Tracer method and apparatus

Abstract

A method of monitoring the flow of fluid within or from an oil or gas reservoir includes inserting a solid tracer into the reservoir. The tracer comprises at least one metal selected from caesium, niobium, tantalum, tellurium, terbium, lanthanum, gold, iridium, osmium, silver, platinum, palladium, rhenium, ruthenium, rhodium, hafnium, indium, a metal of the Lanthanide series of the periodic table, or a salt thereof. A sample of fluid within or flowing from the reservoir is collected and analysed to determine the amount of the tracer contained in the sample. A perforation tool allows for insertion of the tracer within the formation.

1 . A method of monitoring the flow of fluid within or from a reservoir comprising the steps of inserting in said reservoir a solid tracer comprising at least one non-radioactive metal selected from the group consisting of caesium, niobium, tantalum, tellurium, terbium, lanthanum, gold, iridium, osmium, silver, platinum, palladium, rhenium, ruthenium, rhodium, hafnium, indium, a metal of the Lanthanide series of the periodic table, and a salt thereof, thereafter collecting a sample of fluid within or flowing from the reservoir and analysing said sample to determine an amount of said tracer contained in the sample, wherein the tracer is inserted into the reservoir by means of a perforation tool. 
   
   
       2 . A method as claimed in  claim 1 , wherein the tracer comprises caesium, niobium, tantalum, tellurium, terbium, europium, platinum or rhodium or a salt thereof. 
   
   
       3 . A method as claimed in  claim 1 , wherein the tracer comprises a water-soluble salt of at least one of said non-radioactive metals. 
   
   
       4 . A method as claimed in  claim 1 , wherein the tracer comprises a hydrocarbon-soluble salt of at least one of said non-radioactive metals. 
   
   
       5 . A method as claimed in  claim 1 , wherein the tracer comprises at least one of said non-radioactive metals in elemental form. 
   
   
       6 . A method as claimed in  claim 1 , wherein the tracer is in a physical form of a disc, rod, wire or coating. 
   
   
       7 . A method as claimed in  claim 1 , wherein the tracer is in a form of finely divided particles of said non-radioactive metal or of a salt of the at least one non-radioactive metal. 
   
   
       8 . A method as claimed in  claim 7 , wherein the particles are formed into a shaped unit. 
   
   
       9 . A method as claimed in  claim 1 , wherein the reservoir is a subterranean oil and/or natural gas reservoir. 
   
   
       10 . (canceled) 
   
   
       11 . A perforation tool comprising an elongate body having a central longitudinal axis, a control means, deployment means and at least one explosive charge mounted on or within said body and associated with detonation means, said charge being arranged to direct energy explosively and outwardly from the elongate body upon detonation, and at least one tracer material mounted on or within said body within the path of said explosive energy, wherein the tracer material is solid and comprises at least one non-radioactive metal selected from the group consisting of caesium, niobium, tantalum, tellurium, terbium, lanthanum, gold, iridium, osmium, silver, platinum, palladium, rhenium, ruthenium, rhodium, hafnium, indium, a metal of the Lanthanide series of the periodic table, and a salt thereof. 
   
   
       12 . A perforation tool as claimed in  claim 11 , wherein the tracer comprises caesium, niobium, tantalum, tellurium, terbium, europium, platinum or rhodium or a salt thereof. 
   
   
       13 . A perforation tool as claimed in  claim 11 , wherein the tracer comprises a water-soluble salt of at least one of said non-radioactive metals. 
   
   
       14 . A perforation tool as claimed in  claim 11 , wherein the tracer comprises a hydrocarbon-soluble salt of at least one of said non-radioactive metals. 
   
   
       15 . A perforation tool as claimed in  claim 11 , wherein the tracer comprises at least one of said non-radioactive metals in elemental form. 
   
   
       16 . A perforation tool as claimed in  claim 11 , wherein the tool comprises an outer sleeve covering the explosive charges and wherein the tracer is located in one or more indentations formed in the outer sleeve aligned with one or more of the explosive charges. 
   
   
       17 . A perforation tool as claimed in  claim 11 , wherein the tracer is located spaced away from a charge between said charge and an outer sleeve of said tool in the intended path of the explosive blast so that at least some of the tracer material is carried into the reservoir formation with the explosive gases when the charge is detonated.