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Evaluating Tight Gas, Shale Gas and Coal Bed Methane Wells using Mudlogging Methods By William S. Donovan, PE Donovan Brothers Incorporated Automated Mudlogging.

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Presentation on theme: "Evaluating Tight Gas, Shale Gas and Coal Bed Methane Wells using Mudlogging Methods By William S. Donovan, PE Donovan Brothers Incorporated Automated Mudlogging."— Presentation transcript:

1 Evaluating Tight Gas, Shale Gas and Coal Bed Methane Wells using Mudlogging Methods By William S. Donovan, PE Donovan Brothers Incorporated Automated Mudlogging Systems Our Corporate Motto WE DONT PASS GAS

2 07/25/06© Automated Mudlogging Systems SM Slide 2 of 33 Evaluating Tight Gas, Shale Gas and Coal Bed Methane using Mudlogging Methods Present an overview of presentation options

3 07/25/06© Automated Mudlogging Systems SM Slide 3 of 33 Evaluating Tight Gas, Shale Gas and Coal Bed Methane using Mudlogging Methods

4 07/25/06© Automated Mudlogging Systems SM Slide 4 of 33 Evaluating Tight Gas, Shale Gas and Coal Bed Methane using Mudlogging Methods

5 07/25/06© Automated Mudlogging Systems SM Slide 5 of 33 Evaluating Tight Gas, Shale Gas and Coal Bed Methane using Mudlogging Methods Present an overview of presentation options Define mudlogging gas measurements Explain why mudlogging is an effective tool Relate mudlogging shows to formation gas Discuss presentation options in detail Present an overview of presentation options Define mudlogging gas measurements Explain why mudlogging is an effective tool Relate mudlogging shows to formation gas Discuss presentation options in detail

6 07/25/06© Automated Mudlogging Systems SM Slide 6 of 33 Evaluating Tight Gas, Shale Gas and Coal Bed Methane using Mudlogging Methods MUDLOGGING GAS MEASUREMENTS DEFINTION EQUIVALENT METHANE IN AIR (% EMA) is a measure of methane in air at the measurement point expressed as a percent of methane in the sample or expressed differently 10,000 parts per million methane by volume. Other hydrocarbon gases are presented as if they were methane MUDLOGGING GAS MEASUREMENTS DEFINTION EQUIVALENT METHANE IN AIR (% EMA) is a measure of methane in air at the measurement point expressed as a percent of methane in the sample or expressed differently 10,000 parts per million methane by volume. Other hydrocarbon gases are presented as if they were methane

7 07/25/06© Automated Mudlogging Systems SM Slide 7 of 33 Evaluating Tight Gas, Shale Gas and Coal Bed Methane using Mudlogging Methods MUDLOGGING GAS MEASUREMENT DEFINITION A UNIT is a measure of hydrocarbon gases in air at the measurement point expressed as a fraction of samples total volume; typically, but not always, it is 0.01% of the total volume or expressed differently 100 parts per million gas by volume. Typically methane is the calibrating gas. MUDLOGGING GAS MEASUREMENT DEFINITION A UNIT is a measure of hydrocarbon gases in air at the measurement point expressed as a fraction of samples total volume; typically, but not always, it is 0.01% of the total volume or expressed differently 100 parts per million gas by volume. Typically methane is the calibrating gas.

8 07/25/06© Automated Mudlogging Systems SM Slide 8 of 33 Evaluating Tight Gas, Shale Gas and Coal Bed Methane using Mudlogging Methods MUDLOGGING GAS MEASUREMENT DISCUSSION Measured at the mudlogging unit Measured as methane Subject to calibration errors Not a direct measure of formation gas The definition of a UNIT has changed MUDLOGGING GAS MEASUREMENT DISCUSSION Measured at the mudlogging unit Measured as methane Subject to calibration errors Not a direct measure of formation gas The definition of a UNIT has changed

9 07/25/06© Automated Mudlogging Systems SM Slide 9 of 33 Evaluating Tight Gas, Shale Gas and Coal Bed Methane using Mudlogging Methods MUDLOGGING IS EFFECTIVE BECAUSE: Gas is measured directly at the surface Gas is insoluble in water Gas expands as it travels to the surface

