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PETE 411Well Drilling
Lesson 4
Drilling Cost & Drilling Rate
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Contents
The AFE
Drilling Cost and Bit Change
Factors Affecting Drilling RateBit Weight, Rotary Speed
Bottom-hole Cleaning
Md !roperties, Solids Content"ydrostatics
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HW #2. ADE 1.12, 1.13, 1.14 Due Friday, Sept. 13, 2002
Read: ADE, Ch. 1 (All)
Learn: Rig Compoet! " De#iitio!
Assignments
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e!ore getting a""roal to drill a $ell t%e
Drilling Engineer mst "re"are an A'E
( a detailed )ost estimate !or t%e $ell
DR# C$M!%ETED
"$%E
&'TA'(&B%E C$STS ) )
TA'(&B%E C$STS ) )
$%$A& C%S$ ' '
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A*TH+R-AT+ '+R E/PEDT*RE 0A'E
EE*D+$RE DR- %&E C%/&E$ED (24. DA-S) (32. DA-S)
+*$A*+&E C%S$S %$CAT&$' !RE!ARAT&$' *+,+++ ,+++
DR&%%&'( R&( A'D T$$%S ./0,10 *,1* DR&%%&'( F%2&DS 11*,3* 11,/4 RE'TA% E52&!ME'T 44,0/ 1**,40 CEME'T&'( 3/,* 3,*/
S2!!$RT SER6&CES 1.,.0 .4,30 TRA'S!$RTAT&$' 4+,.++ 0*,3++ S2!ER6&S&$' A'D ADM&'7 .*,.0. *+,4/1 S"$%$A& 14,2 1,125,1
$A*+&E C%S$S
T2B2%AR E52&!ME'T 3+,1+1 03,./ WE%% "EAD E52&!ME'T 1,03 1,.+1 C$M!%ET&$' E52&!ME'T + 1,414
S"$%$A& 422,5 1,01,446
S"$%$A& 1,236,3 2,14,02
7 C%*$+*E*C- (18 99) 1,423,66 2,455,62
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Drilling Cost s. Time
DE$#t
DA-S or D%&&ARS
TD
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Drilling Cost Analsis
$he Drillig Egieer:
Recommends drilling procedres that
8ill safely drill and complete the 8ellat the lo8est cost possi9le
Ma:es recommendations concerningroutie rig operatio!;
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T%e Drilling Engineer
E;ample!o# routie rig operatio!
drilling flid treatment
pmp operation
9it selection
handling pro9lems dring thedrilling process
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T%e Drilling Cost E3ation:
Cf= drilling cost, )
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Eam"le 1.5
A recommended 9it program is 9eing prepared fora ne8 8ell sing 9it performance records fromnear9y 8ells7
Drilling performance records for three 9its aresho8n for a thic: limestone formation at /,+++ ft7
Determine 8hich 9it gies the lo8est drilling cost ifthe operating cost of the rig is )3++
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Assme that each of the 9its 8as operated atnear the minimm cost per foot attaina9le forthat 9it7
Mean
Bit Rotating Connection !enetrationCost Time Time RateBit >)? >hors? >hors? >ft
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7oltion:
The cost per foot drilled for each 9it typecan 9e compted sing E7 1717 For Bit
A, the cost per foot is
071*
?417+0713>3++0++Cf =
+++=
ft
)
D
?ttt>CCC
tc9r9f
=
+++
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7oltion:
Similarly, for Bit B,
71.
?437+47-4>3++/++,3Cf =+++=
ft)
D?ttt>CCC
tc9r9f
= +++
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7oltion, )ont6d
Finally, for Bit C,
.71+
?4-7+07/->3++-++,3Cf =
+++=
ft)
D?ttt>CCC
tc9r9f
= +++
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7oltion, )ont6d
Bit A; )3701
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Drilling Costs
Tend to increase e;poetially 8ithdepth7 Ths, 8hen cre-fitting drilling
cost data, it is often conenient toassme a relationship 9et8een total8ell cost, C, and depth, D, gien 9y
C= ae8D 77>1714?
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Drilling Costs, )ont6d
Constants aand bdepend primarily on the8ell location7
Sho8n on the ne=t page is a least-sares
cre fit of the soth %oisiana completed8ell data gien in Ta9le 1747
Depth range of 4,++ ft to .1,+++ ft7
For these data,a @1 1+ dollars
b@. 1+-3 ft-17
C= aebD
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Fig. 1"5. &ea!t"!>uare ?ur@e #it o# 16 ?ompleted ell?o!t! #or ell! Belo 6,00 #t i the !outh &oui!iaa area.
