Evaluation of Barium Sulfate Scale Inhibition Using Relative Permeability Modifier Polymers as Adsorption Enhancer for Mature Offshore Well Treatments in Campos Basin, Brazil

Abstract

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.

Investigating the Effectiveness of Phosphonate Additives in Hindering the Calcium Sulfate Dihydrate Scale Formation

“…[5][6][7][8] There are various types of minerals that form scales. Among these, calcium carbonate 9,10 , barium sulfate 11 , magnesium hydroxide 12 , silica 13,14 , and calcium sulfate 15,16 are frequent. In the calcium sulfate system, calcium sulfate dihydrate (gypsum, CaSO4•2H2O) commonly precipitates in industrial systems 17 , and its formation and solubility are controlled by different parameters such as temperature, supersaturation, and impurities.…”

Mechanistic Aspects of Polymeric Relative Permeability Modifier Adsorption onto Carbonate Rocks

“…However, the literature and the experimental observations indicate that the effect of the RPM is the major contributor. 17,21,27 In addition, many of these factors have been minimized, for example, the hysteresis effect has been minimized by stabilizing the fluid flow. The rocks are based on carbonates so there is no clay present so the production of fines is minimized.…”

Molecular Dynamics Simulation of Calcium Sulfate Nucleation in Homogeneous and Heterogeneous Crystallization Conditions: An Application in Water Flooding

“…The challenge of inorganic scale formation would affect the production efficiency in many geological and industrial processes. − Scaling has been recognized as one of the most costly oil industry challenges when mineral salts deposit from an aqueous supersaturating phase on the surfaces. , This phenomenon has been reported in numerous cases for both upstream and downstream operations. In downstream processing, inorganic scales can be formed along all water flow lines in different equipment such as pipe, valve, and heat exchanger that affects the efficiency and lifetime of the equipment. − Moreover, during oil and gas production from the subsurface, the inorganic scales result from the water flooding process is more challenging as they deposit in a very tiny pore opening of the tight rock, causing formation damage.…”