# Questions

1. 1 An operator in hard-rock country wants to finish his well with 5-in. production casing. He will need to run four strings (including the production casing) during the course of the well. What's the smallest conductor pipe he can use? What size would you recommend? If the well is in bad crooked-hole country, what casing program would you recommend?
2. 2 An operator is drilling a 12]/4-in. hole He plans to run 95/n-in. intermediate casing, drill out with an fi'/^-in. bit, and then run a 7-in. string at TD (total depth). This will accommodate a dual completion.

A kick is taken and casing (or a liner) must be run prematurely. Design an alternative casing geometry and explain your reasoning. What size production string do you believe to be most desirable? What are the potential problems? Would you underream a section to avoid clearance problems?

6.3 You set and cement 200 ft of 1 F/i-in. surface casing. While circulating it out, the derrickman notices mud bubbling up outside the easing. What possible alternatives exist for this problem?

Fig. 6-3 Casing and bit size selection chart (Courtesy of Oil and Gas Journal)

Bit Planning

Selecting the proper bits for a well is an important decision that affects the overall well cost. Many factors must be evaluated:

• bit cost
• expected parameters (i.e., turbines, rotary drilling, air operations)
• formation types and properties
• mud systems
• rig cost

The emerging technology for bit design adds additional significance when evaluating these parameters.

Drilling optimization can be viewed in three distinct phases: I Selecting the proper bit for the drilling conditions.

2, Monitoring the drilling conditions on the prospect well so drilling performance is at least equal to or above the average in the particular area.

3. Implementing a bit weight-rotary speed program from theoretical calculations that will improve drilling performance above the best wells in the area.

Generally, the last phase is difficult to implement in a one- or two-well drilling program. Unfortunately, the lirst two phases are often neglected, even though they require only a relatively simple evaluation of offset well data. This text will be restricted to covering the first two phases of drilling optimization.

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### Responses

• PHILLIPP DIEDERICH
What is the question for drilling engineer equipment?
8 years ago