Overview: Heavy Oil (April 2006)
Authors: Kovscek Tony 
Published: February 2015

As I write this overview, the price of benchmark Brent crude ranges between U.S. $62 and $65/bbl, and heavy crude oils, such as Midway Sunset (13°API), hover around U.S. $53/bbl. There are many reasons for the increase in oil price, including market forces, political tensions, and speculation that world conventional-oil production is about to peak. Propelled by high oil prices, the phrase "peak oil" has become familiar to most people. I Googled the phrase "peak oil," and it produced 14,200,000 hits. Worries about the finite nature of the oil supply are reported in the common media and resonate with the public paying high prices for gasoline at the pump.

The perception that peak oil is imminent and that the world is running out of hydrocarbon molecules is inconsistent with the reality of the heavy-hydrocarbon (less than 20°API) resource base. Conservative estimates of the volume of heavy hydrocarbons place the total resource in excess of 6 trillion bbl. If world oil demand could be held to 80 million B/D, the ratio of heavy resource to production rate is greater than 200 years. These figures do not include oil-shale resources that, in the U.S. alone, are estimated to be greater than 2 trillion bbl.

In my view, at least two significant issues exist regarding heavy-hydrocarbon exploitation. The first is expansion of the knowledge base of specialized techniques needed to exploit the resource. Steam injection, whether in cyclic, drive, or gravity-drainage modes, has proved successful and economical. Yet, many resources do not fit the profile needed for steam injection. The suite of in-situ recovery technologies for heavy and viscous oil, ranging from waterflooding to in-situ combustion to solvent injection and electrical heating remains to be perfected. The development of such a suite thereby allows transformation of heavy resources to reserves and, ultimately, to a producible product.

The second, and seemingly more difficult, issue is minimization of carbon dioxide (CO2) emissions associated with heavy-oil production operations. At oil/steam ratios ranging from 0.3 to 0.5, production of a barrel of heavy oil produces 80 to 140 lbm of CO2. Similarly, exploiting Alberta tar sands, by mining and upgrading bitumen to 1 bbl of light synthetic crude, produces slightly more than 220 lbm of CO2. For reference, combustion of 1 bbl of oil may emit 800 to 900 lbm of CO2. Thus, the CO2 footprint of heavy-oil production is significant in relation to that of combustion. These sobering figures are offset by the reality that the heat needed for thermal recovery comes increasingly from cogeneration operations that produce electricity and steam with large overall efficiency. This trend toward integrated energy solutions and greater efficiency is an important part of our energy future and holds one of the keys to producing heavy oil while keeping CO2-related emissions in check.

Heavy Oil additional reading available at the SPE eLibrary: www.spe.org

SPE 97279 "North Slope Heavy-Oil Sand-Control Strategy: Detailed Case Study of Sand-Production Predictions and Field Measurements for Alaskan Heavy-Oil Multilateral Field Developments," by R.C. Burton, SPE, ConocoPhillips, et al.

SPE 94001 "Downhole Harmonic-Vibration Oil-Displacement System: A New IOR Tool," by T. Zhu, SPE, U. of Alaska, et al.

SPE 97708 "Controlling Water Risks in Extra-Heavy-Oil Environments," by E. Pereira, SPE, Sincor, et al.

SPE 97894 "Pore-Level Investigation of Heavy-Oil Depressurization," by K. Shahabi-Nejad, Heriot-Watt U., et al.