Understanding how oil and gas molecules, water and rocks interact at the nanoscale will help make extraction of hydrocarbons through hydraulic fracturing more efficient, according to Rice University researchers.
Rice engineers George Hirasaki and Walter Chapman are leading an effort to better characterise the contents of organic shale by combining standard nuclear magnetic resonance (NMR) – the same technology used by hospitals to see inside human bodies – with molecular dynamics simulations.
The work presented this month in the Journal of Magnetic Resonance details their method to analyse shale samples and validate simulations that may help producers determine how much oil and/or gas exist in a formation and how difficult they may be to extract.
Oil and gas drillers use NMR to characterise rock they believe contains hydrocarbons. “NMR instruments are among several tools in the string sent downhole to “log,” or gather information, about a well,” said Hirasaki.
In conventional reservoirs, he said, the NMR log can distinguish gas, oil and water and quantify the amounts of each contained in the pores of the rock from their relaxation times -known as T1 and T2-as well as the diffusivity of the fluids. “If the rock is water-wet, then oil will relax at rates close to that of bulk oil, while water will have a surface-relaxation time that is a function of the pore size,” Hirasaki said.
Understanding how oil and gas molecules, water and rocks interact at the nanoscale will help make extraction of hydrocarbons through hydraulic fracturing more efficient, according to Rice University researchers.
Rice engineers George Hirasaki and Walter Chapman are leading an effort to better characterise the contents of organic shale by combining standard nuclear magnetic resonance (NMR) – the same technology used by hospitals to see inside human bodies – with molecular dynamics simulations.
The work presented this month in the Journal of Magnetic Resonance details their method to analyse shale samples and validate simulations that may help producers determine how much oil and/or gas exist in a formation and how difficult they may be to extract.
Oil and gas drillers use NMR to characterise rock they believe contains hydrocarbons. “NMR instruments are among several tools in the string sent downhole to “log,” or gather information, about a well,” said Hirasaki.
In conventional reservoirs, he said, the NMR log can distinguish gas, oil and water and quantify the amounts of each contained in the pores of the rock from their relaxation times -known as T1 and T2-as well as the diffusivity of the fluids. “If the rock is water-wet, then oil will relax at rates close to that of bulk oil, while water will have a surface-relaxation time that is a function of the pore size,” Hirasaki said.
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