Modeling the application of scale-inhibitor-squeeze retention-enhancing additives

The most common method for preventing scale formation is by applying a scale-inhibitor (SI) squeeze treatment. In this process, an SI solution is injected down a producer well into the near-wellbore formation. In the last few years, several publications have presented experimental results, field data, and treatment methods showing enhanced squeeze lifetime because of the use of squeeze enhancers.

The main purpose of this paper is to model the effect of SI-retention-enhancing additives. These additives are normally deployed in reservoirs where the SI shows poor retention in the formation matrix in order to reduce well interventions. In the last few years, a number of techniques to enhance the SI retention have been reported in the literature, such as precipitation squeezes using calcium and/or pH-increasing additives, use of an additive package that enhances SI adsorption by crosslinking, and the injection of nondamaging concentrations of kaolinite, calcium carbonate, and organosilane (a solids-fixation agent). The effect of the SI-retention enhancer is modeled as a function of the adsorption level of the additive.

A sensitivity study is then presented of the effect of deploying the additive in the different stages; normally, they are deployed in the preflush stage. However, the aim of this paper is to investigate how the treatment could be optimized to achieve the longest squeeze lifetime with a fixed amount of additive. An example of modeling a specific field treatment injecting organosilane is included. The results are compared with the field return profiles and clearly demonstrate the value such modeling can bring to the interpretation and design of field squeezes.