Partially degradable particulates as time-released tracers for acidized and fractured gas wells

Abstract

A method for monitoring gas production in a subterranean formation includes introducing a polymer composite particle having a degradable portion and a non-degradable portion including a tracer into a stimulation fluid and injecting the stimulation fluid into the subterranean formation to a treatment stage of a treatment zone. The treatment stage has at least one opening that the polymer composite particle may flow into and remain inside. The polymer composite particle may be exposed to moisture at a downhole temperature while inside the at least one opening. The moisture may degrade the degradable portion of the polymer composite particle, thereby releasing the non-degradable portion including the tracer. Produced gas that includes the non-degradable portion including the tracer may be recovered from the subterranean formation and the tracer may be correlated to the treatment stage of the treatment zone of the subterranean formation.

1 . A method for monitoring gas production in a subterranean formation comprising:
 introducing a polymer composite particle having a degradable portion and a non-degradable portion into a stimulation fluid, wherein the non-degradable portion comprises a tracer encapsulated by a non-degradable polymer,   wherein the degradable portion comprises a polymer that has hydrolyzable bonds in the backbone;   injecting the stimulation fluid comprising the polymer composite particle into the subterranean formation to a treatment stage of a treatment zone comprising at least one opening, wherein the polymer composite particle flows into and remains inside the at least one opening;   maintaining the polymer composite particle inside the at least one opening for an amount of time during which the polymer composite particle is exposed to moisture at a downhole temperature, wherein the moisture degrades the degradable portion of the polymer composite particle, thereby releasing the non-degradable portion comprising the tracer encapsulated by the non-degradable polymer;   recovering produced gas from the subterranean formation, wherein the produced gas comprises a gaseous phase from the treatment stage of the treatment zone of the subterranean formation and the non-degradable portion comprising the tracer encapsulated by the non-degradable polymer;   determining a presence of the non-degradable portion comprising the tracer encapsulated by the non-degradable polymer in the produced gas; and   correlating the presence of the non-degradable portion comprising the tracer encapsulated by the non-degradable polymer to the treatment stage of the treatment zone of the subterranean formation.   
     
     
         2 . The method of  claim 1 , further comprising:
 injecting a second stimulation fluid comprising a second polymer composite particle having a degradable portion and a non-degradable portion comprising a second tracer encapsulated by a non-degradable polymer into the subterranean formation to a second treatment stage of the treatment zone comprising at least one opening, wherein the second polymer composite particle flows into and remains inside the at least one opening;   maintaining the second polymer composite particle inside the at least one opening of the second treatment stage for an amount of time during which the second polymer composite particle is exposed to moisture at a downhole temperature, wherein the moisture degrades the degradable portion of the second polymer composite particle, thereby releasing the non-degradable portion comprising the second tracer encapsulated by the non-degradable polymer;   detecting a presence of the non-degradable portion comprising the second tracer encapsulated by the non-degradable polymer in the produced gas; and   correlating the presence of the non-degradable portion comprising the second tracer encapsulated by the non-degradable polymer to the second treatment stage of the treatment zone.   
     
     
         3 . The method of  claim 1 , wherein the degradable portion of the polymer composite particle is a degradable polymer comprising hydrolyzable bonds. 
     
     
         4 . The method of  claim 3 , wherein the degradable polymer is selected from the group consisting of polyesters, polyester copolymers, polyamides, polyamide copolymers, polyvinyl alcohols, polyvinyl alcohol derivates, polyurethanes, polyurethane copolymers, and combinations thereof. 
     
     
         5 . The method of  claim 1 , wherein the non-degradable portion of the polymer composite particle is a non-degradable polymer selected from the group consisting of polyethylene, polybutylene and ethylene-vinyl acetate, polystyrene, acrylonitrile butadiene styrene, polyacrylonitrile-styrene-acrylic, and combinations thereof. 
     
     
         6 . The method of  claim 1 , wherein the tracer is selected from the group consisting of tetrachloroisoindolinone orange, perylene red, quinacridone red, phthalocyanine blue, phthalocyanine green, disazo diarylide yellows, and combinations thereof. 
     
