| [Preparation before drilling] |
- Inspect previous bit for body damage, lost cutters or inserts etc. make sure the well bottom no hard objects exist such as cutters, tungsten carbide and steel pieces. Clean the bottom if necessary.
- Handle the bit with care. Place the bit on wooden pad or rubber mat. Do not set the bit directly on the steel floor.
- Check the cutting elements for damage, inside of bit for any foreign matter and ensure that nozzle O-rings are in place. Install proper nozzles as the requirement.
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| [Making up the bit] |
- Clean and grease the pin or box.
- Fit the breaker to the bit, lower the drill string onto the pin and engage the threads.
- Locate the bit and breaker in the rotary busing, and make-up to the recommended torque.
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| [Tripping in the hole] |
- Remove the breaker and carefully lower the bit through the rotary table, BOP's and liner hangers.
- Note the presence and location of tight spots observed when pulling the previous bit out of the hole. Trip slowly through tight spots, dog legs or ledges.
- Wash the last three joints to bottom with full flow at 60 rpm.
- Approach the bottom cautiously by observing the weight and rotary torque indicators. Tag bottom gently and pick up off bottom approximately half meter. Circulate for 5 to 10 minutes with full flow.
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| [Reaming] |
- Reaming long sections of undergauge hole is not recommended.
- If reaming is necessary, Ream slowly and avoid high torque with full flow at 60rpm and 10 to 20kn ( weight-on-bit)
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| [Bit Break-in] |
- Lower bit to bottom with full flow.
- Use 10 to 20kn. weight-on-bit and 60rpm to establish the bottom-hole pattern with slowly drilling at least one meter.
- Increase the weight in 10KN increments to determine optimum drilling weight-on-bit.
- While maintaining constant weight-on-bit, vary the rotary speed to determine optimum drilling parmeters.
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| [Drilling Ahead] |
- Reduce rotary speed in abrasive or hard sand stringers to increase bit life.
- Adjust the rotary speed and weight-on-bit as formation changes or stringers are encountered to maintain optimum drilling performance.
- After making connections note the following points:
◎Reset pump strokes and check standpipe pressure.
◎Before bit approach the bottom pump and slowly lower bit to bottom at 60rpm before drilling.
◎Add weight slowly to attain previous weight-on-bit, then increase rotary speed to previous rpm.
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