Simulation of inorganic scales using UTCHEM reservoir simulator

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2011-08

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Abstract

Scale deposition, either in the formation or inside the tubing, is a serious problem that can affect the productivity of oil fields. Production sustainability depends on the successful implementation of scale management strategies prior to developing new fields. Such strategies should involve tools capable of addressing the risks of developing scales during the production stage as well as determining the outcomes of possible remediation jobs in the future. UTCHEM, a multi-compositional flow model, was used in this work to present a comprehensive study that includes both precipitation and remediation scenarios. Although there are different mechanisms prompting the deposition of mineral scales, barite and calcite were selected primarily to simulate the effect of mixing incompatible water compositions; an issue that is usually associated with seawater injection. Equilibrium state calculations were carried out using a geochemical model (EQBATCH) to verify the incompatibility of the injection water with the formation water. In this work, we show the evolution, distribution, and remediation of solids over time for several hypothetical cases. The quantity of deposits in the near-wellbore region was found to be less at a highly heterogeneous reservoir model in contrast to the amount precipitated in homogenous reservoirs. This could be critical to wells productivity in the long-run since much of the drop in reservoir pressure occurs near the wellbore. The predictive ability of UTCHEM was extended to include simulating the removal of carbonate scales using a chelating chemical. The optimization of the injected treatment can be achieved mechanically through adjusting the well spacing (during the initial stages of field development) or through adjusting the concentrations of active components in the remediation fluids. The model provides a valuable tool that helps planners to predict scaling-related issues ahead of time, and subsequently to determine the economic viability of the project. This work serves as an opportunity to re-assess this simulator and allows for further work to enhance its capabilities.

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