Presentation 4 mudlogging

OPERATIONS GEOLOGY
PRESENTATIONS
Presentation 4:
Basic Mudlogging
14 October 2016Ali Trichelli

Legend
 Introduction
 Inside the Mudlogging Unit
 Main Mudlogging Services
 Major Responsibilities of the Mudloggers
 Lag Time Determination
 Typical Monitored Parameters
 Standard Mudlogging Sensors
 The Gas System
 Real Time Data Display & Transmission
 Deliverables of the Mudlogging Contractor
 Issues with Mudlogging

Introduction
 Mud logging is a standard practice during drilling operations and is important for documenting the geology of a
well.
 Drilling mud and drill bit cuttings from the formation are evaluated and their properties recorded on a mudlog as a
visual analytical tool. Preserving and storing the rock cuttings and mud samples is normal procedure.
 From the cuttings, an oil stain or odor may be detected and becomes an excellent qualitative indicator.
 Continuous record of drilling parameters (penetration rate ROP, weight on bit WOB, rotation per minute RPM,
torque, etc…) and hydrocarbon shows is also provided.

Major Responsibilities of the Mudlogging Contractor
 Data Collection: recording the geological (cutting samples examination, lithological description & hydrocarbon shows
evaluation) and engineering data (Lag time, depth & ROP, WOB, RPM, etc…) obtained while drilling
 Data Evaluation: interpretation of the acquired data
 Communication: informing the client in a timely manner of significant changes in the well, by means of immediate
verbal communication and by standard written reports

Typical Drilling Parameters Monitored by the Mudlogging Contractor

Standard Mudlogging Sensors
Drawwork Sensor:
Bit position, depth ROP
Hook Position Sensor:
Bit position, depth ROP
Pump Stroke Sensor:
Pump strokes, RPM, cement pump
Hook Load Sensor:
WHO, WOB
Rotary Torque Sensor
Pressure Sensor:
SPP, Cement unit & casing pressures
Gas Sensor:
Explosive gas detection
Pit Level Sensors:
Pit volumes Density Sensor

The Gas System
TG & Gas
Chromatograph
Gas Trap
Hydrogen Generator
Gas Trap: a metal box
immersed in the shale shaker
possum belly, preferably in a
location of maximum mudflow
rate
The sample gas is introduced into a hydrogen flame. Any
hydrocarbons in the sample will produce ions when they are
burnt and will be recorded by the TG & gas chromatograph

Real Time Data Display & Transmission

Deliverables of the Mudlogging Contractor
 Mudlogs, gas logs, drilling logs, pressure logs
 Reports (daily, weekly, final)
Gas Log Pressure Log Mud Log

Issues
 The depth that the rock cuttings originated from is not always 100% accurate. Calculations can be made that
determine the time it takes for the drill cutting to reach the surface, this is called “lag time”. Some assumption have
to be made in the calculations because not all rock cuttings are the same size and density and the hole may not be
gauged so there can be some error in calculating the depth that the cuttings originated from.
 A small degree of mixing occurs in the mud before it reaches the surface, so the rock cuttings in a particular sample
may a mixture of cuttings from a range of depths.
 Contamination can sometimes be a problem when making interpretations of samples. There can be metal
contaminates in the drilling mud from fragments of the drill bit or drill string. Cement from well casings may get
into the drilling mud. Sometimes different materials may be mixed into the drill mud to help loss of circulation and
these can sometimes be misinterpreted as mica flakes, calcium carbonate, or various other minerals.

Next Presentation
 Drilling Mud
 Drilling Mud Circulating System
 Drilling Mud Types
 Drilling Mud Functions
 Drilling Mud Properties & Additives
 Drilling Mud Tests

Presentation 4 mudlogging

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