Mudlogging-Operations -Full presentation.ppt

Mudlogging Services
Mohamed Bekhit
14 February 2010

© 2007 Weatherford. All rights reserved.
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Mud Logging: An Overview

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What Is Mud Logging?
• Mud logging is the process of continuously collecting,
recording and analyzing the meaningful solids, fluids,
and gasses brought to the surface by mud.
• Provide comprehensive drilling data parameter
recording, monitoring and analysis.
• Real-time information service….

3
Mudlogging Operations – Drilling Crew
• Rig superintendent (Day toolpusher)
• Night toolpusher
• Drillers
• Assistant drillers
• Derrickman
• Roughnecks
• Roustabouts / load handling crew
• Mechanics and Electricians
• Catering / living quarters crew

4
Mudlogging Operations – Connection
• Adding fresh length (joint
or stand) of pipe so that
the bit can drill deeper.
• While connection check
the pit system level and
check gas trap level and
shakers.

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Mudlogging Operations – Connection

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• Withdrawing the drillstring is
known as (tripping out) and the
whole operation of extraction
and re-insertion (tripping in) of
the drillstring is a round trip.
• POOH (pull out of hole) is
another expression for tripping
out.
• RIH (run in hole) is another
expression for tripping in
Mudlogging Operations – Tripping

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Mudlogging Operations – POOH

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Mudlogging Operations – RIH

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Mudlogging Operations
Back-reaming
• Continuous rotation of the Drillstring as it is being
pulled out of the hole in order to keep the hole clean
and maintain the wellbore in gauge
Wiper Trip
• To prevent cuttings build up, esp. in deviated wells
• POOH to last casing shoe or to pull out a few stands
(10-30 stands)

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1. Suction Pit
2. Mud Pump
3. Standpipe
4. Swivel
5. Kelly
6. Drillstring and Bit
7. Annulus
8. Return Flowline /
Shakers
9. Suction Pit
Drilling Fluid Circulating System

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Circulating System – Shale Shaker
Shale shaker
Flowline
Possum belly

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Lag Time Determination
• What is Lag Time
• What are the factors affecting Lag Time
• How is Lag Time measured
• How is Lag Time checked

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• Lag time is the definite time interval required for
pumping drilled cuttings from a particular depth to the
surface where they can be collected
Lag Time Definition
• Always exists
• Changes continuously as the hole deepens
• Must be frequently checked and corrected

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Lag Time
Factors Affecting Lag Time
• Volume of the mud in the Annulus
• Mud flow rate
Annulus
• It is the space around a pipe in the wellbore, the outer
wall being the wall of either the hole or casing
• Sometimes called annular space

15
Volume of Mud in the Hole
• As hole gets deeper, mud volume increases,
therefore, lag time increases
• As the annular diameter gets larger due to hole
washouts the mud volume increases, the lag time
increases
Mud Flow Rate
• The faster the mud is pumped the quicker it returns to
the surface and hence the lag time is reduced
Lag Time

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Lag Time Measured Using Velocity Method
Annular velocity ann. sec (ft/min) = 24.51 x Q / (D2 – d2)
Where,
Q = flow rate (gpm), D = hole or casing ID (ins.), d =
DP/DC OD (ins.)
Lag time ann. sec (mins) = Length of annular section / Annular
velocity of annular section
Lag time (mins) =  Lag time ann. sec
Lag time (strokes) = Lag time (mins) x spm

17
Lag Time Measured Using Volume Method
Annular volume = (D2 – d2) x 0.000971 x Length of annular
section
or
Annular volume = ((D2 – d2) / 1029.4) x Length of annular
section
Lag time ann. sec (mins) = Annular volume (bbls) / flow rate
(bbls/min)
Lag time (mins) =  Lag time ann. sec
• Disadvantage: affected by flow rate changes

18
Lag Time Measured Using Volume Method
Annular volume = (D2 – d2) x 0.000971 x Length of annular
section or
Annular volume = ((D2 – d2) / 1029.4) x Length of annular
section
Pump Output (bbls/stroke) = Pump output (gpm) / (spm x
42)
Lag time ann. sec (strokes) = Annular volume (bbls) / Pump
Output (bbls/stroke)
• Advantage: not affected by changes in flow rate

