04_Mud Logging Theory, Lag Calculatios & Responsibility[1]

8/7/2019 04_Mud Logging Theory, Lag Calculatios & Responsibility[1]

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MUD LOGGING DEFINITION,THEORY & LAGCALCULATIONS


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- Mud logging is a service that qualitatively andquantitatively obtains data from, and makesobservations of, drilled rocks, drilling fluidsand drilling parameters in order to formulateand display concepts of the optional, in situcharacteristics of formations rocks with theprimary goal of delineating hydrocarbonshows worthy of testing.-

The mud logging unit is the information center on the rig site to serve both exploration anddrilling.


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Role played by Mud Logging Unitthe collection of the rock cuttings which isgeologically described, examined for anyoil shows and then packed.the hydrocarbon & some nonhydrocarbone gas monitoring while drilling.the monitoring of the drill fluid volume and

to immediately inform the personnel incharge about any change in that volumeconfirming with the driller about any drilling

breaks.


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.1the generation of mud logs and graphs

during the drilling of the well, acquisition of the data and producing a final well report..2the monitoring of the drilling parameters &

informing the personnel in charge aboutany anomalies..3monitoring the trips and updating a trip

sheet at a five -stand basis.4the detection and evaluation of the

formation pressure, the hydraulicsoptimization and the well control.


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The mud logging unit is consideredThe mud logging unit is consideredthe information centre of the rigthe information centre of the rig

site as the unit participates insite as the unit participates inthe monitoring of each andthe monitoring of each and

every rig operation.every rig operation.


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TYPES OF MUD LOGGING UNITSTYPES OF MUD LOGGING UNITSO ff - line mud logging units.O n - line mud logging units.

A- Mud Logging Off - line service featuresThe off line mud logging unit includes anumber of separate panels. Each panelworks independently and is responsible for measuring a definite parameter. There is nocommunication between these panels. Noautomatic calculations can be done and nodata storage. All panel calibrations are done

manually.


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TYPES OF MUD LOGGING UNITSTYPES OF MUD LOGGING UNITS

B- Mud Logging On - line service features1- Minimum human interference:- R andom errors minimized, i.e best accuracy.- More time for interpretation & More time for monitoring.2- Fully computerized service:

- High speed data processing (possible datatransmission)

- B etter presentation of data & O n time decisionmaking.


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B- Mud Logging On - line service

features (continue)3- Best possible equipment design:- Maximum possible accuracy.- Minimum systematic errors & Minimum downtime.4- Intrinsic safety:

- S afety environment- S afety equipment & Efficient warning system.


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DU TIES & R ESPO NSIBILI TIESMud Logging Unit Captain.

The U nit captain is the senior mud logging engineer onthe location. H e has primary responsibility for themaintenance, management and provision of service bythe logging unit, its equipment and personnel to theclient.

Mud Logger.H e is responsible for the maintenance and correctoperation of the equipment. H e is responsible for thecollation and presentation of the information monitoredin accordance with company standard procedures andcustomer requirements to ensure a high quality

service.


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The Mud Logging Theory & LagThe Mud Logging Theory & Lag

CalculationsCalculationsTheory:The mud logging theory is based on the mudcycle principal. The mud is sucked from the pits(Active P it) and pumped via the drilling stringdown to the hole bottom. The mud is thenbumped against gravity through the annulus upto the shakers. The time necessary to get thedrilled samples to the surface is exactly the timerequired to pump the mud volume through thispassage. This is calculated and is known as Lagtime or lag strokes


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LagLagLag Deinitions:Lag Deinitions:

Lag time is the time the mud takes to travelinside the hole between two specified depthpoints.The time taken between the surface to thebottom of the hole is called lag downor Lag in.

The time taken between the bottom of the holeto the surface is called lag -up or bottomsup.The surface to surface time is called C ompletecycle or In/O ut time.


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LagLagLag Equations:Lag Equations:

Converting Barrels Gallons:Gallons (gal) = Barrels 42

Converting Gallons Barrels:Barrels (bbl) = Gallons 42Calculating Pipe Volume:

Pipe. Volume (bbl)(Pipe / Collar ID

2Length(ft)

1029!

v)


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C . C alculating Annular volumeC . C alculating Annular volume

D . C alculating Lag in S trksD . C alculating Lag in S trks Ann. Volume (bbl)

(H ole / C asing ID2

P ip e / C ollar O D2

L ength(ft)

1029!

v)

L ag in strokes AnnularVolume bblP ump O u tput bbl s tk

!( )

( / )


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Lag EquationsLag EquationsCalculating lag in minutes:Calculating lag in minutes:

)(min

spm Rate Pump

strokesin Lag utesin Lag !


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Converting Meter Foot:Feet (ft) = Meter x 3.281

Converting Cu. in Barrels:Barrel (bbl) =9702 cu. inConverting g/cc ppg:ppg = g/cc x 8.33

Lag EquationsLag Equations


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Lag EquationsLag EquationsLag Correction:Lag Correction:

The number of strokes from the surface tothe bit inside the pipe.The total number of strokes from startingup the pump until the gas arrives at thesurface.S

ubtract 1 from 2The resulting number of strokes is the actuallag time. From this it is possible to estimatethe amount of washout in the hole.

04_Mud Logging Theory, Lag Calculatios & Responsibility[1]

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