US 4,492,862 A · Method and apparatus for analyzing components of hydrocarbon gases recovered from oil, natural gas and coal drilling operations

Abstract

Beams (11) and (13) produced by helium-neon gas lasers (10) and (12) are directed at photoacoustic absorption cells (20) and (21) containing a flowing sample gas stream recovered from coal, oil and natural gas well drilling. The common hydrocarbon gases and vapors within cell (20) highly absorb the infrared energy emitted by laser (10) thereby producing an acoustic disturbance which is detected by a transducer (34) which produces an electrical output signal proportional to the concentration of the hydrocarbon gases and vapors. The methane gas within cell (21) weakly absorbs the infrared energy of laser beam (13), and thus the resulting output signal produced by a transducer (35) serves as a reference signal for determining the methane concentration. The output signals from transducers (34) and (35) are used by data processing unit (40) to compute the total concentration of hydrocarbon gases and vapors and the concentration of methane gas within cells (20) and (21). A turnable carbon dioxide gas laser (44) produces laser beams (45) and (47) both in the infrared region which are highly absorbed by the propane and n-butane component gases, respectively, flowing through photoacoustic cell (48). The level of energy absorbed from these two beams, as determined by the energy of the acoustic disturbance produced within cell (48) induces production of an electrical output signal by transducer (56) at levels proportional to the concentrations of the propane and n-butane gases in cell (48). The output signals from transducer (56) are then used by data processing unit (40) to compute the concentrations of propane, n-butane gases and C.sub.5.sup.+ gases in the sample.

Claims88

Dependent claims

A method of determining the composition of hydrocarbon gases extracted during drilling operations, comprising the steps of:

(a) directing a first laser beam at a frequency strongly absorbed by methane gas and other hydrocarbon gases at a sample of the extracted gas;
(b) measuring the absorption of the first laser beam by the sample of gas;
(c) directing a second laser beam at the sample of gas at a frequency weakly absorbed by methane gas;
(d) measuring the absorption of the second laser beam by the sample of gas;
(e) calculating the concentration of methane gas present in the gas sample based on the absorption of the first and second laser beams by the sample of gas;
(f) directing a third laser beam at a sample of such gas at a frequency strongly absorbed by an additional type of hydrocarbon gas;
(g) measuring the absorption of the third laser beam;
and
(h) calculating the concentration of the additional type of hydrocarbon gas present in the sample of gas based on the level of absorption of the third laser beam.

6 more elements

A method of determining the composition of hydrocarbon gases in a sample of gas, comprising the steps of:

(a) directing a first laser beam at a frequency strongly absorbed by methane gas and other hydrocarbon gases at the sample of gas;
(b) measuring the absorption of the first laser beam by the sample of gas;
(c) directing a second laser beam at the sample of gas at a frequency weakly absorbed by methane gas;
(d) measuring the absorption of the second laser beam by the sample of gas;
(e) calculating the concentration of methane gas present in the gas sample based on the absorption of the first and second laser beams by the sample of gas;
(f) directing a third laser beam at a sample of such gas at a frequency strongly absorbed by propane gas;
(g) measuring the absorption of the third laser beam by the sample of gas;
(h) calculating the concentration of propane gas present in the sample of gas based on the level of absorption of the third laser beam;
(i) directing a fourth laser beam at the sample of gas at a frequency strongly absorbed by n-butane gas;
(j) measuring the absorption of the fourth laser beam by the sample of gas;
and
(k) calculating the concentration of n-butane gas present in the sample of gas based on the absorption of the fourth laser beam.

9 more elements

A method for determining the constituent hydrocarbon gas composition of gases recovered from drilling mud removed from an oil or natural gas well or from effluent recovered from a coal bore hole, comprising the steps of:

(a) passing a flowing stream of the gas sample recovered from the drilling mud or effluent through a first photoacoustic absorption cell;
(b) directing a first laser beam at a frequency strongly absorbed by all common hydrocarbon gases and vapors at the first photoacoustic absorption cell;
(c) sensing the energy of the acoustic disturbance generated within the first photoacoustic cell from absorption of the energy of the first laser beam by the gas sample stream;
(d) using the energy of the acoustic disturbance induced by the first laser beam to compute the total amount of hydrocarbon gases and vapors present in the sample;
(e) passing a flowing stream of the sample of gas through a second photoacoustic cell;
(f) directing a second laser beam at a second photoacoustic cell at a frequency weakly absorbed by methane and absorbed to about the same degree as the frequency of the first laser beam by the other hydrocarbon gases;
(g) sensing the energy of the acoustic disturbance generated within the second photoacoustic cell from absorption of the energy of the second laser beam by the gas sample stream;
(h) using the energy of the acoustic disturbance induced by the second laser beam to compute the amount of hydrocarbon gas less methane gas present in the gas sample;
(i) passing a flowing stream of the gas sample through a third photoacoustic cell;
(j) directing a third laser beam at the third photoacoustic cell at a frequency strongly absorbed by propane gas;
(k) sensing the energy of the acoustic disturbance generated within the third acoustic cell from absorption of the energy of the third laser beam by the gas sample;
(l) using the energy of the acoustic disturbance induced by the third laser beam to compute the amount of propane gas in the gas sample;
(m) directing a fourth laser beam at the third acoustic cell at a frequency strongly absorbed by n-butane gas;
(n) sensing the energy of the acoustic disturbance generated within the third photoacoustic cell from absorption of the energy of the fourth laser beam by the gas sample;
and
(o) using the energy of the acoustic disturbance induced by the fourth laser beam to compute the amount of n-butane gas contained in the gas sample.

13 more elements

Dependencies are inferred from the claim text.

Method and apparatus for analyzing components of hydrocarbon gases recovered from oil, natural gas and coal drilling operations

Life of this patent

Method and apparatus for analyzing components of hydrocarbon gases recovered from oil, natural gas and coal drilling operations

Life of this patent

Abstract

Claims88