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1. US20170321547 - Method and system for establishing well performance during plug mill-out or cleanout/workover operations

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Claims

1. A method for characterizing a hydraulically-fractured hydrocarbon-bearing formation that is traversed by a well having a plurality of intervals between a surface and bottom of the well, the method comprising:
analyzing flow characteristics of return fluid that flows from an interval of the plurality of intervals back to a surface-located facility during well operations; and
characterizing at least one local formation property of the hydraulically-fractured formation adjacent to the interval based on the flow characteristics.
2. The method according to claim 1, wherein:
each interval of the plurality of intervals is hydraulically isolated from every other interval of the plurality of intervals by corresponding plugs; and
the interval is a newly-opened well interval that is opened by plug mill-out operations.
3. The method according to claim 2, wherein:
the analyzing of the flow characteristics of the return fluid uses measurements of surface flow characteristics of the return fluid and the downhole pressure measurements to calculate and model return outflow from all open intervals, including the newly-opened interval.
4. The method according to claim 3, wherein:
the analyzing of the flow characteristics of the return fluid calculates the return outflow of the newly-opened interval by isolating the contribution of return outflow for the newly-opened interval from a previous model of return outflow for from all open intervals.
5. The method according to claim 4, wherein:
the contribution of return outflow for the newly-opened interval is derived from incremental changes to a model over successive plug mill-out operations and corresponding intervals.
6. The method according to claim 3, wherein:
the hydrostatic pressure of the milling fluid supplied to the downhole milling bit is greater than formation pressure, and the analyzing of the flow characteristics of the return fluid calculates the outflow of milling fluid into fractures of the newly-opened well interval.
7. The method according to claim 6, wherein:
the at least one local formation property is derived from the calculated outflow of milling fluid into fractures of the newly-opened well interval.
8. The method according to claim 6, wherein:
the milling fluid is water-based, and the analyzing of the flow characteristics of the return fluid analyzes flow characteristics of a water phase at the surface to calculate the outflow of milling fluid into fractures of the newly-opened well interval.
9. The method according to claim 6, wherein:
the milling fluid is oil-based, and the analyzing of the flow characteristics of the return fluid analyzes flow characteristics of an oil phase at the surface to calculate the outflow of milling fluid into fractures of the newly-opened well interval.
10. The method according to claim 3, wherein:
the hydrostatic pressure of the milling fluid supplied to the downhole milling bit is less than formation pressure, and the analyzing of the flow characteristics of the return fluid calculates the inflow of water, oil, gas and/or solids from the fracture and/or formation into the newly-opened interval based on the return outflow for the newly-opened interval.
11. The method according to claim 10, wherein:
the at least one local formation property is derived from the calculated inflow of water, oil, gas, solids, or a combination thereof from the fracture and/or formation into the newly-opened interval.
12. The method according to claim 10, wherein the analyzing of the flow characteristics of the return fluid analyzes flow characteristics of a plurality of different phases at the surface to calculate the inflow of water, oil, gas, solids, or a combination thereof from the fracture and/or formation into the newly-opened interval.
13. The method according to claim 1, wherein:
the interval is subject to a well cleanup or workover operation.
14. The method according to claim 1, wherein:
the at least one local formation property is selected from the group including
fracture area;
fracture conductivity;
fracture connectivity with wellbore;
fracture geometry; formation pressure; formation productivity;
whether or not the interval is in communication with the local region of the formation adjacent to the interval;
the number of fractures (or fracture clusters) in communication with the local region of the formation adjacent to the interval;
whether or not the fractures that were created by hydraulic fracturing of the formation adjacent to the interval provide fluid communication (such as behind-the-casing fluid communication) with the fractures adjacent to a neighboring interval;
whether or not the local region of the formation that is connected to the interval by fractures is normally-pressured, over-pressured or under-pressured (which is an indication of a depleted zone);
whether or not the local region of the formation that is connected to the interval by fractures is overbalanced or underbalanced with respect to the wellbore at the time of the mill-out operations;
whether or not the local region of the formation that is connected to the interval by fractures is prone to either proppant production, formation failure of both;
wettability and propensity to fluid leakoff and imbibition for the local region of the formation that is connected to the interval by fractures;
rock quality of the formation, such as porosity, hydrocarbon content, mineralogy, and formation toughness, lamination density, and density of natural/induced fractures; and
mechanical properties of the formation, such as stress, Young modulus, and Poison ratio.
15. The method according to claim 1, wherein:
the flow characteristics of the return fluid are derived from the output of a surface-located multiphase flow meter.
16. The method according to claim 1, wherein:
the return fluid includes milling fluid that is supplied to a downhole milling bit for milling out a plug.
