Mass Spectrometry

Scary Words; but,

Easy Technology to Give the Client Better Information

The scope of this article has changed since its initial inception (in other words, there is

still a learning curve for all of us regarding this technology). I was going to focus on the

equipment, its setup and maintenance. Baker is testing new and better equipment as we

speak so that would be fairly pointless.

These are the fundamentals of the equipment technology (no, don’t be afraid): mass

spectrometry (yes, you can use mass spec or MS if you like) instruments consist of three

modules:

• An ion source (our gas trap starts this), which can convert gas phase sample

molecules into ions

• A mass analyzer, which sorts the ions by their masses by applying electromagnetic

fields

• A detector, which measures the value of an indicator quantity and thus provides

data for calculating the abundances of each ion present.

The technique has both qualitative and quantitative uses. These include:

• Identifying unknown compounds (rock, paper, scissors)

• Determining the isotopic composition of elements in a molecule (water – H2O vs.

heavy water – H3O)

• Determining the structure of a compound by observing its fragmentation (very

important for breaking down C1-C10 or more).

Other uses include quantifying the amount of a compound in a sample (gas ratios for

us).

Mass spec is now in very common use in analytical laboratories that study physical,

chemical, or biological properties of a great variety of compounds. We should not be

afraid to use it … if it is ok for CSI television shows, its ok for us.

With mass spectrometers in our industry, we can with training, do the following and

more in the field … real time:

• Safety: no flammable sources in the unit

• Perform an almost instantaneous sample analysis instead of an analysis with a

2-3min cycle

• Perform petroleum migration pathway mapping

• Identify characterization of seals to oil and gas

• Identify dry holes proximal to undiscovered hydrocarbons

• Delineate pay or bypassed pay within penetrated sections

• Identify fluid pressure compartments

• Characterize petroleum-water transition zones

• Delineate reservoir compartmentalization

• Have less equipment (no H2 generator required) and maintenance and

therefore perform a more cost effective analysis for the clients

• Heck, we can even tell bit wear before the driller knows it

What is mass spectrometry?

This goes back to the dreaded Chemistry 101 and Physics 101 so bear with me …

Everything is composed of one or a combination of elements that we all saw on the

periodic table of elements.

Each of these elements (or their combinations) has a very specific atomic number which

is different than the atomic mass.

Review:

1. An element's or isotope's atomic number tells how many protons are in

its atoms.

2. An element's or isotope's mass number tells how many protons and

neutrons are in its atoms

Hydrogen, which is inorganic and the most basic element, has an atomic number of 1 and

a mass number of 1.0094. We are used to dealing with C1 – C5. Carbon (an organic

element) has an atomic number of 6 and a normalized mass number of 12.011 (isotopes,

or variations, account for carbon 14 and so forth). So, where does the carbon 1-5 we deal

with come from and how can mass spectrometry be a benefit?

The C1-C5 is only a designation of how many carbon atoms are attached together in

molecules, the structure. These molecules can be detected by our gas chromatograph.

Please note, the GC is limited to detecting C1-C5 within our constraints.

Mass spec is a benefit because it can detect beyond what we call the heavies IC4, NC4,

IC5 and NC5. It can detect C10 and more. Talk about gas ratio specification!

Mass Spec can also detect inorganic molecules. You can actually put a banana by the

intake of a mass spec (HUGE DISCLAMER HERE - in laboratory experiments only)

and it will tell you what is in the banana if programmed to do so.

Why is it important that a mass spec can detect inorganic molecules if all we are looking

for is carbon/organic molecules?

With mass spec, we can locate and find our valuable, resources more safely and cost

effectively.

Detection is the key. If we are not on as much of a wild goose chase then time and

therefore safety is saved.

You have had the chemistry review, now the physics.

Just a reminder … In chemistry and physics, the atomic number (also known as the

proton number) is the number of protons found in the nucleus of an atom and therefore

identical to the charge number of the nucleus.

There is a ratio known as the mass to charge ratio. The importance of the mass to charge

ratio, according to classical electrodynamics, is that two particles with the same mass to

charge ratio move in the same path in a vacuum when subjected to the same electric and

magnetic fields.

