physics

Surface nuclear magnetic resonance

Surface nuclear magnetic resonance is a physics topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Surface nuclear magnetic resonance rather than just read about it. In short: Surface nuclear magnetic resonance (SNMR), also known as magnetic resonance Sounding (MRS), is a geophysical technique specially designed for hydrogeology. It is based on the principle of nuclear magnetic resonance (NMR) and measurements can be used to indirectly estimate the water content of saturated and unsaturated zones in the earth's subsurface.

Key takeaways

Surface nuclear magnetic resonance belongs to physics; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Surface nuclear magnetic resonance to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Surface nuclear magnetic resonance from memory before moving on to harder problems.

Reference excerpt

Surface nuclear magnetic resonance (SNMR), also known as magnetic resonance Sounding (MRS), is a geophysical technique specially designed for hydrogeology. It is based on the principle of nuclear magnetic resonance (NMR) and measurements can be used to indirectly estimate the water content of saturated and unsaturated zones in the earth's subsurface. SNMR is used to estimate aquifer properties, including the quantity of water contained in the aquifer, porosity, and hydraulic conductivity.

History The MRS technique was originally conceived in the 1960s by Russell H. Varian, one of the inventors of the proton magnetometer. SNMR is a product of a joint effort by many scientists and engineers who started developing this method in the USSR under the guidance of A.G. Semenov and continued this work all over the world. Semenov's team used nuclear magnetic resonance (NMR) for non-invasive detection of proton-containing liquids (hydrocarbons or water) in the subsurface. The Voevodsky Institute of Chemical Kinetics and Combustion of the Siberian Branch of the Russian Academy of Sciences fabricated the first version of the instrument for measurements of magnetic resonance signals from subsurface water ("hydroscope") in 1981.

Principles The basic principle of operation of magnetic resonance sounding, hitherto known as surface proton magnetic resonance (PMR), is similar to that of the proton magnetometer. They both assume records of the magnetic resonance signal from a proton-containing liquid (for example, water or hydrocarbons). However, in the proton magnetometer, a special sample of liquid is placed into the receiving coil and only the signal frequency is a matter of interest. In MRS, a wire loop 100 m in diameter is used as a transmitting/receiving antenna to probe water in the subsurface. Thus, the main advantage of the MRS method, compared with other geophysical methods, is that the surface measurement of the PMR signal from water molecules ensures that this method only responds to the subsurface water. A typical MRS survey is conducted in three stages. First, the ambient electromagnetic (EM) noise is measured. Then, a pulse of electrical current is transmitted through a cable on the surface of the ground, applying an external EM field to the subsurface. Finally, the external EM field is terminated, and the magnetic resonance signal is measured. Three parameters of the measured MRS signal are:

Amplitude (E0), which depends on the number of protons and hence on the quantity of water. Decay time (T*2), which generally correlates with the mean size of the pores in water-saturated rocks. This is important for aquifer characterization. Phase (j0), which is measured in the field and is used for a qualitative estimation of the electrical conductivity of rocks. As with many other geophysical methods, MRS is site-dependent. Modeling results show that MRS performance depends on the magnitude of the natural geomagnetic field, the electrical conductivity of rocks, the electromagnetic noise and other factors

Usage SNMR can be used in both oil and water exploration, but since oil is generally deep down, the more common usage is in water exploration. With depth resolution of 200 meter, SNMR is the best way to model aquifers.

See also Aquifer storage and recovery Aquifer properties Groundwater model Groundwater pollution Hydraulic tomography Nuclear magnetic resonance Earth's field NMR

References

Worked examples

Example 1 — a first encounter with Surface nuclear magnetic resonance

Start with the simplest possible case. Write down what Surface nuclear magnetic resonance claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In physics, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Surface nuclear magnetic resonance before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Surface nuclear magnetic resonance ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Surface nuclear magnetic resonance

In research: Surface nuclear magnetic resonance appears in physics research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Surface nuclear magnetic resonance in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Surface nuclear magnetic resonance is common in secondary-school and first-year university syllabi. It links to neighbouring topics Hydrology, Nuclear magnetic resonance, so understanding it makes those chapters shorter.
In everyday life: Look for Surface nuclear magnetic resonance outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

Ask Teacher Smith questions about this articleOpens your AI tutor with a question about “Surface nuclear magnetic resonance” →

Affiliate

Preply — study more efficiently by working with a personal tutor. 50% off.

How to study Surface nuclear magnetic resonance in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Surface nuclear magnetic resonance means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Surface nuclear magnetic resonance out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Surface nuclear magnetic resonance in simple terms?

Why does Surface nuclear magnetic resonance matter?

Because it connects several physics ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Surface nuclear magnetic resonance?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Surface nuclear magnetic resonance.