Oil and Gas Fracture Liquid Tracing with Oligonucleotides

Abstract

Methods of tracing fracking liquid in oil or gas bearing formations using plural unique oligonucleotide markers. Method includes pumping the plural volumes of fracking liquid, each marked with a unique oligonucleotide, into the formation, thereby defining plural fracture zones in the formation, and, pumping fluids out of the formation while taking plural fluid samples. Then, analyzing the concentration of the unique oligonucleotides in each of the plural fluid samples, and, calculating the ratio of each of the plural volumes of fracking liquid recovered for each of the plural fluid samples according to the concentration of the unique oligonucleotides present in each of the plural samples. And, then, establishing the quantity of the plural volumes of fracking liquids removed from the plural fracture zones.

What is claimed is: 
     
         1 . A method of tracing liquid in oil or gas bearing formations using unique oligonucleotide markers, comprising the steps of:
 pumping a volume of liquid, marked with a unique oligonucleotide, into the formation, thereby defining a zone in the formation that has been marked with the unique oligonucleotide;   pumping fluids out of the formation while taking plural fluid samples;   analyzing the concentration of the unique oligonucleotide in each of the plural fluid samples;   calculating the ratio of the volume of liquid marked with the unique oligonucleotide recovered for each of the plural fluid samples according to the concentration of the unique oligonucleotide present in each of the plural samples, and   thereby establishing the quantity of the volume of liquid marked with the unique oligonucleotide removed from the zone for each of the plural samples.   
     
     
         2 . The method of  claim 1 , and wherein the unique oligonucleotide marker is biotinylated, and wherein said analyzing the concentration step further comprises:
 immobilizing avidin or streptavidin onto magnetic particles;   mixing the magnetic particles with at least one of the plural fluid samples, thereby enabling the formation of non-covalent bonds between the biotinylated oligonucleotides and the immobilized avidin or streptavidin;   removing the magnetic particles from the at least one of the plural fluid samples by magnetic attraction, thereby concentrating the sample, and measuring the quantity of the unique oligonucleotides.   
     
     
         3 . The method of  claim 2 , and wherein:
 the unique oligonucleotides are biotinylated by binding biotin to the 5′-end of the oligonucleotides.   
     
     
         4 . The method of  claim 2 , and wherein said measuring step further comprises the steps of:
 determining the atomic mass and quantity of the unique oligonucleotides in the sample using a matrix-assisted laser desorption/ionization with time of flight mass spectrometer.   
     
     
         5 . The method of  claim 2 , further comprising the step of:
 agitating the at least one of the plural fluid samples and the magnetic particles to facilitate the formation of non-covalent bonds.   
     
     
         6 . The method of  claim 2 , and wherein the removing step is accomplished by inserting a magnet into the sample, and further comprising the step of:
 rinsing the magnetic particles prior to said measuring step.