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Ptressure testing of casing cementesd with inner string
06 February 2020
We have lowered a 18-5/8 casing to a depth of 8500 ft and cemented the casing with inner string. The shoe track of the casing is a single joint of casing with stab in flaot collar at 40 ft above the shoe.

The plan is to RIH with 16 '' bit upto stab in float collar and  pressure test the casing with 8.9 ppg water based mud to 4000 psi . Drill out stab in float collar and 15 ft of cement and retest the casing to 4000 psi. The fracture gradient at shoe is approx. 3200 psi. I am not in agreement with pressure testing the casing to 4000 psi after drilling out the stab in float collar and cement.with just 25 ft of grey cement for a high possibility of communication and breaking the formation at shoe. My suggestion is to pr.test  upto 3100 psi (required FIT is to a pressure of 3000 psi). Any other suggestions
1 answer(s)
Dan
Workover Engineer
SPREAD Associates
Total Posts: 16
Join Date: 01/08/18

Hi Prasad,

You shall look for the reason such pressure test value is required (basically identify the risk covered by this control measure, pressure test to be 4,000 psi).

Here are some guidelines for pressure test value:

- the pressure applied at the face of the perforations is predetermined at the job-design stage. It may be the reservoir pressure, but should not exceed the formation fracturing pressure.

- before drilling the cement plug, 80% of the minimum yield of the weakest point shall be considered as pressure test value.

- once casing shoe has been drilled, the pressure at the casing shoe shall be larger than the expected to be applied at this point during drilling the next phase (normally 0.65 lb/ft).

 

Dan

Posted by

Prasad Vasireddi

Senior Drilling Supervisor

Kuwait Oil Company

Total Posts: 1
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