Method and system for monitoring a well treatment

Abstract

The invention may provide methods of characterising and/or optimising a well treatment. The method comprises calculating, estimating and/or determining at least one spatial or temporal tracer distribution moment for at least one tracer in a well before the well treatment and calculating, estimating and/or determining at least one spatial or temporal tracer distribution moment for the at least one tracer introduced into the well at a later stage or later portion of the well treatment or after at least well treatment stage has been completed or approaching completion. The method comprises comparing the at least one spatial or temporal tracer distribution moment of the tracers to estimate at least one characteristic of the well treatment.

1 . A method of characterising a well treatment, the method comprising:
 calculating, estimating and/or determining at least one spatial or temporal tracer distribution moment for at least one tracer in the well before a well treatment and/or in an early portion of a well treatment;   calculating, estimating and/or determining at least one spatial or temporal tracer distribution moment for the at least one tracer introduced into the well at a later stage or later portion of the well treatment or after at least well treatment stage has been completed or approaching completion;   comparing the at least one spatial or temporal tracer distribution moment of the at least two tracers to estimate at least one characteristic of the well treatment.   
     
     
         2 . The method according to  claim 1  wherein the well treatment is selected from the group comprising well stimulation treatment, acidizing treatment, matrix acidizing treatment, fracturing treatment, hydraulic fracturing treatment, fracture acidizing treatment, enhanced oil recovery treatment, and/or water control treatment. 
     
     
         3 . The method according to  claim 1  comprising introducing at least one tracer into a well before and/or with the well treatment. 
     
     
         4 . The method according to  claim 1  comprising calculating, estimating and/or determining at least one spatial or temporal tracer distribution moment for at least one tracer in the well before the well treatment from historical tracer injection and/or production associated with production from the reservoir. 
     
     
         5 . The method according to  claim 1  comprising introducing each of the two or more tracers into the well by injecting the two or more tracers into the well from surface or from a downhole device. 
     
     
         6 . The method according to  claim 1  comprising introducing at least one tracer into the well by releasing tracer from tracer sources installed, arranged or positioned in the well. 
     
     
         7 . The method according to  claim 1  comprising introducing two or more tracer into the same injector well or different injector wells. 
     
     
         8 . The method according to  claim 1  comprising introducing two or more tracers into an injector well, a production well or a combination of at least one injector well and production well. 
     
     
         9 . The method according to  claim 1  comprising associating a difference or change between the at least one spatial or temporal tracer distribution moment for the two of more tracers with a characteristic of the well treatment. 
     
     
         10 . The method according to  claim 1  wherein the at least one moment is selected from a zero order moment, a first order moment, a second order moment, and/or a higher order moment. 
     
     
         11 . The method according to  claim 1  comprising analysing a measured tracer concentration data set for each of the two or more tracers wherein the measured tracer concentration data set is tracer concentration as a function of time, tracer concentration as a function of space and/or a residence time distribution. 
     
     
         12 . The method according to  claim 1  comprising creating a tracer curve from the measured tracer concentration as a function of time and comparing the tracer curves of the two or more tracers to assess the well stimulation treatment. 
     
     
         13 . The method according to  claim 12  comprising calculating an area under the tracer curve to calculate the at least one moment of measured tracer data set and comparing the area under the tracer curve for each of the two or more tracers. 
     
     
         14 . The method according to  claim 1  comprising calculating a swept volume for each of the two or more tracers and comparing the swept volume of each of the two or more tracers. 
     
     
         15 . The method according to  claim 1  comprising calculating an arrival time characteristic for each of the two or more tracers and comparing the arrival time characteristic for the two or more tracers to assess a magnitude of change associated with the well stimulation treatment. 
     
     
         16 . The method according to  claim 1  comprising analysing the measured tracer concentration data to characterise and/or identify a flow type pattern selected from the group comprising a face dissolution, conical wormhole, dominant wormhole, ramified wormhole, uniform dissolution, an etch pattern, a near-wellbore dissolution, heterogeneous etch channel, channels, planar fractures, complex fractures and/or cracks. 
     
     
         17 . The method according to  claim 1  comprising identifying and/or characterising flow patterns by comparing a measured tracer response curve with a library of tracer response curves associated with various flow type patterns. 
     
     
         18 . The method according to  claim 1  comprising improving production forecasting based on characterising flow patterns after the well treatment. 
     
     
         19 . The method according to  claim 1  wherein the tracers are selected from the group comprising water tracers, oil tracers, gas tracers, or tracers deployed as solids such as in a polymer matrix, impregnated proppant, or fluid loss material. 
     
     
         20 . The method according to  claim 1  introducing at least one distinctive tracer into a well before and/or with a further well treatment and introducing a different tracer into the well at a later stage or later portion of the well treatment or after at least well treatment stage has been completed or approaching completion and comparing the at least one spatial or temporal moment of the tracers to estimate at least one characteristic of the further well treatment. 
     
     
         21 . A method of optimising a well treatment, the method comprising:
 calculating, estimating and/or determining at least one spatial or temporal moment for at least one tracer in the well before the well treatment and/or in an early portion of the well treatment;   calculating, estimating and/or determining at least one spatial or temporal moment for the at least one tracer introduced into the well at a later stage or later portion of the well profile modification treatment or after at least well treatment stage has been completed or approaching completion;   comparing the at least one spatial or temporal moment of the at least two tracers to estimate at least one characteristic of the well treatment.   
     
     
         22 . The method according to  claim 21  comprising optimising the well treatment by adjusting one or more parameters selected from the group comprising stimulation fluid type, fluid viscosity, fluid reactivity, acid concentration, additive concentration, injection volume, injection rates, pulsing, proppant concentrations, fluid loss additive concentration and/or diverting agents. 
     
     
         23 . The method according to  claim 21  comprising characterising changes in reservoir flow patterns and optimising the well treatment by adjusting additional treatment and/or changing the treatment design in subsequent stages or subsequent wells. 
     
     
         24 . An interpretation method for a well treatment of a well comprising;
 providing tracer data from a producing well after a well treatment and/or in the early portion of the well treatment;   wherein the tracer data comprises tracer concentration over time of two or more tracers in the production flow; wherein the two or more tracers were introduced into the well at known times of the well treatment;   analysing the tracer data to estimate at least one characteristic of the well treatment based on the presence and/or concentration of tracers in the samples.   
     
     
         25 . A system for characterising and/or optimising a well treatment, the system comprises:
 two or more tracer sources each with a distinct tracer material;   at least one tracer release mechanism;   at least one well stimulation fluid;   at least one pump apparatus to pump or inject the at least one well stimulation fluid;   and at least one sampling device configured to collect at least one sample of well fluid at a known sampling location.