1] and is mainly written for a practicing petroleum engineer who is concerned mainly with practical field operations. Therefore, all of the pertinent thermodynamics and other basic physical and chemical correlations are kept at a bare-bone minimum. Instead, we are stressing the more practical aspects of fighting CaCO3 scale in a "typical" oil field based on some model considerations and some actual calculations. Any theoretical and any serious computational considerations are deemphasized.