17. The method according to claim 16, wherein:
hydrostatic pressure of the milling fluid supplied to the downhole milling bit is greater than formation pressure.
18. The method according to claim 17, wherein:
the analyzing of the flow characteristics of the return fluid accounts for an outflow of milling fluid into fractures of the newly-opened well interval.
19. The method according to claim 16, wherein:
hydrostatic pressure of the milling fluid supplied to the downhole milling bit is less than formation pressure.
20. The method according to claim 19, wherein:
the analyzing of the flow characteristics of the return fluid accounts for an inflow of fluid from fractures of the newly-opened well interval.
21. The method according to claim 1, wherein:
the inflow of fluid from fractures of the particular interval includes at least one of: water-based fluid, oil, gas and solids.
22. The method according to claim 1, wherein:
the analyzing of the flow characteristics of the return fluid is based on data gathered under steady-state conditions where there are no surface-controlled variations in well pressure.
23. The method according to claim 1, wherein:
the analyzing of the flow characteristics of the return fluid is based on data gathered under conditions where there are surface-controlled transient variations in well pressure.
24. The method according to claim 1, wherein:
a working fluid is supplied downhole during the well operations, wherein the working fluid incorporates at least one tracer compound to help quantitatively distinguish the working fluid from reservoir fluids.
25. The method according to claim 24, further comprising: using a surface-located chemical analyzer to measure concentration of the at least one tracer compound in return fluid that flows to the surface in order to discriminate between sources and sinks of the working fluid, reservoir fluids, or both during the well operations.
26. The method according to claim 24, further comprising: varying concentration of the tracer compound(s) in a controlled manner in conjunction with controlled pressure variations of the working fluid supplied downhole during the well operations in order to discriminate between sources and sinks of reservoir fluids during the well t operations.
27. The method according to claim 1, wherein:
at least one tracer compound is incorporated into fracturing fluid used to fracture the formation; and
a working fluid is supplied downhole during the well operations;
wherein the at least one tracer compound can help quantitatively distinguish the fracturing fluid from the working fluid, other reservoir fluids (such as connate water), or both.
28. The method according to claim 27, further comprising:
using a surface-located chemical analyzer to concentration of the at least one tracer compound in return fluid that flows to the surface in order to discriminate between sources and sinks of reservoir fluids during the well operations.
29. The method according to claim 1, further comprising:
tagging fluid elements of working fluid that is pumped downhole;
measuring one or more fluid properties of the respective fluid elements that are pumped downhole;
detecting respective tagged fluid elements as part of return fluid at the surface;
measuring one or more fluid properties of the respective fluid elements that are detected as part of return fluid at the surface; and
comparing the fluid properties of the tagged fluid elements from supply to return at the surface in order to characterize the injectivity or inflow from a particular well interval and to characterize the local formation properties of the particular well interval.
30. The method according to claim 29, wherein:
the measuring of the one or more fluid properties of the respective fluid elements that are pumped downhole involves a surface-located gas analysis system that extracts and quantitatively analyzes the concentration of hydrocarbon gas entrained in the respective fluid elements that are pumped downhole; and
the measuring of the one or more fluid properties of the respective fluid elements that are detected as part of return fluid at the surface involves uses a surface-located gas analysis system that extracts and quantitatively analyzes the concentration of hydrocarbon gas entrained in the respective fluid elements that are part of the return fluid at the surface.
31. A method for characterizing a hydraulically-fractured hydrocarbon-bearing formation that is traversed by a well having a plurality of intervals between a surface and a bottom of the well, the method comprising:
analyzing flow characteristics of return fluid that flows from one or more intervals of the plurality of intervals back to a surface-located facility during well operations; and
characterizing at least one property relating to solids production of the one or more intervals based on the flow characteristics.
32. The method according to claim 31, wherein:
the surface flow characteristics of the return fluid are measured by a surface-located multiphase flow meter.
33. The method according to claim 31, wherein:
each interval of the plurality of intervals are is hydraulically isolated from every other interval of the plurality of intervals by corresponding plugs; and
the one or more intervals are opened by plug mill-out operations.
34. The method according to claim 33, wherein:
the at least one property characterize solids production from fractures that are in fluid communication with a perforated zone of the formation.
35. The method according to claim 34, wherein:
the at least one property further characterizes a profile of solids production from fractures that are in fluid communication with a plurality of perforated zones of the formation.
36. The method according to claim 33, wherein:
the at least one property characterizes deposited solids in the one or more intervals.
37. The method according to claim 36, wherein:
the at least one property further characterizes a profile of deposited solids in the one or more intervals.