Equilibrium Modelling of Interactions in DETPMP-Carbonate System

Mahdi Kalantari Meybodi, Oscar Vazquez, Kenneth S. Sorbie, Eric J. Mackay, Khosro Jarrahian

Research output: Chapter in Book/Report/Conference proceedingConference contribution


Scale inhibitor (SI) squeeze treatments are widely used for the prevention of inorganic scale deposition in oil and gas production operations. This may be an expensive operation and its efficiency depends on the degree of SI retention in the formation. Carbonate formations are known to be highly reactive, where the SI retention is driven by both adsorption and precipitation of SI and SI-Ca/Mg complexes. To design and carry out this type of squeeze treatment, a comprehensive model capable of simulating SI retention in carbonate formations is required. In this study, a model has been developed to fully characterize the retention of DETPMP in a carbonate system. This model considers all the equilibrium reactions coupled with precipitation and adsorption processes to simulate the equilibrium of a DETPMP-Calcite-brine system containing free Ca2+ and Mg2+ cations. To equilibrate this system, the following coupled reactions were considered: (i) the full aqueous carbonate system, (ii) SI speciation by dissociation (SI is considered as a weak n-poly acid, HnA), (iii) SI impurities and their reactions, (iv)SI-Ca and SI-Mg complexation, (v)the associated adsorption and precipitation of the SI/Ca/Mg complexes. These reactions may be coupled together through the equilibrium equations, the mass balance of base species and the system charge balance. After some algebra, the system of equations is reduced and solved by Newton Raphson to find the concentration of key primary species from which the concentration of all other species is calculated and the equilibrium of the entire couple system is characterized. In the entire system, there may be up to ~100 species involved in the chemical equilibrium equation set. The adsorption process is characterized by an adsorption isotherm, Γ(C), which can be a reversible process. In the examples presented, the adsorption is considered to proceed in both directions of adsorption and desorption. Precipitation (denoted Π) is coupled with the adsorption (and the rest of the system) to satisfy the SI solubility by removing further SI from the solution, if required, through the complex SI species that may physically precipitate. Finally, the proposed model was validated against coupled adsorption-precipitation experiments. The results showed very good agreement between the model and experiments and confirmed the reliability and validity for various conditions and DETPMP concentrations.
Original languageEnglish
Title of host publicationSPE Oilfield Scale Symposium 2024
PublisherSociety of Petroleum Engineers
ISBN (Electronic)9781959025467
ISBN (Print)9781959025467
Publication statusPublished - 5 Jun 2024
EventSPE Oilfield Scale Symposium 2024 - Aberdeen, United Kingdom
Duration: 5 Jun 20246 Jun 2024


ConferenceSPE Oilfield Scale Symposium 2024
Abbreviated titleOSS 2024
Country/TerritoryUnited Kingdom


  • asphaltene inhibition
  • sedimentary rock
  • carbonate reservoir
  • complex reservoir
  • geology
  • remediation of hydrates
  • scale inhibition
  • rock type
  • hydrate inhibition
  • geologist
  • Production Chemistry
  • Metallurgy and Biology
  • Unconventional and Complex Reservoirs
  • inhibition and remediation of hydrates
  • Scale
  • paraffin / wax and asphaltene
  • carbonate reservoirs


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