Proceedings Volume Cover
SOCIETY OF PETROLEUM ENGINEERS OF AIME  
6200 North Central Expressway  
Dallas, Texas 75206  
SPE 3155  
THIS IS  
A
PREPRINT  
-
SUBJECT TO CORR:&:TION  
Application of Minimum Cost Drilling Programs  
By  
Frank W. Cole, Member AIME, Frank W. Cole Engineering  
©
Copyright 1970  
American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc.  
This paper was prepared for the Central Plains Regional Meeting of the Society of Petroleum  
Engineers of AIME, to be held in Amarillo, Tex., Nov. 15-17, 1970. 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 else•  
where after publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF PETROLEUM ENGINEERS  
JOURNAL is usually granted upon 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 office. 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.  
ABSTRACT  
use today are more complex than they need to  
be. relatively simple program should be used  
initially; then, as more experience is gained,  
the programs can be made more complex.  
A
Minimum cost drilling programs have been  
available for about 10 years, but only recently  
have they been utilized to any extent. One of  
the principal disadvantages of most programs is  
that they assume rig operating costs are  
independent of bit weights and rotary speeds.  
Although the use of minimum cost drilling  
programs is relatively new, their proper use  
can effect substantial savings in the drilling  
operation.  
INTRODUCTION  
Since the late 1950's, as evidenced by the  
published petroleum literature, there has been  
a
strong interest in developing mathematical  
relationships which would describe and, there•  
fore, permit some type of optimization of the  
drilling operation. Beilstein and Cannonl made  
an important contribution to understanding the  
interrelationships of some of the more  
The principal uses of  
drilling program are in (1) planning the  
entire well, (2) selecting the proper bit,  
(3) optimum time to pull bit, (4) proper  
weight and speed to meet special conditions,  
such as extending bit life in order to save a  
round trip, reducing bit life as result of  
a minimum cost  
important variables affecting the economics of  
drilling. Speer2 later published valuable data  
which largely supported the observations of  
a
Beilstein and Cannon. Within  
a short period of  
a
time a number of analytical methods for  
changing formations, critical rotary speeds  
and crooked hole conditions, (5) revising  
optimum bit weights, rotary speeds, and bit  
footages on an instantaneous basis during  
drilling and (6) studying special problems  
such as the influence of rig costs on optimum  
drilling conditions.  
describing the drilling operation were pub•  
lished.3-7 All of these methods were developed  
primarily to study the effects of varying bit  
weights and rotary speeds on penetration rates  
and drilling costs. These analytical methods  
are now commonly referred to as minimum cost  
drilling or optimized drilling methods.  
A true  
minimum cost drilling program must include all  
variables influencing the drilling operation.  
Some of the most important of these variables  
are (1) drilling rig, (2) crew efficiency,  
(3) hydraulics programs, (4) type of mud, (5)  
bit selection, (6) bit weight and (7) rotary  
speed. There are numerous other factors which  
Minimum cost drilling programs can be  
economically used with  
a time-share computer  
and a teletype terminal. The terminal can be  
located at the rig or in the office.  
Most minimum cost drilling programs in  
References and illustrations at end of paper.