Organic bases as additives for steam-assisted gravity drainage

Abstract

Steam-assisted gravity drainage (SAGD) is a mature technology for bitumen recovery from oil sands. However, it is an energy-intensive process that requires large amounts of steam to heat and mobilize bitumen. The purpose of this work is to develop ways to enhance SAGD performance through the use of organic base additives. The research is approached from three focus areas that supplement and guide each other: characterization tests, sand-pack floods, and computational simulation. A number of key mechanisms for enhancing oil recovery were identified, high-temperature additive characterization tests were developed, and promising alkalis were tested in porous media. Simulation was employed to history-match sandpack flood production data, in order to demonstrate the effect of an additive on the oil-water relative permeability. Based on these results, it was concluded that oxygenated organic bases had the most potential for improving bitumen recovery through reducing the oil-water interfacial tension (IFT) by increasing the pH of the system. These organic bases favorably modify the interfacial energies between the immiscible oil-water phases and enable them to flow easily through the porous media during production. Sand-pack flood tests have successfully demonstrated a 10%-15% improvement in bitumen recovery, over baseline, in the presence of IFT-reducing additives. Simulation results further showed that an IFT reduction had a positive impact on SAGD performance. This work demonstrates the potential of organic bases to improve not only SAGD, but other steam injection processes. Furthermore, a number of experimental methods were developed, tried, and tested during the course of this work. Keywords Heavy oil • Steam flood • Low interfacial tension • Wettability • Enhanced oil recovery • Organic bases List of symbols k rw Water relative permeability at S w k row Oil relative permeability at S w k rwro Water relative permeability at residual oil k rocw Oil relative permeability at connate water S w Water saturation S wc Connate water saturation S orw Residual oil saturation in the presence of water Z w Water Corey exponent Z ow Oil Corey exponent

Profile Control Using Fly Ash Three-Phase Foam Assisted by Microspheres with an Adhesive Coating

“…The microsphere is composed of an internal core and a layer of coating materials (Figure 1). The internal core is made of ultralight ceramsite, with a bulk density between 1.06 g/cm 3 and 1.25 g/cm 3 . A nominal breaking rate of the ceramsite varying from 3.5% to 18% under 52MPa is recorded by the manufacturer (Beijing Qisintal New Material Co., Ltd, Beijing, China).…”

“…Steam injection has been acknowledged as one of the most effective approaches for heavy-oil exploitation [1][2][3]. Nevertheless, due to the great density disparity, steam tends to flow in the upper reservoir (the so-called "gravity override"), which aggravates as the reservoir thickness increases [4,5].…”

Clay-Sand Wettability Evaluation for Heavy Crude Oil Mobility

“…These chemicals can be obtained from vegetal oils [11][12][13] or extracted from plants over fermentation processes. [14][15][16] Another method to improve displacement efficiency is using a surfactant or alkaline solution, with concentrations up to 5 %, that changes the interfacial tension and generally produces oil-in-water emulsions that are less viscous fluids. [17][18][19] However, the fluid-rock interactions that are present in the extraction processes have to be considered.…”

A Population Balance Model for Emulsion Behavior of Alkaline Water–Heavy Oil Systems in Bulk Phase

“…Alkaline flooding has been found to be an efficient and economical enhanced oil recovery (EOR) technique for decades. − In recent years, alkalis have also been integrated with other EOR techniques such as steam-assisted gravity drainage (SAGD), − surfactant and/or polymer flooding, − and nanoparticle-assisted processes − by taking the advantages of reducing the surfactant adsorption loss, protecting surfactant against divalent ions, and reacting with the petroleum acids to form in situ surfactant . The in situ generated surfactant helps to reduce the interfacial tension (IFT) between oil and the aqueous phase, while amphiphilic components (e.g., resins, asphaltenes, and natural petroleum acids) in crude oil strengthen the stability of a water–oil emulsion. , The lower the IFT is, the more easily the crude oil could be emulsified with water. , Once an O/W emulsion is formed, the mobility of the oil phase can be greatly improved .…”