Proceedings Volume Cover
6200 North Central Expressway  
Dallas, Texas 75206  
NUMBER 3744  
Mud programs and drilling problems pertaining to  
the tertiary Clays and Shales, Norwegian Northsea  
I. Siem, Amoco Norway Oil Company,  
Oslo, Norway  
Copyright 1972  
American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc.  
This paper was prepared for the SPE-European Spring Meeting 1972 of the Society of Petroleum  
Engineers of AIME, held in Amsterdam, The Netherlands, May 16-18, 1972. Permission to copy is  
restricted to an abstract of not more than 300 words. Illustrations may not be copied. The abstract  
should contain conspicuous acknowledgment of where and by whom the paper is presented. Publication  
elsewhere after publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF  
PETROLEUM ENGINEERS JOURNAL is usually granted upo:n request to the Editor of the appropriate  
'journal provided agreement to give proper credit is made.  
Discussion of this paper is invited. Three copies of any discussion should be sent to the  
Society of Petroleum Engineers, P.O.Box 228, The Hague, The Netherlands. Such discussion may be  
presented at the above meeting and, with the paper, may be considered for publication in one of the  
two SPE magazines.  
and has  
high montmorillonite content.  
Problems encountered in drilling  
salt solution base mud is dis•  
Tertiary clays and shales in the  
southern part of the Norwegian  
Continental Shelf and the mud system  
cussed as an alternative to the commonly  
used lignosulfonate system. Hydration  
tests of formation samples in various  
most frequently used in this area, are salt solutions indicate that low density  
reviewed in this paper.  
solid content in the drilling fluid  
might be controlled more economically  
Severe viscosity problems frequently  
arise while drilling the top 10,000 feet  
of hole, which predominantly consists  
of clays and shales, and are the direct  
cause of several problems like swabbing  
formation; blocking of flowlines and  
shaker screens by very soft sticky clay;  
sticking of drill pipe; and bit and  
collar balling.  
by the use of a salt water base mud and  
centrifuges and fine screen shakers.  
To date mud properties have  
been controlled in the unsatisfactory  
manner of discarding old mud and making  
up new mud.  
It is concluded that  
25% on the cost of barite alone seems  
possible with salt solution base mud.  
a saving of  
The viscosity problems are the  
result of lack of solids removal  
equipment, the dispersing type drilling  
fluid used which makes the solid  
More important however, are the  
potentials for reducing rig time and  
consequently cost.  
separation more difficult, and  
that the lower 5,000 feet of formation  
is overpressured, behaves plastically,  
This study presents mud programs  
and drilling problems pertaining to the  
Tertiary clays and shales in the  
southern part of the-Norwegian  
References and illustrations at end  
of paper.  
Continental Shelf (see Fig. I).