Tracer compositions
The present disclosure relates to tracing gas flow in a hydrocarbon reservoir with compositions including a degradable polymer and a detectable component. An exemplary method includes introducing a tracer composition at a first location in the reservoir, contacting the tracer composition with the reservoir to hydrolyze the degradable polymer, and detecting a degraded tracer composition including the hydrolyzed polymer and the detectable component in a gas sample collected at a second location in the reservoir.
1 . A method of tracing gas flow in a hydrocarbon reservoir, comprising:
introducing a tracer composition at a stimulation site in a surface of a subterranean formation, the subterranean formation including the hydrocarbon reservoir, wherein the tracer composition comprises a degradable polymer and a detectable component;
contacting the tracer composition with the hydrocarbon reservoir to hydrolyze the degradable polymer to yield a degraded tracer composition that is carried by the gas flow through the hydrocarbon reservoir to a gas pipeline in fluid communication with a producing site at the surface of the subterranean formation; and
detecting the degraded tracer composition in a gas sample flowing through the gas pipeline collected at the producing site in the subterranean formation to trace a gas flow pattern between the stimulation site and the producing site of the subterranean formation, wherein the degraded tracer composition comprises a hydrolyzed polymer and the detectable component;
wherein the detectable component comprises:
a particulate metal oxide;
a fluorescent dye, disposed on a surface of the particulate metal oxide;
wherein the tracer composition comprises:
from about 0.001 wt % to about 0.1 wt % of the fluorescent dye;
from about 10 wt % to about 60 wt % of the particulate metal oxide; and
from about 40 wt % to about 90 wt % of the degradable polymer.
2 . The method of claim 1 , wherein the degradable polymer comprises a thermoplastic.
3 . The method of claim 2 , wherein the thermoplastic comprises a poly(lactic acid).
4 . The method of claim 1 , wherein the degradable polymer comprises a thermoplastic polyester elastomer.
5 . The method of claim 4 , wherein the thermoplastic polyester elastomer comprises a block copolymer comprising a hard segment and a soft segment.
6 . The method of claim 5 , wherein the hard segment comprises ethylene terephthalate, propylene terephthalate, butylene terephthalate, or any combination thereof.
7 . The method of claim 5 , wherein the soft segment comprises a polyether, a polyester, a polycarbonate, or any combination thereof.
8 . The method of claim 7 , wherein the soft segment comprises a polyether, and the polyether comprises a polyoxyalkylene glycol.
9 . The method of claim 1 , wherein the fluorescent dye is covalently bonded to the surface of the particulate metal oxide by a dehydration reaction of the fluorescent dye with an —OH group on the surface of the particulate metal oxide, wherein the particulate metal oxide comprises aluminum hydroxide and the fluorescent dye is selected from the group consisting of fluorescein and rhodamine B.
10 . The method of claim 1 , wherein the metal oxide comprises aluminum hydroxide.
11 . The method of claim 1 , wherein an average size of the particulate metal oxide is about 10 nm to about 10 μm; and
wherein the tracer composition includes about 20 wt % to 80 wt % of the particulate metal oxide.
12 . The method of claim 1 , wherein the tracer composition comprises an extrudate of the degradable polymer and the detectable component.
13 . The method of claim 1 , wherein the tracer composition comprises particles having an average size of at least about 5 mm.
14 . The method of claim 13 , wherein the particles of the tracer composition comprise pellets or fibers.
15 . The method of claim 14 , wherein the particles comprise fibers having an average length of at least about 4 mm.
16 . The method of claim 13 , wherein the degraded tracer composition comprises particles having an average size of less than about 2 mm.
17 . The method of claim 16 , wherein the particles of the degraded tracer composition comprise a powder.
18 . The method of claim 1 , wherein introducing the tracer composition comprises pumping a stimulation fluid comprising the tracer composition into the reservoir at the first location.
19 . The method of claim 18 , wherein the stimulation fluid comprises an acid.
20 . The method of claim 1 , wherein detecting the degraded tracer composition comprises capturing the degraded tracer composition on a filter.
21 . The method of claim 1 , wherein detecting the degraded tracer composition comprises detecting the fluorescent dye with a fluorometer.
22 . The method of claim 1 , wherein detecting the degraded tracer composition comprises detecting the metal oxide with an X-ray fluorescence spectrometer.
23 . A method of tracing gas flow in a hydrocarbon reservoir, comprising:
introducing a tracer composition at a first location in the reservoir, wherein the tracer composition comprises a degradable polymer and a detectable component;
contacting the tracer composition with the reservoir to hydrolyze the degradable polymer; and
detecting a degraded tracer composition in a gas sample collected at a second location in the reservoir, wherein the degraded tracer composition comprises the hydrolyzed polymer and the detectable component;
wherein the detectable component comprises:
a particulate metal oxide; and
a fluorescent dye, disposed on a surface of the particulate metal oxide; and
wherein the fluorescent dye is covalently bound to the surface of the particulate metal oxide by a dehydration reaction of the fluorescent dye with an —OH group present on the surface of the particulate metal oxide, wherein the fluorescent dye comprises rhodamine B and the particulate metal oxide comprises aluminum hydroxide.