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Penetration Rate
When maor ariations are not present inthe s9srface lithology, the penetrationratesally decreases e=ponentially 8ith
depth7 2nder these conditions, thepeetratio ratecan 9e related to depth,D, 9y
8here anda2
are constants7
)18.1,........(Kedt
d !303.2 2
=W"#?
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Drilling Time
The drilling time,td , reired to drill to agien depth can 9e o9tained 9y separating
aria9les and integrating7 Separatingaria9les gies
dDedtF Da*+*7.D
+
t
+
.d
=
$%te&'!ti%& !%d sol(i%& )o' tdyields
?1/7177777>?7777777771e>Fa*+*7.
1t Da*+*7.
.
d.
=
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Drilling Time )ont6d
lottig depth @!. drillig time #rom pa!tdrillig operatio!:
A. Allo8s more accrate prediction of time andcost for drilling a ne8 8ell
. &s sed in ealating ne8 drilling
procedres >designed to redce drillingtime to a gien depth?7
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E/A9PLE ( Cost "er !t
t R D $otal Co!t C# hr #ph #t ' '
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Cost "er !t !or one entire 8it rn
Minimum Cost
0
60
50
0
40
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E)onomi) Pro)edre in a8oe Ta8le
Can pll 9it after a9ot . hr7 >)3.7+
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E)onomi) Pro)edre in a8oe Ta8le
Also sed 8ith tngsten car9ide insert9its 8hen inserts are 9ro:en orplled ot of the matri=7
2nfortnately, 8ear rate 8ith insert9its is npredicta9le7
Economically, the insert 9it shold 9eplled 8hen the cost in )
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E)onomi) Pro)edre in Ta8le
Bits plled for economic reasons ma:eit hard to o9tain 8ear information7
$perator might pll 9it after 1.+ hrofse 9t part of 9it might get left in
hole7 Recoery is ery difficlt7 AoidG
4Hof roc: 9its are plled green or9efore the 9it is 8orn ot7
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An increase in
T$R52E mayindicate that a 9itshold 9e plled7
E=perience oftendictates 8hen to
pll 9it >footage orhors?7
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'a)tors t%at a!!e)t Penetration Rate
Type of Drill 9it
Bit 8eight
Rotary speed
Bottom-hole cleaning
Md properties
Roc: hardness
Formation pore pressre
6aria9les;
Fi=ed Factors;
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it 7ele)tion is 8ased on
!ast 9it records
(eologic predictions of lithology
Drilling costs in )
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it Weig%t and Rotar 7"eed
&ncreasing 9it 8eight and rotary speed9oosts drilling rate
These increases accelerate 9it 8ear
Field tests sho8 that drilling rateincreases more or less in directproportion to 9it 8eight
40 000 lB#
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Co!ider 10 hole
(dot o@erdo)
D r
i l l i g R
a t e
, # t < h
r
it eight ; 1,000 lB
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Dr
illi
g
Ra t
e ,
#t
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D r
i l l i g R
a t e , # t < h
r
EFFEC$ %F ACG RESSREGeep HBit = ?o!t.= 0 p!i
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D r i l l i g
R a t
e , # t < h
r
ydro!tati? re!!ure, 1,000! o# p!i
EFFEC$ %F ACG RESSRE0 " ,000 p!i
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35Drillig $ime, day!
Depth,
#t
Drilled ith ga!
Drilled ith mud
EFFEC$ %F DR+&&+* F&+Dmud @!. ga!
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Depth,
#t
Rotatig $ime, hour!
EFFEC$ %F DR+&&+* F&+Dater @!. air
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RelativeDrillingRate,
%
%ld !tyle ater ?our!e Bit!
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EFFEC$ %F S%&+DS +* $E /D
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Hdrostati) Pressre radient
Fresh Water !ressre (radient @ +73**psi
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Hdrostati) Pressre
ith 14 lB
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Hdrostati) Pressre Re3ired
e+th-0.052
'essu'eWei&ht/ude1ui'ed =
What md 8eight is reired to9alance a pore pressre of 1+,+++psig at a ertical depth of 1.,+++ ftJ
12,000-0.05210,000Wei&ht/udeui'ed =
M = 16.!3 l"#gal