10 07/25/06© Automated Mudlogging Systems SM Slide 10 of 33 Evaluating Tight Gas, Shale Gas and Coal Bed Methane using Mudlogging Methods MUDLOGGING IS EFFECTIVE BECAUSE: Gas is measured directly at the surface Gas is insoluble in water and drilling mud Gas expands as it travels to the surface

11 07/25/06© Automated Mudlogging Systems SM Slide 11 of 33 Evaluating Tight Gas, Shale Gas and Coal Bed Methane using Mudlogging Methods MUDLOGGING IS EFFECTIVE BECAUSE: Gas is measured directly at the surface Gas is insoluble in water and drilling mud Gas expands as it travels to the surface

12 07/25/06© Automated Mudlogging Systems SM Slide 12 of 33 Evaluating Tight Gas, Shale Gas and Coal Bed Methane using Mudlogging Methods MUDLOGGING IS EFFECTIVE BECAUSE: Gas is measured directly at the surface Gas is insoluble in water Gas expands as it travels to the surface

13 07/25/06© Automated Mudlogging Systems SM Slide 13 of 33 Evaluating Tight Gas, Shale Gas and Coal Bed Methane using Mudlogging Methods MUDLOGGING IS EFFECTIVE BECAUSE: Gas is measured directly at the surface Gas is insoluble in water Gas expands as it travels to the surface

14 07/25/06© Automated Mudlogging Systems SM Slide 14 of 33 Evaluating Tight Gas, Shale Gas and Coal Bed Methane using Mudlogging Methods The next six slide present the amount of gas liberated and brought to the surface for coal, shale, oil and gas reservoirs. The red and blue colored bars to the left show gas (red) and water (blue) values relative to the reservoirs. All slides have the same format, but different vertical scales Again the conclusion reached is that both conventional and unconventional hydrocarbon reservoirs liberate gas in quantities significantly higher than reservoirs containing water

15 07/25/06© Automated Mudlogging Systems SM Slide 15 of 33 Evaluating Tight Gas, Shale Gas and Coal Bed Methane using Mudlogging Methods

16 07/25/06© Automated Mudlogging Systems SM Slide 16 of 33 Evaluating Tight Gas, Shale Gas and Coal Bed Methane using Mudlogging Methods

17 07/25/06© Automated Mudlogging Systems SM Slide 17 of 33 Evaluating Tight Gas, Shale Gas and Coal Bed Methane using Mudlogging Methods

18 07/25/06© Automated Mudlogging Systems SM Slide 18 of 33 Evaluating Tight Gas, Shale Gas and Coal Bed Methane using Mudlogging Methods

19 07/25/06© Automated Mudlogging Systems SM Slide 19 of 33 Evaluating Tight Gas, Shale Gas and Coal Bed Methane using Mudlogging Methods

20 07/25/06© Automated Mudlogging Systems SM Slide 20 of 33 Evaluating Tight Gas, Shale Gas and Coal Bed Methane using Mudlogging Methods

21 07/25/06© Automated Mudlogging Systems SM Slide 21 of 33 Evaluating Tight Gas, Shale Gas and Coal Bed Methane using Mudlogging Methods Four methods can be used to relate mudlogging shows measured in EMA or Units to SCF gas volumes: 1.Carbide lags or gas referencing (Amen) 2.Deterministic modeling 3.Normalizing using open hole logging 4.Normalizing using core data All these methods can be used in concert. Carbide lag is my preferred method and is how the examples in this presentation were derived. Four methods can be used to relate mudlogging shows measured in EMA or Units to SCF gas volumes: 1.Carbide lags or gas referencing (Amen) 2.Deterministic modeling 3.Normalizing using open hole logging 4.Normalizing using core data All these methods can be used in concert. Carbide lag is my preferred method and is how the examples in this presentation were derived.