19
Well Profile
• Depth: 7750 ft
• Hole size: 8.5”
• Pump Output: 425 gpm at 100 spm
• Casing:
– shoe at 6000 ft
– 9 5/8” OD; 9” ID
• DP:
– 6350 ft.
– 5” OD; 4.276” ID
• DC:
– 1400 ft.
– 7” OD; 3.5” ID

20
Example #1 (Velocity Method)
Section 1: 24.51 x 425 / (92 - 52)
Annular Velocity = 186 ft/min
Annular Section = 6000 feet
Lag Time for Section = 32.26 minutes
Section 2: 24.51 x 425 / (8.52 - 52)
Annular Velocity = 220.46 ft/min

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Example #1 (Velocity Method)
Section 3: 24.51 x 425 / (8.52 - 72)
Annular Velocity = 448 ft/min
Total Lag Time = 32.26 + 1.59 + 3.13 = 36.98 minutes

22
Example #2 (Volume Method)
Section 1: (92 - 52) x 0.000971 x 6000
Annular volume = 326.25 bbls
Section 2: (8.52 - 52 ) x 0.000971 x 350
Section 3: (8.52 - 72 ) x 0.000971 x 1400

23
Example #2 (Volume Method)
Pump output (bbls/min) = 425 gpm/42 = 10.12 bbls/min
Pumps are pumping at 100 spm -> Pump output
(bbls/stroke)= 10.12/100 = 0.1012 bbls/stroke
Total Lag Time (strokes)
= (326.25 + 16.05 + 31.6) / 0.1012
= 374.15 / 0.1012 = 3697 strokes

24
Lag Time Check
• Under normal circumstances a check should be made
every twenty-four hours or 400 ft, whichever comes
first. However, if carbide information is required due to
suspicions of incorrect lag or washout, then carbides
should be run as required
• A tracer is used to obtain an “accurate” measurement of
lag time
• Common tracers used are:
– Calcium carbide (most common)
– Rice, lentil, cellophane
• Carbide + water -> acetylene

25
Example
• Example:
– Actual strokes from carbide = 5128 strokes
• Calculations:
– Down strokes are 1278 strokes.
– Lag strokes are 3697 strokes
– Pump output is 0.1012 bbls/stroke
• Calculate carbide check?

26
Collecting a Sample

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• Paleontological Analysis
• Geochemical Analysis
• Oil Company Partners
• Governmental Requirements
• Future Reference / Library Samples
Reasons For Sample Collection

28
Sample Intervals
• Set by the client
• Common intervals: 5 feet to 30 feet
• Regardless of the sampling interval, under no circumstances
should the Mudloggers neglect their other responsibilities
• Other times that the sample interval should be shortened:
– During coring – 1 ft or 0.5 meter intervals
– Areas of geological interest
– Changes in drilling parameters (drill breaks / reverse drill breaks,
torque changes)
– Changes in mud properties (viscosity, cut MW, chlorides, etc)
– Changes in gas content

29
Sample Types
• Unwashed Samples
• Washed and Dried Samples
• Geochemical Samples
• Paleontological Samples
• Metal Shavings
• Mud Samples

30
Sample Collection
• Install a sample collection board at the base of the shaker
• Try to collect from the shaker with the smallest mesh size
• Samples are taken at regular intervals specified by the
client
• Samples should be taken when changes in ROP,
background gas or any other parameter is noticed
• When sampling in smaller intervals than required, the
sample bags should be progressively filled up
• Clean the sample board after a sample is taken

31
Sample Catching Board

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Sample Preparation

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Cuttings Examination
• Samples are examined under the microscope for:
– Lithology
– Oil staining
– Porosity
• Objective:
– To depict changes of lithology and appearance of
new formations

34
Cuttings Examination
Sources of Sample Contamination
• Cavings
• Recycled Cuttings
• Mud Chemicals
• Cement
• Metal
• Unrepresentative Samples

35
Sample Description
• Allows others to understand the components and
structure of the rock and to draw conclusions as to the
source, depositional environment and subsequent
history of the formation
• Allows others to recognize the rock whenever it is
seen again
Major Functions of Sample Description

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• Porosity is a measure of the volume of void space in
the rock. It determines the amount of fluid that is
present in a rock.
• Permeability is a measure of the capacity of a rock
for transmitting fluid and it is dependent on effective
porosity and the mean size of the individual pore
spaces. It has a direct bearing on the amount of fluid
that can be recovered.
Porosity and Permeability

