Method and system for monitoring well flow characteristics

Abstract

The invention provides a method and system of characterising at least one fracture in a well system comprising a first well and at least a second well. The method comprising: forming at least one fracture from the first well to at least the second well and injecting at least a first tracer into the at least one fracture. The method comprises locating at least a second tracer in or at the at least one fracture. The method comprises producing fluid from the at least a second well, collecting samples of produced fluid and analysing the samples for the presence and/or concentration of tracer. The method comprises calculating at least one flow characteristic for the at least one fracture based on the presence and/or concentration of tracer in the samples.

1 . A method of characterising at least one fracture in a well system comprising a first well and at least a second well, the method comprising:
 forming at least one fracture from the first well to at least the second well;   injecting at least a first tracer into the at least one fracture;   locating at least a second tracer in or at the at least one fracture;   producing fluid from the at least a second well,   collecting samples of produced fluid;   analysing the samples for the presence and/or concentration of tracer;   calculating at least one flow characteristic for the at least one fracture based on the presence and/or concentration of tracer in the samples.   
     
     
         2 . The method according to  claim 1  comprising locating the second tracer at a location in the at least one fracture near the well bore of the first well or at the start of the at least one fracture. 
     
     
         3 . The method according to  claim 1  wherein the first tracer is a fracture tracer and the second tracer is a pulse tracer. 
     
     
         4 . The method according to  claim 1  wherein the first tracer and/or second tracer is selected from the group comprising chemical, fluorescent, phosphorescent, radioactive compounds, isotope, quantum dot, nanoparticles, or a combination thereof. 
     
     
         5 . The method according to  claim 1  comprising producing fluid from at least the second well to draw, pull and/or direct tracer and fluid in or through the at least one fracture into at least the second well. 
     
     
         6 . The method according to  claim 1  comprising forming two or more fractures; injecting at least one distinct first tracer into each fracture and locating at least one distinct second tracer at each fracture near the well bore of the first well or at the start of the at least one fracture. 
     
     
         7 . The method according to  claim 6  comprising producing fluid from at least the second well to draw, pull and/or direct at least one tracer located in two or more fractures into at least the second well. 
     
     
         8 . The method according to  claim 1  comprising drawing, pulling and/or directing flow from or through the at least one fracture into at least the second well at different flow rates. 
     
     
         9 . The method according to  claim 1  comprising controlling and/or modifying the production flow rate of fluid in the first well to a production rate less than or equal to a production rate of the at least a second well. 
     
     
         10 . The method according to  claim 1  comprising collecting samples of fluid from the at least a second well during a period of stable flow. 
     
     
         11 . The method according to  claim 1  wherein the well system or well combination comprises at least one treatment well and at least one production well. 
     
     
         12 . The method according to  claim 1  wherein the at least one fracture is formed or created by a well treatment 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. 
     
     
         13 . The method according to  claim 1  comprising characterising at least one fracture flow path; characterising at least one fracture flow path volume; characterising flow from, through and/or in each fracture in the well; characterising a fracture flow path volume of each fracture in the well system; characterising a hydraulic connection between the first well and at least a second well; characterising fracture flow path efficiency; characterising permeability between the first well and at least a second well; characterising porosity between the first well and at least a second well; characterising a hydraulic connection between the first well and at least a third or further well; and/or characterising permeability between the first well and at least a third or further well. 
     
     
         14 . The method according to  claim 1  comprising calculating at least one flow characteristic and/or at least one fracture characteristic selected from the group comprising fracture geometry; fracture width; hydraulic width; fracture aperture; hydraulic cross-sectional area; cross-sectional area of flow; percentage flow distribution; percentage flow distribution per stage; proppant transport capacity; fracture circulation volume; fracture circulation volume per stage; permeability; permeability per stage; porosity; porosity per stage; conductivity; conductivity per stage and/or fracture hydraulic conductivity. 
     
     
         15 . The method according to  claim 1  comprising injecting the first tracer into the at least one fracture during the formation of the at least one fracture. 
     
     
         16 . The method according to  claim 1  comprising collecting samples of the fluid at one or more sampling times. 
     
     
         17 . The method according to  claim 1  comprising measuring and/or monitoring the concentration of tracer in the samples. 
     
     
         18 . The method according to  claim 1  comprising calculating at least one flow characteristic for the at least one fracture based on the arrival time of tracer in the samples. 
     
     
         19 . The method according to  claim 1  comprising calculating at least one flow characteristic by quantifying a proportion of flow from each fracture stage by performing a dilution calculation. 
     
     
         20 . The method according to  claim 1  comprising measuring surface flow rate, measuring surface pressure, measuring downhole pressure, measuring pressure at a stage hydraulic fracture, calculating downhole pressure for each stage fracture and/or measuring pressure at each stage hydraulic fracture while producing from one or more wells and using these data as input for permeability and conductivity calculations. 
     
     
         21 . The method according to  claim 1  comprising determining an effect of a frac hit on production in a production well. 
     
     
         22 . The method according to  claim 1  analysing tracer data set for each tracer for each fracture stage. 
     
     
         23 . The method according to  claim 1  comprising calculating a residence time distribution data set for each tracer from each fracture. 
     
     
         24 . A method of collecting samples for analysis in characterising at least one fracture in a well system, wherein the system comprises a well combination comprising a first well and at least one second well and at least one fracture between the first well and the at least one second well; wherein the at least one fracture comprises a first tracer injected into the at least one fracture and a second tracer is located in or at the at least one fracture;
 the method comprising flowing fluid from the at least one fracture to the at least one second well to carry tracer to the at least one second well; 
 collecting samples from at least the second well. 
 
     
     
         25 . The method according to  claim 24  comprising producing fluid from or in the at least a second well to draw, pull and/or direct tracer and fluid in or through the at least one fracture into the at least second well. 
     
     
         26 . An interpretation method for characterising at least one fracture in well system, the method comprising:
 providing tracer data, the tracer data previously obtained by analysis of samples of fluid collected from a production well in a well system comprising a first well and at least a second well, and having at least a first fracture stage from the first well; wherein the at least first fracture comprises at least a first tracer injected into the fracture and at least a second tracer located in or at the fracture; wherein fluid is transferred from the at least one fracture to the at least one production well to carry tracer to the at least one production well;   calculating at least one flow characteristic from the tracer data.   
     
     
         27 . The method according to  claim 26  wherein fluid is drawn and/or pulled from or through the at least one fracture into the production well.