Drilling Cost Per Foot

Using drilling parameters information to get best recommended bit to drill a new holes

Better drilling performance leads to less time and less operational cost - best bit or bits will be with less CPF and highest ROP in the same time exert high SE

Used equations

* CPF Cost Per Foot, * SE Specific Energy
Selection Criteria
Using set of offset wells’ drilling data which belong to the same area and have the following features
The same footage or nearly the same footage
The same depth interval
The same lithology and formation
The same operational drilling parameters
The same bit size and type
The bits should be 1^st run
Selection Software tool
DPA – Drilling Performance analyzer V 1.0.0.26

Selection criteria table of data for sack of verification and reference

Bit serial No.	Bit type	Bit size (in)	Supplier	Drilled (m)	CPF ($/ft)	On bottom ROP (m/hr)	SE /1000 (mj /Cu.m)	Bit Price ($)	Nozzles numbers and sizes
11119703	Rock bit	12 ¼	Security DBS	1292	1.84	32.08	13.7	7,800	3 * 18
11258480	Rock bit	12 ¼	Security DBS	1304	1.82	35.56	34.3	7,800	3 * 16
11366593	Rock bit	12 ¼	Security DBS	1312	3.27	31.14	27.2	14,091	3 * 18
7211634	PDC	8 ½	Hughes Christensen	1817	9.84	24.55	72.6	58,684	6 * 13
7211633	PDC	8 ½	Hughes Christensen	1418	14.83	11.66	204.4	68,988	6 * 14
7125529	PDC	8 ½	Hughes Christensen	1793	14.66	32.25	110.8	86,240	4 * 16

Result

The best recommended bits to drill 12 ¼ ‘’ and 8 ½’’ inch holes will respectively as follows

Bit serial No.

Bit type

Bit size (in)

Supplier

Drilled (m)

CPF ($/ft)

On bottom ROP (m/hr)

SE /1000

(mj /Cu.m)

Bit Price ($)

Nozzles numbers and sizes

11258480

Rock bit

12 ¼

Security DBS

1304

1.82

35.56

34.3

7,800

3 * 16

7211634

PDC

8 ½

Hughes Christensen

1817

9.84

24.55

72.6

58,684

6 * 13

Graphical output results

CPF - Chart -1

Best ROP for 12 ¼ ‘’ rock bit , SN 11119703

Best ROP for 8 ½ ‘’ PDC, SN 7211634

MSE- chart-3

MSE is valuable because it helps identify inefficiencies in the drilling process

Drillers should strive to keep MSE as low as possible and Rate of Penetration (ROP) as high as possible, by varying Weight on Bit (WOB), rotary speed, and mud flow within normal operating limits.

Drilling engineers want to hold MSE as close as possible to a formation’s true compressive strength. Unexpected changes in MSE may indicate changes in rock properties, or drilling inefficiency, or both.

Drilling Bits Recommendations