37
Sample Description Format
• Rock type / Classification
• Color
• Texture: Cuttings shape and parting (calcareous and
argillaceous lithologies), Grain size, Grain shape or
roundness, Sorting, Hardness or induration, Luster / Slaking /
Swelling
• Cementation or matrix
• Fossils and accessories
• Visual structures
• Visual porosity
• Oil show descriptions

38
Particle Shape: Roundness vs. Sphericity

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Sorting

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• Solid Hydrocarbons and Dead Oil
• Oil show description
• Hydrocarbon Odor
• Oil Staining
• Natural Fluorescence
• Solvent Cut Fluorescence
• Other Tests
Oil Show Evaluation

41
• Take a mud sample, aside from the regular sample
or bottoms up sample, when there are significant
gas shows. If a significant gas peak arrives in
between sampling intervals, a spot sample is
caught along with a mud sample.
• Pour mud sample into a shallow dish and observe
under UV light. If nothing is seen, water is added to
the mud and the mixture is stirred. Again the
sample is observed under UV light.
Sample Examination Procedure For HC Shows

42
• The unwashed sample is also observed under UV
light.
• For the lithological samples, smell the sample first
before observing it under the microscope. Observe
sample under microscope for staining / bleeding.
• Place some oil-stained cuttings, if any, into some of
the depressions on the spot plate. Observe under
microscope.

43
• Observe sample tray under UV light. Separate
some fluorescing grains and place them in the spot
plate.
• Observe the grains that have been selected in Step
6 under the microscope for stains/bleeding.
• Use the Solvent Cut Test on the samples in the
spot plate. Observe under UV light.
• Observe cutting samples in plain light.
• Observe the residue.

44
Observing a Sample Under the UV Box

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• Free oil in mud: amount, intensity and color
• Petroliferous odor: type and strength
• Visible oil staining/bleeding: distribution, intensity and
color
• Sample Fluorescence: percentage, intensity, color
• Solvent cut: speed, character, intensity and color
• Cut color and intensity
• Cut residue (intensity and color)
Order of Oil Show Description

46
Bleeding Core Sample

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Gravity (API) Color at 3600A
< 15 Brown
15 - 25 Orange
25 - 35 Yellow to Green
35 - 45 White
> 45 Blue White to Violet
Fluorescence: Indication of API Gravity

48
Rock Type Fluorescence Color
Dolomite, Sandy Limestone yellow, yellowish brown
Some Limestones (magnesian) brown
Chalk, chalky limestones purple
Paper Shale yellow to coffee brown, greyish
Fossils yellow-white to yellow-brown
Marl, Clay Marl yellowish to brownish grey
Anhydrite grey brown, greyish, blue
Mineral Fluorescence

49
• The speed in which the solvent cut occurs yields
useful info
• If the suspected cutting will not initially cut, the test
can be repeated. Samples can be dried, crushed or
have diluted HCl applied to it
• The residue oil that remains in the spot plate is the
oil’s natural color
• Be careful not to get the cutting agent into the rubber
of the dropper as it might “contaminate” the solvent by
giving it a pale yellowish fluorescence
Solvent Cut or “Wet Cut” Test

50
• Place a few drops of solvent, enough to immerse
the sample, on the sample in the depression in the
spot plate or the test tube.
• Observe the following:
– Cut speed
– Cut nature
– Cut color fluorescence and intensity
– Cut color intensity
– Residue color and intensity
How To Do A Solvent Cut Test

51
• Lack of visible stain is not conclusive proof of the
absence of hydrocarbons
• Lack of fluorescence is not conclusive proof of the
absence of hydrocarbons
• Hydrocarbon shows will usually give a positive cut
fluorescence (wet cut). High gravity hydrocarbons will
often give a positive cut fluorescence and/or a
residual cut, but will give negative results with all other
hydrocarbon detection methods. Minerals which
fluoresce will not yield a cut.
Summary

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• To collect and record all the engineering and
geological data obtained while drilling
• To interpret the acquired data
• To inform the client of significant changes in the well
• Maintain good relations with the client and other
personnel on the rig
• Ensure that the unit and equipment are properly
maintained and in good working order
• To perform all duties in a safe manner
Responsibilities of a Mud Logger

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