Innovative Method to Mix Corrosion Inhibitor in Emulsified Acids

Abstract

Acid in oil emulsions stimulate carbonate formation of limestone and dolomite. These emulsions consist of internal inhibited acid phase and an external hydrocarbon phase mixed with an emulsifier. In this current technology, the corrosion inhibitor is dissolved in the acid phase and encapsulated by hydrocarbon in the outer phase. The facts that the corrosion inhibitor is inside the emulsion will retard it from dispersing on metal surface of the tubing to create a metal protective film. In this paper, a method is proposed where the corrosion inhibitor is replaced from being in the internal phase to be in the external phase of the emulsion. This situation will allow the corrosion inhibitor to directly disperse onto the tubing metal surfaces to form the protective film required to prevent the tubing from any acid attack. Acid in oil emulsion with corrosion inhibitor being in the external phase of emulsion was successfully created in the lab and resulted in a much better thermal stability at room and reservoir conditions. In this lab study, thermal stability of emulsion with corrosion inhibitor in the external phase resulted in more stable emulsion than those with corrosion inhibitor in the internal phase. At reservoir temperature of 248oF emulsions with corrosion inhibitor in the external phase acid start to separate after 60 minutes and at 150 minutes was completely separated. Emulsions at same conditions with corrosion inhibitor in the internal phase acid start to separate after 30 minutes and at 110 minutes were completely separated from hydrocarbon phase. When corrosion inhibitor removed completely from the emulsion, it start to separate at 140 minutes and at 180 minutes separation was only 20%. Corrosion inhibitor being in the external phase will enhance emulsions retardation and hence deeper penetration in the reservoir. In addition this new method will protect the well tubing and stimulation equipment much better than before. Introduction This paper provides a method of enhancing the corrosion inhibition of well tubing while using an acid-in-oil emulsion downhole in a hydrocarbon recovery or delivery system. In addition, this paper provides a method for acid stimulation of a carbonate formation while simultaneously protecting the well tubing more efficiently. Acid-in-oil emulsions are typically used to stimulate or enhance hydrocarbon production in existing carbonate reservoir rock formations, such as limestone, dolomite or calcareous-magnesium. Typically, the emulsified acid enters the formation and where employed successfully creates a barrier causing the acid to release slowly at a distance from the wellbore. The reaction of the released acid with the formation rock takes place simultaneously at different places inside the formation, resulting in channels that are joined together to form continuous wormholes. When pumping the acid-in-oil emulsions through steel tubing and piping, a corrosion inhibitor is usually added to reduce the corrosive effects of the acid. In operation, the corrosion inhibitor coats the steel surfaces as the emulsion is pumped into the wellbore and the surrounding rock.

Mimicking Bone Chemical Composition Using Economical Materials for X-Ray Imaging Quality Assurance and Educational Purposes

“…The mixing process of four (10 cm-wide) shakes per second for 1 minute mixed all solid materials homogeneously. These materials were mixed with Safa (branded) water (Ca-Na-HCO 3 -C1-SO 4 ) [7]. The major ion concentrations and physical properties of the water (as indicated by the manufacturer) are illustrated in Table 2.…”

A Review on Use of Emulsified Acids for Matrix Acidizing in Carbonate Reservoirs

“…Water in oil emulsions provide better retardation due to the low diffusivity created by the oil phase around acid droplets, which allows for minimum acid volume contact with the rock–tubular surface. Thus, most research ,,− ,,,− , has adapted W/O emulsions due to their desirable retardation effect and corrosion inhibition in comparison to O/W emulsions, , as depicted in Figure .…”

“…Beyond critical micelle concentration, droplet size does not decrease; however, in the case of pickering agents, this can lead to increased stability with a relatively lower amount than that used for surfactant. Moreover, macroemulsions are favored for matrix acidizing over microemulsions, which provide sufficient stability with ample acid volume. − The use of a pickering emulsion and a hybrid emulsifier (combination pickering particles and surfactants or polymers) greatly minimizes the emulsifier concentration while forming a strong structural network, which provides enhanced stability. ,, …”

“…For instance, acid type and concentration can reduce the inhibition ability of a corrosion inhibitor; similarly, an increase or decrease in the inhibitor concentration can have an effect on the stability provided by the emulsifier and vice versa. ,,, It is best to keep the additives away from one another by placing them on opposite sides of the oil phase, which reduces their interaction, enhances the life span of the emulsion, and in certain cases increases certain capabilities of the emulsion. For example, Al-Zahrani, instead of just focusing on the concentration of inhibitors and emulsifiers, changed the placement of the corrosion inhibitor in the emulsion phases by placing it as an external phase while the acid was encapsulated by oil. This allowed the inhibitor to have direct contact with the well tubing.…”

Application of emulsified acids on sandstone formation at elevated temperature conditions: an experimental study

“…Hence, the delayed nature of emulsified acid has attracted the attention of the oil and gas industry as it could decrease the reaction rate, reduce the contact between acid and well tabular and minimise corrosion issues that is related to well integrity, cost and above all issue associated with safety and environment. In carbonate matrix acidizing using emulsified acid, longer conductive flow paths or "wormholes" are induced, thus improving the permeability and productivity of the reservoir (Sabhapondit et al 2012;Al-Zahrani 2013;Fattah and Nasr-El-Din 2008). Experimental studies and real field application has indicated that emulsified acid can improve carbonate porosity and permeability while minimizing corrosion issues (Sayed et al 2013;Zakaria et al 2012;Navarrete et al 1998;Al-Anazi et al 1998).…”