22 07/25/06© Automated Mudlogging Systems SM Slide 22 of 33 Evaluating Tight Gas, Shale Gas and Coal Bed Methane using Mudlogging Methods Carbide lagging is an established mudlogging tool Calcium Carbide reacts with water to make acetylene gas CaC 2 + H 2 0 = C 2 H 2 +CaO The relationship between acetylene and methane is established for the mudlogging unit before logging A measured amount of Carbide (acetylene) is put in the drill string during connections and pumped to the surface The peak gas value, the lag time, the gas reading before the peak and other data is recorded by the mudlogger Using the above data a gas show in EMA or units can be converted to SCF of gas liberated while drilling SCF/bulk volume (ft 3 ) can be calculated if hole volume is calculated. If density is known SCF/T can be calculated

23 07/25/06© Automated Mudlogging Systems SM Slide 23 of 33 Evaluating Tight Gas, Shale Gas and Coal Bed Methane using Mudlogging Methods The deterministic model gives insight into the mudlogging process Factors affecting mudlog gas shows will be presented starting from the formation being drilled to the mudlogging unit These factors are: 1) gas in the formation; 2) hole size; 3) drilling rate; 4) mud pump rate; 5) gas expansion and 6) gas trap efficiency Some factors such as flushing, flow line losses, gas trap instability and drilling mud interactions cannot be quantified by deterministic modeling The deterministic model gives insight into the mudlogging process Factors affecting mudlog gas shows will be presented starting from the formation being drilled to the mudlogging unit These factors are: 1) gas in the formation; 2) hole size; 3) drilling rate; 4) mud pump rate; 5) gas expansion and 6) gas trap efficiency Some factors such as flushing, flow line losses, gas trap instability and drilling mud interactions cannot be quantified by deterministic modeling

24 07/25/06© Automated Mudlogging Systems SM Slide 24 of 33 Evaluating Tight Gas, Shale Gas and Coal Bed Methane using Mudlogging Methods If all other factors are equal, doubling the gas in the formation doubles the gas show

25 07/25/06© Automated Mudlogging Systems SM Slide 25 of 33 Evaluating Tight Gas, Shale Gas and Coal Bed Methane using Mudlogging Methods If all other factors are equal, doubling the hole diameter, quadruples the gas show

26 07/25/06© Automated Mudlogging Systems SM Slide 26 of 33 Evaluating Tight Gas, Shale Gas and Coal Bed Methane using Mudlogging Methods If all other factors are equal, doubling the drilling rate, doubles the gas show

27 07/25/06© Automated Mudlogging Systems SM Slide 27 of 33 Evaluating Tight Gas, Shale Gas and Coal Bed Methane using Mudlogging Methods If all other factors are equal, doubling mud pump rate, decreased by one half the gas show

28 07/25/06© Automated Mudlogging Systems SM Slide 28 of 33 Evaluating Tight Gas, Shale Gas and Coal Bed Methane using Mudlogging Methods If all other factors are equal, doubling the depth of the formation doubles the gas show with some limitations The formula displayed is the basis for calculating Bulk Volume Mudlog Gas (BV mlg ) If all other factors are equal, doubling the depth of the formation doubles the gas show with some limitations The formula displayed is the basis for calculating Bulk Volume Mudlog Gas (BV mlg )

29 07/25/06© Automated Mudlogging Systems SM Slide 29 of 33 Evaluating Tight Gas, Shale Gas and Coal Bed Methane using Mudlogging Methods Gas trap efficiency and measurement stability is the largest cause of error in these calculations

30 07/25/06© Automated Mudlogging Systems SM Slide 30 of 33 Evaluating Tight Gas, Shale Gas and Coal Bed Methane using Mudlogging Methods

31 07/25/06© Automated Mudlogging Systems SM Slide 31 of 33 Evaluating Tight Gas, Shale Gas and Coal Bed Methane using Mudlogging Methods

32 07/25/06© Automated Mudlogging Systems SM Slide 32 of 33 Evaluating Tight Gas, Shale Gas and Coal Bed Methane using Mudlogging Methods

33 07/25/06© Automated Mudlogging Systems SM Slide 33 of 33 Evaluating Tight Gas, Shale Gas and Coal Bed Methane using Mudlogging Methods CONCLUSIONS Mudlogging is an effective evaluation tool If you have questions or comments contact me Bill Donovan (303) CONCLUSIONS Mudlogging is an effective evaluation tool If you have questions or comments contact me Bill Donovan (303)


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