In many mature offshore fields, high water cuts and potential scale deposition are some of the toughest challenges operators need to face. Two common practices used to deal with these challenges are relative permeability modifiers (RPM) polymer injection and scale inhibitor squeeze treatments. Even though many fields face these two challenges simultaneously, little is known about concomitant application of these treatments. In this paper, the effect of applying RPM polymers prior to inhibitor squeeze in the effectiveness of the last treatment is evaluated for sandstone rocks of Campos Basin, Brazil. Sequential laboratory injections in Campos Basin rocks of commercial cationic and anionic polyacrylamide and polyaluminum chloride (PAC) as cross-linking agent were employed prior to the injection of a commercial organophosphonic acid type inhibitor for barium sulfate scale. It was found that the polymers employed are capable of reducing the permeability of porous media to water and increasing the retention time of the scale inhibitor simultaneously. The tests also indicated that the inhibitor's longer retention time is associated with the interaction with an outer cationic layer of the cross-linking agent. The adsorption isotherms were calculated and compared with Langmuir, Freundlich, Sips, and Toth models, the last two being the most accurate in representing the adsorption system for these tests.

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This article summarizes initial efforts on the evaluation of the joint action of chemical inhibition and magnetic field to maximize the potential of scale mitigation in downhole conditions. This strategy is seen as a promising way to enhance flow assurance reliability in high cost deepwater wells where workover jobs are very expensive. This strategy is being considered as a good option for downhole applications where portions of the wellbore are not assisted by chemical injection or even as a redundancy which can attenuate effects of chemical injection failure. The calcium carbonate scale in the oilfield is typically controlled by chemical inhibitors, in several types and concentrations, depending on the saturation index related to the application. A magnetic field has the potential of retarding scaling of inorganic salts in oil production/water treatment systems. A preliminary assessment of the association of magnetic field and inhibitors to postpone carbonate scaling has been evaluated, based on tube blocking test method and two saturation indexes levels (2.8 and 3.03 – SSP Norm Scale). The reactor, with nominal diameter of 1/8", was operated under the total flow rate of 52 mL/min. (Re ≈ 800), the pressure of 50 kgf/cm2, temperatures of 40, 60, and 80 °C, using hydroxymethyl amino-di(methylene phosphonic acid) inhibitor type at different concentrations. The magnetic field employed was 1,6 Tesla. Results indicate that at given conditions, expressive delay can be achieved with the combination of the two techniques, while in other situations the system may need redesign. This study reveals an interesting potential of coupling two different mitigation strategies aiming different applications, such as spacing the necessity of squeeze treatments and optimizing surface treatment.

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