     
         7 . The method of  claim 1 , wherein the tracer is selected from the group consisting of ZnO, Fe 2 O 3 , CO 2 O 3 , Ni 2 O 3 , Cr 2 O 3 , CuO, MnO x , ZrO 2 , TiO 2 , ZnS, Ce 2 S 3 , and combinations thereof. 
     
     
         8 . The method of  claim 1 , wherein the polymer composite particle has an average particle size ranging from 10 microns to 10 millimeters. 
     
     
         9 . The method of  claim 1 , wherein the non-degradable portion of the polymer composite particle has an average particle size ranging from 100 nm to 300 microns. 
     
     
         10 . The method of  claim 1 , wherein the stimulation fluid is selected from the group consisting of an acidizing fluid, an organic acid, a fracturing fluid, a hydraulic fracturing fluid, an emulsified acid, a viscoelastic surfactant, a foamed fluid, a linear gel, a crosslinked gel, and combinations thereof. 
     
     
         11 . The method of  claim 1 , wherein the opening is a fracture, a wormhole, or a pore. 
     
     
         12 . The method of  claim 1 , wherein the amount of time is from 1 week to 12 weeks. 
     
     
         13 . The method of  claim 1 , wherein the subterranean formation comprises up to 80 treatment stages and wherein the method further comprises:
 injecting a stimulation fluid comprising a distinct polymer composite particle having a degradable portion and a non-degradable portion comprising a distinct tracer encapsulated by a non-degradable polymer into the subterranean formation at each treatment stage, such that up to 80 distinct polymer composite particles are injected into the subterranean formation, wherein each treatment stage comprises at least one opening and wherein each distinct polymer composite particle flows into and remains inside the at least one opening;   maintaining each of the up to 80 distinct polymer composite particles inside the at least one opening of each treatment stage for an amount of time during which each distinct polymer composite particle is exposed to moisture at a downhole temperature, wherein the moisture degrades the degradable portion of each distinct polymer composite particles, thereby releasing the non-degradable portion comprising the distinct tracer encapsulated by the non-degradable polymer, such that up to 80 non-degradable portions, each comprising a distinct tracer are released at the same or different times;   detecting a presence of the distinct tracer of each of the up to 80 non-degradable portions in the produced gas; and   correlating the presence of the distinct tracer encapsulated by the non-degradable polymer of each of the up to 80 non-degradable portions to one of the up to 80 treatment stages of the subterranean formation.   
     
     
         14 . A method comprising:
 extruding a degradable polymer and a non-degradable polymer comprising a tracer encapsulated by the non-degradable polymer to provide a polymer composite; and   introducing the polymer composite into a stimulation fluid.   
     
     
         15 . The method of  claim 14 , wherein the polymer composite is in the form of a particle or a fiber. 
     
     
         16 . The method of  claim 14 , further comprising coating the polymer composite onto a proppant. 
     
     
         17 . The method of  claim 16 , wherein the polymer composite is present in an amount of 1 to 100 wt % based on the weight of the proppant. 
     
     
         18 . A composition comprising:
 a polymer composite particle comprising:
 a degradable portion; 
 a non-degradable portion comprising a tracer,
 wherein the tracer is encapsulated by the non-degradable polymer; and 
 
   stimulation fluid.   
     
     
         19 . The composition of  claim 18 , wherein the non-degradable portion of the polymer composite particle is a non-degradable polymer selected from the group consisting of polyethylene, polybutylene and ethylene-vinyl acetate, polystyrene, acrylonitrile butadiene styrene, polycarbonate, polyacrylonitrile-styrene-acrylic, and combinations thereof. 
     
     
         20 . The composition of  claim 18 , wherein the degradable portion is a degradable polymer comprising hydrolyzable bonds. 
     
     
         21 . The composition of  claim 20 , wherein the degradable polymer is selected from the group consisting of polyesters, polyester copolymers, polyamides, polyamide copolymers, polyvinyl alcohols, polyvinyl alcohol derivates, polyurethanes, polyurethane copolymers, and combinations thereof. 
     
     
         22 . The composition of  claim 18 , wherein the tracer is selected from the group consisting of tetrachloroisoindolinone orange, perylene red, quinacridone red, phthalocyanine blue, phthalocyanine green, disazo diarylide yellows, and combinations thereof.