How the physics works:

The basic principle

If something is moving and you subject it to a sideways

force, instead of moving in a straight line, it will move in a

curve - deflected out of its original path by the sideways

force.

Suppose you had a cannonball travelling past you and you

wanted to deflect it as it went by you. However, all you've

got is a jet of water from a hose that you can squirt at it. The

hose is not going to make a lot of difference because the

cannonball is so heavy. It will hardly be deflected at all

from its original course.

If you then tried to deflect a table tennis ball travelling at the

same speed as the cannonball using the same jet of water;

because this ball is so light, you will get a huge deflection.

The amount of deflection you will get for a given sideways

force depends on the mass of the ball. If you knew the speed

of the ball and the size of the force, you could calculate the

mass of the ball (in other words the element) if you knew

what sort of curved path it was deflected through. The less

the deflection, the heavier the ball.

Note: I'm not suggesting that you

personally would have to do the

calculation, although the math isn't

actually very difficult - certainly no

more than Baker Hughes’s standard

for a simple field specialist!

You can apply exactly the same principle to atomic sized

particles.

An outline of what happens in a mass spectrometer

Atoms can be deflected by magnetic fields (the water hose) -

provided the atom is first turned into an ion (a charged

particle formed by changing the number of electrons).

Electrically charged particles are affected by a magnetic

field although electrically neutral ones aren't.

The sequence is:

Stage 1: Ionization

The atom is ionized by knocking one or more electrons off to give a positive ion. This is

true even for things which you would normally expect to form negative ions (chlorine,

for example) or never form ions at all (argon, for example). Mass spectrometers always

work with positive ions.

Stage 2: Acceleration

The ions are accelerated so they all have the same kinetic energy.

Stage 3: Deflection

The ions are then deflected by a magnetic field (after passing through a really, really

small hole in a separating plate) according to their masses. The lighter they are, the more

they are deflected.

The amount of deflection also depends on the number of positive charges on the ion - in

other words, on how many electrons were knocked off in the first stage. The more the ion

is charged, the more it gets deflected.

Stage 4: Detection

The beam of ions passing through the machine is detected electrically.

This is recorded as the mass spectrum of what is passing through the mass spec.

The important thing is that you can detect any element this way. All organics have

inorganics near them which can be indicators of the classic W’s of writing: who, what,

when, where and even why (geologically speaking) of what we get paid to help find.

The more difficult our resources become to find and capture, the more we should utilize

the technology available to do so more effectively and therefore safely.

Please note:

• Mass specs still need a clean, dry source sample; so, the filters, condensate bottles

and pneumatics panel are still essential.

• They can be calibrated with your breath based on the normal levels of CO2

produced by humans, though this is only done in dire, strange circumstances.

• They also have one very weak point mechanically, the turbo pump required to

form the vacuum necessary spins at upwards of 140,000rpm (no bumping

allowed).

As alluded to earlier; the cool stuff comes from the detection of inorganics in addition to

our normal organic collection, ease of use and safety.

The real question is what will the dang thing do for me as far as the client is

concerned?

It comes down to cost vs. benefit. We can do more with less

• The number one benefit is safety

There is no flame involved in the sample analysis. The units do not create a

possible ignition source for the sample being tested. This could possibly be an

insurance benefit to Baker Hughes since the only ignition source in a purged unit

with an intrinsically safe system would now be exterior to the unit. No gas bottles

are required in the unit to support the mass spec which further diminishes the

safety hazard.

• Perform an almost instantaneous sample analysis instead of an analysis with a

2-3min cycle

A GC is dependent on process time. It is designed to separate carbon molecules

based on their size by the amount of time it takes them to travel through a series of

coiled microtubules. The longer the transition time, the heavier the molecule

(molecular shape is also a factor). A mass spec is not dependent on transition

times. The importance is that a mass spec can help delineate sample components

from thinly bedded formations as soon as they pass the detector (~2-3 seconds

from start to finish). The quicker the detection is, the more accurate the depth

correlation is.

