Applications

Mass spectrometry for mud logging

GAOS MS-20-7. TOF-MS for mud logging

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Mud logging


Mud logging – method of qualitative and semi-quantitative gas analysis in mud during drilling or from selected samples. 

This method gives direct information about parameters of oil and gas reservoirs and other geological objects in well.


Modern technologies of well construction, including high-speed drilling ( > 50 m/hour), horizontal drilling, geological investigation in drilling require more data from mud gas analysis:

  • number of components
  • concentration range
  • speed of analysis   
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Different geology – different gas composition


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Gas scheme


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Gas Chromatography


The most widely used technique is Gas Chromatography. This instrument separates components from a mixture by selectively adsorbing and desorbing each compound at different rates. Components start to separate, depending on their affinity for the active surface of the packing or the column tubing. At the end of the column, components elute, each with unique retention time, and pass into a detector. The different detectors used to analyze the compounds eluting from the GC column include the FID, the TCD, the catalytic combustion detector (CCD), the MS detector, and the infrared (IR) absorption spectrometer.


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Advantages

Disadvantages

  • Accuracy
  • Reliability
  • Sensitivity
  • Speed of analysis (2 minutes)
  • No isotope analysis (if not GC-MS)

Mass Spectrometry


Mass spectrometry (MS) is an analytical technique that measures the mass-to-charge ratio of ions. The results are typically presented as a mass spectrum, a plot of intensity as a function of the mass-to-charge ratio. Mass spectrometry is used in many different fields and is applied to pure samples as well as complex mixtures. 

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A mass spectrum is a plot of the ion signal as a function of the mass-to-charge ratio. These spectra are used to determine the elemental or isotopic signature of a sample, the masses of particles and of molecules, and to elucidate the chemical identity or structure of molecules and other chemical compounds.

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Quadrupole Mass Spectrometry


Quadrupole mass analyzers use oscillating electrical fields to selectively stabilize or destabilize the paths of ions passing through a radio frequency (RF) quadrupole field created between 4 parallel rods. Only the ions in a certain range of mass/charge ratio are passed through the system at any time, but changes to the potentials on the rods allow a wide range of m/z values to be swept rapidly, either continuously or in a succession of discrete hops.

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Advantages

Disadvantages

  • High sensitivity
  • Worse precision at low mass 
  • Low limit of upper registered masses
  • Sensitivity to mechanical impact and electrode deterioration
  • Sequential analysis


Time-of-Flight Mass Spectrometry


In time-of-flight (TOF) analyzer one measures the time of drift in field-free volume.

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Advantages

Disadvantages

  • Resolution
  • High limit of upper registered masses
  • Low sensitivity to accident mechanical impact and internal surface  deterioration
  • Simple algorithm of peak identification
  • Parallel measurement (analysis time of all components– about 1 s)

  • Worse sensitivity (to QMS)


GAOS MS-20-7. TOF-MS for mud logging



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Analytical unit

Electronic unit



Analytical parameters


Parameters Value
Range of masses, Da 1-200
Resolution, M/ΔM 200
Registration channels
-Analogue
-Counter
16
16
Analyzed components CH4, C2H6, C3H8, i-C4H10, C4H10, C5H12, C6H14, H2, He, N2, Ar, O2, CO2, H2S, SO2
Analysis time, no more than, s 2
Dynamic range, % vol. 10-4-100%
Calibration Automatic
Baseline correction Automatic


Design


  • Modular configuration
  • Easy to mount/dismount
  • Transportability
  • Stability and reliability in field without CRM
  • Convenient service and control
  • High automatization with necessary locking
  • Maintenance period 8-15 months
  • The long period of exploitation

Control software

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Results


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Analytical task


Components Concentration range, % vol.
CH4 5,0 * 10-4 10,0
C2H6 5,0 * 10-4 1,0
C3H8 5,0 * 10-4 1,0
C4H10 5,0 * 10-4 1,0
C5H12 2,0 * 10-4 0,1
C6H14 2,0 * 10-4 0,1
N2 0,1 80,0
Ar 1,0 * 10-2 2,0
He 1,5 * 10-3 1,0
O2 0,1 25,0
CO2 0,1 1,0
SO2 0,1 1,0
H2S 1,0*10-2 2,0

Results


Components

Concentration, % vol.

Difference, % vol.

SD,

% vol.

CRM

Measurement

СН4

10,31 ± 0,01

10,297

0,013

0,042

С2Н6

1,99 ± 0,09

2,075

0,085

0,004

С3Н8

0,99 ± 0,03

1,024

0,034

0,0012

С4Н10

0,533 ± 0,050

0,583

0,050

0,0002

i- С4Н10

0,054 ± 0,006

0,048

0,006

0,0005

С5Н12

0,0098 ± 0,0006

0,00989

0,00009

0,00004

С6Н14

0,000117 ± 0,00007

0,00118

0,00001

0,00001

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