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Hematite in mud
11 June 2018
Ladies and Gentlemen,

This is an old question, but I seem to have misplaced my old notes on the topic.

What are the views of the MWD engineers among us on the addition of Hematite in the mud as a weighting agent.
5 answer(s)
JaapvdS
Head of Well Engineering
State Supervision of Mines
Total Posts: 13
Join Date: 09/11/15

Hematite is a good weighting agent when heavy muds are required. There is a limit to the weight that can be obtained with barite, and using barite to the 'max' leaves you with a very viscous mud system.

Disadvantage of hematite is its hardness, so you will encounter higher wear on DP and casing, coupled with higher torque. For longer stretches use rotating wear reduction devices. These in turn will have an effect on circulating pressure. No such thing as a free lunch...

rollintr1
Drilling & Completions Advisor
SPREADAssociates
Total Posts: 5
Join Date: 17/05/15
I must take some exception to this - as long as the hematite is free of magnetite there is nothing in pure FeO2 that can cause magnetic interference. Hematite and other iron compounds have been used successfully in both water-base & non aqueous fluids widely with no problems. The use of low quality hematite especially in the Middle East gave the entire product line a black eye. As the quality of barite world wide continues to fall - there will be a need to use alternative weight materials in the future.
nbergstrom
Wellbore Positioning Advisor
Magvar
Total Posts: 32
Join Date: 03/07/08
I would be cautious about using any iron-bearing mineral in the mud.  This can be a cause of "magnetic mud" which tends to shield the MWD magnetometers in the cross-axial direction.  The effect is to reduce the measured magnetic field in the cross-axial direction, leading to directional errors.  A reduction of 1 or 2% can cause a significant azimuth error. 

Typically the magnetic mud problem is encountered when drilling with oil-based mud that is used for a long time.  Wear between casing and drill pipe causes microscopic iron particles suspended in the mud.  A ditch magnet helps but is not very efficient at removing these small particles. 
 
The effect is greatest when the mud around the MWD is stationary (pumps off).  If there is a difference in pumps on and pumps off cross-axial magnetic surveys, this can be suspected as a problem. Another diagnostic is to pump a pill of fresh OBM around the MWD to see if that makes a difference. 

For more info see Tim Allen's presentation at www.iscwsa.net > presentations > ISCWSA meeting 33 presentation #16. 
 
Steve Grindrod's presentation #07 at ISCWSA meeting 41 has some additional info and references to SPE papers, as does Giorgio Pattarini's presentation #07 at ISCWSA meeting 44. 

DMEkas
Drlg Fluids Supv
SPREADAssociates
Total Posts: 7
Join Date: 26/03/10
If your question is more general than MWD interference usage depends on many factors.
WBM vs NAF
O:W ratio
Solids removal equipment
Hole size
Flow rate
Hole angle
etc.
and the all important, mud weight required.
Personally have run 19.5+ ppg NAF using only barite without problems, but it was 98:2 O:W ratio.
Supposed to be more abrasive, but I do not have first hand knowledge of this.
rollintr1
Drilling & Completions Advisor
SPREADAssociates
Total Posts: 5
Join Date: 17/05/15
As long as the hematite has less than 1% magnetite concentration there should be no effect on the MWD
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