With the help of a new $580,000 US Department of Energy (DOE) grant, the earth scientists will use their skills at interpreting underground sound to seek out "sweet spots"--pockets of natural gas and oil contained in fractured porous rocks--in a Wyoming oil field. If the method proves effective at determining where to drill wells, it could eventually be used at oil and gas fields across the country.
A major domestic source of natural gas is low-permeability or "tight" gas formations. Oil and gas come from organic materials that have been cooked for eons under the pressure and high heat of the Earth's crust. Some underground reservoirs contain large volumes of oil and gas that flow easily through permeable rocks, but sometimes the fluids are trapped in rocks with small, difficult-to-access pores, forming separate scattered pockets. Until recently, there was no technology available to get at tight gas.
Tight gas is now the largest of three unconventional gas resources, which also include coal beds and shale. Production of unconventional gas in the United States represented around 40 percent of the nation's total gas output in 2004, according to the DOE, but could grow to 50 percent by 2030 if advanced technologies are developed and implemented.
One such advanced technology is the brainchild of Mark E. Willis and Daniel R. Burns, research scientists in the Department of Earth, Atmospheric and Planetary Sciences (EAPS), and M. Nafi Toksoz, professor of EAPS. Their method involves combining data from two established, yet previously unrelated, means of seeking out hidden oil and gas reserves.
To free up the hydrocarbons scattered in small pockets from one to three miles below ground, oil companies use a process called hydraulic fracturing, or hydrofrac, which forces water into the bedrock through deep wells to create fractures and increase the size and extent of existing fractures. The fractures open up avenues for the oil and gas to flow to wells.
To monitor the effectiveness of fracturing and to detect natural fractures that may be sweet spots of natural gas, engineers gather acoustic data from the surface and from deep within wells. "Surface seismic methods are like medical ultrasound. They give us images of the subsurface geology," Burns said. Three-dimensional seismic surveys involve creating vibrations on the surface and monitoring the resulting underground echoes. "When the echoes change, fractures are there," Willis said.
A method called time-lapse vertical seismic profiling (VSP) tends to be more accurate because it collects acoustic data directly underground through bore holes. "Putting the receivers down into a well is like making images with sensors inside the body in the medical world," Burns said. "The result is the ability to see finer details and avoid all the clutter that comes from sending sound waves through the skin and muscle tissue to get at the thing we are most interested in seeing."
Time-lapse VSP is expensive and not routinely used in oil and gas exploration. The EAPS research team, working with time-lapse VSP data collected by industry partner EnCana Corp., came up with unique ways to look at the data together with microseismic data from the tiny earthquakes that are produced when the rock is fractured. "If we record and locate these events just as the US Geological Survey does with large earthquakes around the world, we get an idea of where the hydrofrac is located. Then we look at the time-lapse VSP data at those spots and try to get a more detailed image of the fracture," Burns said.
The MIT team hopes to show that this new approach is the most effective way to find sweet spots. "If we can demonstrate the value of time-lapse VSP, this tool could be used in a wider fashion across the United States on many fields," Willis said.
Elizabeth A. Thomson | MIT News Office
Linear potentiometer LRW2/3 - Maximum precision with many measuring points
17.05.2017 | WayCon Positionsmesstechnik GmbH
First flat lens for immersion microscope provides alternative to centuries-old technique
17.05.2017 | Harvard John A. Paulson School of Engineering and Applied Sciences
Staphylococcus aureus is a feared pathogen (MRSA, multi-resistant S. aureus) due to frequent resistances against many antibiotics, especially in hospital infections. Researchers at the Paul-Ehrlich-Institut have identified immunological processes that prevent a successful immune response directed against the pathogenic agent. The delivery of bacterial proteins with RNA adjuvant or messenger RNA (mRNA) into immune cells allows the re-direction of the immune response towards an active defense against S. aureus. This could be of significant importance for the development of an effective vaccine. PLOS Pathogens has published these research results online on 25 May 2017.
Staphylococcus aureus (S. aureus) is a bacterium that colonizes by far more than half of the skin and the mucosa of adults, usually without causing infections....
Physicists from the University of Würzburg are capable of generating identical looking single light particles at the push of a button. Two new studies now demonstrate the potential this method holds.
The quantum computer has fuelled the imagination of scientists for decades: It is based on fundamentally different phenomena than a conventional computer....
An international team of physicists has monitored the scattering behaviour of electrons in a non-conducting material in real-time. Their insights could be beneficial for radiotherapy.
We can refer to electrons in non-conducting materials as ‘sluggish’. Typically, they remain fixed in a location, deep inside an atomic composite. It is hence...
Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.
Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...
An Australian-Chinese research team has created the world's thinnest hologram, paving the way towards the integration of 3D holography into everyday...
24.05.2017 | Event News
23.05.2017 | Event News
22.05.2017 | Event News
26.05.2017 | Life Sciences
26.05.2017 | Life Sciences
26.05.2017 | Physics and Astronomy