• Perform petroleum migration pathway mapping

By determining proximity to a seal based on hydrogen “leakage” from

hydrocarbon and or water components, a seal and therefore the pathway associated

with it can be mapped. The closer you are, the more leakage is detected and vice

versa. No seal is 100% impermeable (ask Dr, Ruth). If data is collected from the

inorganics, percentages of organics can be indicative of proximity and therefore

organic path relative to the collection points (assuming relative formation

conformity). In high transition zones (such as coming out of a salt dome), this may

be difficult to determine.

• Identify characterization of seals to oil and gas

The better the seal, the less hydrocarbon bleed through there is. Better seals come

from lithologically sound formations of compacted shale, salt, faults, etc.

Conversely, if there is a weak seal, the greater the bleed through and the earlier a

detection of hydrocarbons can be made. The same is true for water bearing sands

as there is an increase in detectible hydrogen.

• Identify dry holes proximal to undiscovered hydrocarbons

Dry holes present increased levels of hydrogen from water and or water itself,

when looked at in comparison to possible bleed through levels, this can indicate

proximity. Directional wells can be steered toward or away from a certain

zone utilizing this information.

• Delineate pay or bypassed pay within penetrated sections

When used with other common indicators such as gamma and resistivity, mass

spec can be a poor man’s determination of the contact zones by utilizing advanced

wetness and balance ratios along with Pixler ratios. These ratios in common use

use only C1-C5. Expanding the common ratios to the scope of the carbons being

collected, the specific location of gas-oil and gas-water contacts can be more

accurately determined.

Figure 1 is only half of a mass spec log. Figure 2 contains the inorganic

components.

Note the wetness/balance crossovers and corresponding Pixler ratios in Figure 1

and the large increase in the corresponding absolute inorganics.

Figure 1

Wetness/Balance

Pixler

By looking for wetness/balance crossovers as well as Pixler ratios, boundaries can

easily be established. Confirmation can be made with correlation of inorganics.

Figure 2 Inorganics

Absolute Inorganics ………………………………………….

• Identify fluid pressure compartments

Pore pressures above and below hydrostatic, occur in lower Silurian, Clinton

Medina and Tuscarora sandstone reservoirs in the Appalachian basins as well as in

all other regions from published analysis. From the standpoint of utilizing mass

spec as an indicator, the Pixler ratios and wetness/balance ratios can be indicative

of specific compartmentalization through appreciable changes in their

comparisons. Typical pore pressure analysis takes into account parameters

associated with “filtered data”. Mass spec can assist in the confirmation of this

data with real time associations.

• Characterize petroleum-water transition zones

The mass spec can detect water content definitively since it can detect inorganics

and therefore is an indicator of this transition zone with no ambiguity –either it is

water or it is not.

• Delineate reservoir compartmentalization

See above for indicators.

• Have less equipment (no H2 generator required) and maintenance and

therefore perform a more cost effective analysis for the clients

An extension of this was alluded to with the mention that the only calibration

required is with human breath which contains a specific CO2 level. This will

reduce costs as there is not the need for multiple calibration gas bottle purchases,

transportation of the bottles to drilling sites, connection equipment for the bottles,

safety issues associated with flammable gasses, and manpower/time associated

with repeated calibration.

• Heck, we can even tell bit wear before the driller knows it

When a bit wears, the iron in the bit releases hydrogen and helium. Hydrogen

anomalies can accompany bit wear. Helium is an element rarely found in nature

worldwide and is then found only in specific quantities and in concentration in

only a few places (that is why the Hindenburg blew up – the Germans had to use

hydrogen because America would not let them have the helium). When an

increase in helium concentration is seen while drilling, it is an indication of bit

wear. A sharp increase indicates bit burn and the bit being worn out. Helium is

not a natural product of hydrocarbon drilling.

Baker Hughes INTEQ does not guarantee the accuracy or correctness of

interpretations provided in or from this information. Since all

interpretations are opinions based on measurements, Baker Hughes INTEQ

shall under no circumstances be held responsible for consequential

damages or any other loss, costs, damages or expenses incurred or

sustained in connection with the use of any such interpretations.

Baker Hughes INTEQ disclaims all expressed and implied warranties

related to its service which is governed by Baker Hughes INTEQ's

standard terms and conditions.