Журнал нефтяной и экологической биотехнологии

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Modelling Gelation Time of Organically Cross-linked Water-shutoff Systems for Oil Wells

Marfo SA, Appah D, Joel OF and Ofori-Sarpong G

Water production is one of the major challenges in the petroleum industry, especially brown fields and water drive reservoirs. Water production can weaken the cementation of sand grains, thereby rendering formations partially or completely unconsolidated. This in turn initiates fines migration and aggravates safety concerns. The gelation time is an important characteristic of water-shutoff systems and it is influenced by different parameters. The gelation time gives an indication of the time required for a gel to transit from free flowing fluid to solid or semi-solid gel making it difficult to pump. Organically cross-linked gels have numerous applications in the industry such as shutoff systems. They are used to control water and gas production in oil wells. The effect of cross-linker concentration, temperature and brine concentration on the gelation time of an organically crosslinked system was studied. Based on the experimental results a mathematical model was developed for predicting the gelation time of the water-shutoff system. The results showed that temperature had the highest impact on the gelation time of the water-shutoff system with an effect estimate of (-2.292). The brine concentration of the mix water recorded the lowest impact with an effect estimate of 0.2083 and the interaction between cross-linker concentration and brine concentration of mix water had neutral impact. A predictable and effective water-shutoff system has been developed with an excellent initial viscosity which can easily be pumped and applied to solve water production and its associated problems. The gelation time of organically crosslinked water-shutoff system can be optimised in water control operations using this model and the effect estimates of these parameters.