Method and apparatus for determining in situ hydrocarbon characteristics including hydrogen density
AssigneeSchlumberger Technology Corporation
InventorJohn J. Ullo
Life of this patent
Estimating the term…
Abstract
Method and apparatus for determining the hydrogen and carbon densities of oil in situ in a subsurface geological formation are proposed which utilize the response of a neutron porosity tool to some oils. Apparent porosity derived from a neutron porosity investigation tool, which measures spatial neutron flux distribution, is compared to the porosity derived from a second investigating tool whose response is not or at least is less sensitive, say, to the hydrogen density of the formation fluid than is the neutron porosity tool. The magnitude of the difference is indicative of the hydrogen and carbon densities of the oil.
Claims20
A method for investigating characteristics of the oil within a geological formation while it remains in situ, said method comprising the steps of:
- a. irradiating said geological formation with neutrons;
- b. detecting the resultant neutron flux distribution and generating therefrom a first signal indicative of formation porosity and hydrogen density of the fluid in said formation;
- c. deriving from said geological formation a second signal indicative of formation porosity but which is less affected by the nature of the pore fluid, whether it be water or liquid hydrocarbon, than said first signal;
- d. combining said first and second signals to generate a signal proportional to the differential therebetween;
- and
- e. determining from said differential signal a signal indicative of the hydrogen density of said oil.
A method for investigating characteristics of the oil within a geological formation while it remains in situ, said method comprising the steps of:
- a. irradiating said geological formation with neutrons having a first average energy level;
- b. detecting neutrons resulting from step a. and generating a signal indicative thereof;
- c. irradiating said geological formation with neutrons having a second average energy level different from said first average energy level;
- d. detecting neutrons resulting from step c. and generating a signal indicative thereof;
- e. combining the signals of steps b. and d. in order to obtain a differential signal said differential being an indication of the presence of oil or of water;
- and
- f. determining from said differential signal a signal indicative of the hydrogen density of said oil.
A method for investigating characteristics of the oil within a geological formation while it remains in situ, said method comprising the steps of:
- a. irradiating said geological formation with neutrons;
- b. detecting the neutron flux distribution resulting from step a. and generating a signal indicative of formation porosity therefrom;
- c. irradiating said geological formation with gamma rays;
- d. detecting the gamma ray flux resulting from step c. and generating a signal indicative of formation porosity therefrom;
- e. comparing the porosity signals of steps b. and d. in order to obtain a signal indicative of the difference there-between;
- and
- f. determining from said difference signal a signal indicative of the hydrogen density of said oil.
A method for investigating characteristics of the oil within a geological formation while it remains in situ, said method comprising the steps of:
- a. irradiating said geological formation with neutrons;
- b. detecting the neutron flux distribution resulting from step a. and generating a signal indicative of formation porosity therefrom;
- c. transmitting sound waves into said geological formation;
- d. detecting sound waves returning from the formation resulting from step c. and generating a signal indicative of formation porosity therefrom;
- e. comparing the porosity signals of steps b. and d. in order to obtain an indication of the difference therebetween;
- and
- f. determining from said difference, an indication of the hydrogen density of the oil in said formation.
An apparatus for investigating characteristics of the oil within a geological formation while it remains in situ, said apparatus comprising:
- a. means for irradiating said geological formation with neutrons;
- b. means for detecting the resultant neutron flux distribution and generating therefrom a first signal indicative of formation porosity and hydrogen density of the fluid in said formation;
- c. means for deriving from said geological formation a second signal indicative of formation porosity but which is less affected by the nature of the pore fluid, whether it be water or liquid hydrocarbon, than said first signal;
- d. means for combining said first and second signals to generate a signal proportional to the differential therebetween;
- and
- e. means for determining from said differential signal a signal indicative of the hydrogen density of said oil.
An apparatus for investigating characteristics of the oil within a geological formation while it remains in situ, said apparatus comprising:
- a. means for irradiating said geological formation with neutrons having a first average energy level;
- b. means for detecting the neutron flux distribution resulting from said neutrons having a first average energy level and generating a first signal indicative thereof;
- c. means for irradiating said geological formation with neutrons having a second average energy level different from said first average energy level;
- d. means for detecting the neutron flux distribution resulting from said neutrons having a second average energy level and generating a second signal indicative thereof;
- e. means for combining said first and second signals in order to obtain a differential signal said differential being an indication of the presence of oil or of water;
- and
- f. means for determining from said differential signal a signal indicative of the hydrogen density of said oil.
An apparatus for investigating characteristics of the oil within a geological formation while it remains in situ, said apparatus comprising:
- a. means for irradiating said geological formation with neutrons;
- b. means for detecting the neutron flux distribution and generating a first signal indicative of formation porosity therefrom;
- c. means for irradiating said geological formation with gamma rays;
- d. means for detecting the gamma ray flux and generating a second signal indicative of formation porosity therefrom;
- e. means for comparing said and second porosity signals in order to obtain a signal indicative of the difference therebetween;
- and
- f. means for determining from said difference signal a signal indicative of the hydrogen density of said oil.
An apparatus for investigating characteristics of the oil within a geological formation while it remains in situ, said apparatus comprising:
- a. means for irradiating said geological formation with neutrons;
- b. means for detecting the neutron flux distribution and generating a first signal indicative of formation porosity therefrom;
- c. means for transmitting sound waves into said geological formation;
- d. means for detecting sound waves returning from the formation and generating a second signal indicative of formation porosity therefrom;
- e. means for comparing said first and second porosity signals in order to obtain an indication of the difference therebetween;
- and
- f. means for determining from said difference, an indication of the hydrogen density of the oil in said formation.
Dependencies are inferred from the claim text.