What's new in production

	Vol. 228 No. 8
VICTOR SCHMIDT, DRILLING ENGINEERING EDITOR, schmidtv@worldoil.com

Biosurfactants. There is a holy grail for the oil industry; but it isn’t made of gold. It is a living thing, a microbe, or several different microbes, that can work their magic downhole in the reservoir to free the 60-70% of oil and gas remaining in fields after primary and secondary recovery.

Researchers across the globe are seeking these elusive “bugs” from the depths of the mid-ocean ridges, where extremophiles live, to more common surface and soil-dwelling bacteria that produce biofilms, which act as surface active agents-basically oilfield soaps. The goal is to locate bacteria that can alter the oil/bitumen in place within the reservoir environment.

If the hydrocarbon can be transformed into methane, then it can be extracted as a gas with normal technologies. Alternatively, if the hydrocarbon’s viscosity can be lowered, so that the oil will flow, then extraction is possible using conventional techniques. These goals require a lot from the microbes; they must be anaerobic (non-oxygen dependent), tolerant of high salinity and capable of surviving in a high-temperature environment.

Conversion to methane requires a microbe that metabolizes petroleum and expresses methane as a waste. Many of these creatures are part of the Archaea family and live in the most extreme environments: high salinity (Dead Sea, Great Salt Lake), high acid (mine tailings) or high temperatures (volcanic vents, geothermal springs).

These bacteria may also produce oil along with the methane, since they produce enzymes that can break long-chain hydrocarbons into shorter, more useable chains. Most importantly, these shorter-chain forms will flow, while their precursors remain bound in the rock matrix.

Surfactant-producing bacteria are more accessible, but are more fragile for oilfield work. They are useful for more shallow reservoirs where the oil is “caught” in the permeability trap of the rock’s pore space. By introducing a surfactant that can lower the surface tension between rock grains and oil droplets or oil and bound water, more oil will flow from poorly producing or abandoned wells and fields.

According to the US Department of Energy’s (DOE) National Energy Technology Laboratory (NETL), more than 300 billion bbl remain in US reservoirs after conventional Enhanced Oil Recovery (EOR) techniques have reached their economic limit. The US DOE Reservoir Database has over 600 reservoirs that meet the criteria for bacterial EOR. After using standard technologies, these reservoirs hold up to 12 billion bbl of unrecoverable oil, which could be extracted, if suitable bacteria were available.

To help the industry locate and develop bacteria for this purpose, NETL funded a three-year project that began in October 2004. The study’s purpose is to move biosurfactant-effective oil recovery from laboratory investigations to field applications. The University of Oklahoma and Arrow Holding Inc. are performing the study.

Thus far, researchers have identified effective biosurfactant-producing bacteria, located seven oil formations with lower salinities (in which to test their effectiveness), developed a nutrient mix and field tested the bacteria-with success. The bacteria are effective in reservoirs with salinities up to 11%.

According to Professor Michael McIneney of the University of Oklahoma, a principal researcher on the project, two wells were treated with a mix of two strains of bacillis bacteria, both of which produce an effective lipopeptide surfactant for oil production. The three-month well tests were spot treatments: The bacteria were mixed with a glucose and nutrient blend in a brine solution, and then spotted to the bottom of the wells. The wells, which had been producing 2.5 bopd, began to yield 6-12 bopd, a substantial improvement. Over the course of the test, McIneney says that 330 bbl of additional oil were gathered, over what the wells would normally produce.

According to NETL, if using bacteria to generate biosurfactants is effective in reducing residual oil saturation by only 10%, then some 300 million bbl would be added to US reserves. The study will be complete at the end of September and the final report has been submitted. It should be approved for release by the end of August. Considering the number of abandoned oil fields across the globe, this bio-EOR could release many millions of bbl for future use.

Oil shale. China reported the discovery of an oil shale deposit with reserves estimated at 1 billion tonnes (7-9 billion bbl oil). The Liaoning Geological Bureau made the discovery in northeastern China near Chaoying in the Jiufotang area, Liaoning province. In 2005, Royal Dutch Shell created a joint venture to explore and develop oil shale deposits in Jilin province, next to Liaoning province.

New output. In the Exmouth Basin offshore western Australia, Apache Corp. flowed 9,694 bopd from its Theo 3-H well, the first Van Gogh field horizontal well. The well was drilled to a 10,598-ft TD into the Top Barrow with a 4,554-ft lateral in the formation’s top. The company is operator with 52.5% percent and will drill up to 18 laterals this year. First production is scheduled for 2009.

In Yemen, DNO is producing 2,548 bopd from the Godah No. 6 well out of the Qishn S1-A sand. The well is in Block 32 and was drilled to a 5,748-ft TD.

Dolphin Energy Ltd. began producing natural gas from its wells in Qatar’s North field. Up to 2 Bcfd will be transported to Abu Dhabi by a 48-in., 364-km subsea pipeline to the company’s gas processing plant in Ras Laffan. The pipeline wil be able to handle up to 3.2 Bcfgd. Dolphin has a development and production sharing agreement with Qatar to produce the gas for up to 25 yr.

The Minke Main field began producing gas in the southern North Sea. GDF Britain Ltd. is operator of the Block 44/24a field, which is ramping up to produce 60 MMcfd of natural gas. The field has a single well in 147 ft of water, tied back by a 9-mi subsea pipeline to the D15 platform offshore Holland. There it will enter the NGT Pipeline System and be sent to Uithuizen, the Netherlands.

Shell began producing from Deimos in the Gulf of Mexico. This Mars basin project is being developed in two phases. This first phase ties back three wells to the Mars TLP. The field has 535 ft of net pay in established and new pay zones, which will be produced at 30,000 boepd. It is in 3,000 feet of water and straddles Mississippi Canyon Blocks 762 and 806. Shell is operator with 71.5% in partnership with BP (28.5%).