Drilling Rigs
A drilling rig is a machine which creates holes in the ground. Drilling rigs can be massive structures housing equipment used to drill water wells, oil wells, or natural gas extraction wells, or they can be small enough to be moved manually by one person.
Following parameters are used to select the suitable drilling rig for the project:
(1) Static tension in the fast line when upward motion is impending
(2) Maximum hook horsepower
(3) Maximum hoisting speed
(4) Actual derrick load
(5) Maximum equivalent derrick load
(6) Derrick efficiency factor
To estimate the cost of realizing a well as to perform economical evaluation of the drilling project, before commencing the project, so called AFE (Authority For Expenditure) has to be prepared and signed of by the operator. Within the AFE all cost items are listed as they are known or can be estimated at the planning stage. During drilling, a close follow up of the actual cost and a comparison with the estimated (and authorized) ones are done on a daily bases.
When preparing an AFE, different completions and objectives (dry hole, with casing and completion, etc) can be included to cost-estimate different scenarios.
Generally, an AFE consists of the following major groups:
(1) Wellsite preparation,
(2) Rig mobilization and rigging up,
(3) Rig Rental,
(4) Drilling Mud,
(5) Bits and Tools,
(6) Casings,
(7) Formation evaluation
The listed cost items and their spread are different at each company and can be different within one company (onshore-offshore, various locations, etc.).
Along with the well plan (well proposal) a operational schedule as well as a schedule of expected daily costs has to be prepared.
On of the most basic estimations of drilling costs, following parameters have been considered:
• cost per unit depth
• cost of bit
• fixed operating cost of rig per unit time
• depth drilled
• total rotation time during the bit run
• total non-rotating time during the bit run
• trip time
The drilling time can be estimated based on experience and historical penetration rates. Note that the penetration rate depends on: (1) type of bit used, (2) wear of bit used, (3) drilling parameters applied (WOB, RPM), (4) hydraulics applied (hydraulic impact force due to mud flow through nozzles), (5) effectiveness of cuttings removal, (6) formation strength and (7) formation type.
Therefore an analytic prediction of the rate of penetration (ROP) is impossible. Estimations are generally based on the assumption of similar parameters and historic ROPs.
NoDoC model for cost estimation of drilling combines time and technical parameters into a method that are based on the expereice, expertise and sience.
Following parameters are used to select the suitable drilling rig for the project:
(1) Static tension in the fast line when upward motion is impending
(2) Maximum hook horsepower
(3) Maximum hoisting speed
(4) Actual derrick load
(5) Maximum equivalent derrick load
(6) Derrick efficiency factor
To estimate the cost of realizing a well as to perform economical evaluation of the drilling project, before commencing the project, so called AFE (Authority For Expenditure) has to be prepared and signed of by the operator. Within the AFE all cost items are listed as they are known or can be estimated at the planning stage. During drilling, a close follow up of the actual cost and a comparison with the estimated (and authorized) ones are done on a daily bases.
When preparing an AFE, different completions and objectives (dry hole, with casing and completion, etc) can be included to cost-estimate different scenarios.
Generally, an AFE consists of the following major groups:
(1) Wellsite preparation,
(2) Rig mobilization and rigging up,
(3) Rig Rental,
(4) Drilling Mud,
(5) Bits and Tools,
(6) Casings,
(7) Formation evaluation
The listed cost items and their spread are different at each company and can be different within one company (onshore-offshore, various locations, etc.).
Along with the well plan (well proposal) a operational schedule as well as a schedule of expected daily costs has to be prepared.
On of the most basic estimations of drilling costs, following parameters have been considered:
• cost per unit depth
• cost of bit
• fixed operating cost of rig per unit time
• depth drilled
• total rotation time during the bit run
• total non-rotating time during the bit run
• trip time
The drilling time can be estimated based on experience and historical penetration rates. Note that the penetration rate depends on: (1) type of bit used, (2) wear of bit used, (3) drilling parameters applied (WOB, RPM), (4) hydraulics applied (hydraulic impact force due to mud flow through nozzles), (5) effectiveness of cuttings removal, (6) formation strength and (7) formation type.
Therefore an analytic prediction of the rate of penetration (ROP) is impossible. Estimations are generally based on the assumption of similar parameters and historic ROPs.
NoDoC model for cost estimation of drilling combines time and technical parameters into a method that are based on the expereice, expertise and sience.
