Tracing flow of petroleum in underground reservoirs

• US 3,993,131 A
• Filed: 11/03/1975
• Issued: 11/23/1976
• Est. Priority Date: 11/03/1975
• Status: Expired due to Term

• Current Assignee: Cities Service Co. (PDV Holding, Inc.)
• Original Assignee: Cities Service Co. (PDV Holding, Inc.)
• Inventors: Riedel, E. Frederic
• Primary Examiner(s): Novosad, Stephen J.
• Application Number:
  US05/628,014
• Time in Patent Office: 386 Days
• Field of Search: 166/252, 23/230 EP, 73/155, 195/DIG. 11, 195/103.5 P, 324/.5 A, 324/.5 AC, 324/2, 324/11
• US Class Current: 436/27
• CPC Class Codes: C07D 207/46 with hetero atoms directly attached to the ring nitrogen atom
• CPC Class Codes: C07D 211/94 Oxygen atom, e.g. piperidine N-oxide
• CPC Class Codes: E21B 43/16 Enhanced recovery methods for obtaining hydrocarbons
• CPC Class Codes: E21B 47/11 using tracers; using radioactivity
• CPC Class Codes: E21B 49/00 Testing the nature of borehole walls; Formation testing; Methods or apparatus for obtaining samples of soil or well fluids, specially adapted to earth drilling or wells
• CPC Class Codes: G01V 5/08 using primary nuclear radiation sources or X-rays , e.g. for inducing radioactivity; investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays, neutrons G01N23/00
• CPC Class Codes: Y10T 436/24 Nuclear magnetic resonance, electron spin resonance or other spin effects or mass spectrometry

Abstract

The flow path of petroleum in underground reservoirs is monitored by injecting a stable free radical, or spin label, into the reservoir as a tracer which becomes detectable in a sample taken from a producing well. Detection of the spin label is by electron spin resonance (ESR) spectroscopy. Spin label tracers are, on the average, detectable at dilutions 1 million times lower than is possible with standard chemical tracing methods.

Claims

1. A method for tracing the flow of fluid contained in an underground reservoir which comprises:

a. injecting into said reservoir at a first point a stable free radical and wherein the stable free radical is injected as a tracer,

b. removing a fluid sample from said reservoir at a second point following injection of said stable free radical, and

c. analyzing said sample by electron spin resonance (ESR) spectroscopy for detecting presence of a stable free radical therein.

2. Method as in claim 1 wherein said tracer is injected into the reservoir while contained in water.

3. Method as in claim 2 wherein said reservoir contains liquid petroleum, a drive fluid comprising water is pumped into the reservoir through an injection well at said first point for driving the liquid petroleum toward a producing well at said second point, and wherein said tracer is incorporated within the water of said drive fluid that is pumped into the reservoir.

4. Method as in claim 1 wherein said tracer comprises a stable free radical selected from the group consisting of nitroxide, hydrazide, and sterically hindered methyl.

5. Method as in claim 1 wherein said tracer is selected from the group consisting of:

a. 3-Carbamoyl-2,2,5,5-tetramethyl-3-pyrrolin-1-yloxy,

b. 3-Carbamoyl-2,2,5,5-tetramethylpyrrolidin-1-yloxy,

c. 4-Amino-2,2,6,6-tetramethylpiperidinooxy

d. 4-Hydroxy-2,2,6,6-tetramethylpiperidinooxy,

e. 4-Oxo-2,2,6,6-tetramethylpiperidinooxy.

6. Method as in claim 1 wherein said tracer is 2,2, diphenyl-1-picrylhydrazine (DPPH).

7. Method as in claim 1 wherein said tracer is triphenylmethane.

8. Method as in claim 1 wherein the amount of said tracer injected into said reservoir does not exceed about one gram-mole of the tracer for each 1.5 million barrels of fluid in the reservoir.

9. Method as in claim 1 wherein more than one stable free radical is injected into said reservoir at one or more points other than said first point.

10. Method as in claim 1 wherein more than one stable free radical is injected into said reservoir at said first point over one or more intervals of time.