What's new in production

	Vol. 227 No. 10
VICTOR SCHMIDT, DRILLING ENGINEERING EDITOR

Beyond SAGD. Canada’s heavy oil sands are producing and encouraging the industry to experiment with new ways to get more oil. Steam Assisted Gravity Drainage (SAGD) is the common production technology applied, but others are under development or in use.

However, there are some problems. SAGD uses lots of water and natural gas to generate steam. This is spurring research into new production forms that use fewer resources. While this editor has no direct experience with any of these efforts, he submits them to the reader for their consideration.

The Petroleum Technology Research Centre in Regina, Saskatchewan, Canada, is conducting research via Joint Implementation of Vapour Extraction (JIVE). This program is a collaborative effort between PTRC, Alberta Research Council, Saskatchewan Research Council, Nexen, Husky Energy, Canadian Natural Resources Ltd. and other heavy oil producers. The project is testing the effectiveness of a proprietary vapor extraction process, Vapex. 

The process uses an injection mix of gases: methane, CO₂, propane and butane, depending on the reservoir and its rock character. SAGD uses water as a heat carrier to temporarily alter oil viscosity. Using the Vapex process, the gases dissolve into the thick oil, chemically reducing oil viscosity to improve flow. Lighter gravity oil flows down to horizontal wells, where it is collected, Fig 1. The carrier, solvent and produced casing gases are then recycled, so the process is efficient and relatively non-polluting.

Fig. 1. The proprietary Vapex process uses an injection gas to carry a solvent gas, which reduces oil viscosity. Source: Petroleum Technology Research Centre.

The process avoids two major SAGD issues: (1) 4 bbl of fresh water used for every 10 bbl of oil produced and (2) about 83.7 tons of CO₂ released for each 1,000 bbl of oil recovered.

Because the process uses gases in their natural state without adding heat or water, the project hopes to reduce emissions and water usage by 90%, compared to standard SAGD processes. JIVE participants hope to raise heavy oil recovery factors to 30% to 50% of oil in place, from 5% to 15% at present. The improved recovery factor could generate up to 10 billion bbl of additional oil, according to PTRC.

Another heavy oil technology being put to use in Canada is Pressure Pulse Technology (PPT) from Wavefront Energy and Environmental. The company recently entered a project jointly with Greentree Gas & Oil to install PPT in eight injection wells in the Rodney South field. Two horizontal wells will drain the oil produced by the process.

This technology operates by pulsing the injection water with a low-amplitude pressure wave. According to Wavefront’s literature, “the injected liquid dilates the pore space through an elastic response” helping heavy oil move more readily through the rock. Greentree used the technology successfully in an earlier project.

In a related development, PPT has been licensed to Halliburton’s Energy Services Group from Wavefront for joint research, development and implementation. Halliburton has a nonexclusive license in the US and Canada and an exclusive license for all the rest of the world.

CO₂ flood. On a lighter-oil note, carbon dioxide flooding is beginning to take on wider application. Use of CO₂ for enhanced oil recovery has been limited to areas where the gas was readily available, predominantly West Texas. Now, other sources of the gas are being considered.

The Energy Policy Act of 2005 authorized the US Department of Energy to find and fund demonstration projects to promote the capture, transportation and injection of produced CO₂ for sequestration into oil and gas fields, while boosting oil and natural gas production. Using this authority, DOE will fund a CO₂ project proposed by the University of Alabama – Birmingham (UAB).

UAB, Southern Co., Denbury Resources Inc. (operator), University of Alabama, Alabama A&M University, Geological Survey of Alabama and the University of North Carolina are partnering with DOE on the project. It will cost close to $6 million, with DOE funding about $3 million and the partners splitting the remainder.

The project will inject CO₂ from an electric utility, Southern Co., into Citronelle field, in Mobile County, Alabama, to improve oil production and assess the CO₂-storing potential of the reservoir. The project will also provide input to improve computer simulations of oil, water, and CO₂ migration for scientists, utility planners, and climate-change modelers to use. Using CO₂ injection, new production could add up to 64 million bbl of oil to Citronelle’s ultimate recovery.

Diamond films. Manufacturers have used diamond film technology for many years to produce industrial cutting tools. This technology is now coming to the oil field for seals and other high pressure wear surfaces.

John Crane Inc. has been working with Advanced Diamond Technologies, Inc. for several years to develop and commercialize diamond films to improve friction and wear on mechanical seal faces. Together the companies have produced a diamond film-enhanced, dual-segmented carbon ring seal, which is designed to prevent the migration of bearing oil to the dry gas seal cartridge on turbo-compressor equipment. According to John Crane, typical barrier seals are exposed to seal supply pressures around 3 – 5 psi, but where secondary vent lines are going to flare, pressure requirements have increased, creating the need for a more durable seal. Watch for more diamond seal applications in the near future.