Please answer this question, its petroleum engineering class You have just finis
ID: 108902 • Letter: P
Question
Please answer this question, its petroleum engineering class You have just finished drilling a 7-7/8" vertical well on 16.0 ppg fluid to 15,000ft. The drill string is 5"20.5ppf drill pipe: ID= 4 214in: Capacity = 0 01725bbl/ft: Displacement = 0 0070bbl/ft Previously set casing is 9-5/8" 47.0ppf ID= 8 681 in and it is set from the surface down to 5500ft. Ignore BHA effects, assume all drill pipe. The pore pressure gradient of the formation at TD is 0.80 psi/ft. As the drill pipe is TOH, the fluid level will fall thus lowering the static bottom hole pressure (BHP). How many feet of drill pipe can be TOH, before the well needs re-filled to surface with fluid preventing an underbalanced condition?Explanation / Answer
The following points are necessary for TOH:
1. With a slurry of this nature it would be best to be placed open ended drill pipe or with a tubing stinger in place.
a. It can be pumped in placed through a bit but the personal pucker factor (PPF) registers off the chart. (high risk of getting a squeeze inside the drill string and not considered kosher)
b. If the operator cannot TOH to stand back the BHA and collars make sure the TFA of the jet nozzles is at least 1.0 inches.
c. If the slurry is placed with the drill bit in place, displace at 3.0 bbl per minute. If while displacing, the drill pipe pressure begins to increase (possibility indicating that the slurry is trying to plug off at the bit) slow down the pumping rate, DO NOT speed up the rate!
2. Mixing order of components is important.
3. Always and without fail, have the cement company that will pump the slurry do a thickening time (TT).
4. Always get rig samples of the mix water and the dry blended cement.
5. Always have 3 or 4 wet samples taken so they can be observed as the job progresses
ADDITIONAL LCM SQUEEZE SUGGESTIONS:
1. Pump LCM Slurry open-ended if possible.
2. If slurry must be placed through bit, it is suggested to use a choke nipple, smaller than the bit nozzle size, in the surface line. This will prevent plugging of the bit, and foreign objects can be easily removed at surface to avoid disrupting operations.
3. Always test slurry, to insure high fluid loss, prior to pumping.
4. Don’t hurry to build squeeze pressure. Patience and time are necessary to obtain a successful squeeze.
5. Don’t mix weighted slurry too far in advance of using it as all weighted fluids are subject to barite settling with time. If weighted slurry has been mixed prematurely, mix additional LCM to prevent long-term settling of barite.
6. Don’t contaminate LCM Slurry with low fluid loss mud.
7. Clean and flush all mixing lines to and from the cement mixing equipment to avoid contamination with any leftover cement.
8. Additional LCM’s may be added to the Slurry as follows: Open ended as much as an additional 50 ppb of CaCO3 or mix of products maybe added if un-weighted. Weighted slurries need to be pump able. Through a bit with jet nozzles none is recommended.
Pump slurry at 2 bpm until it reaches the end of the pipe. Before beginning the hesitation squeeze, check the annulus. If no fluid can be seen, use the fill-up line and fill the hole. Close annular bop, and pump at 1 ppm. This will direct the slurry down hole to the point of loss. If un-weighted pump the full open hole volume, plus an additional 20-30 bbls (3-5 M3) leaving the remainder of slurry in the drill pipe to squeeze with. If weighted pump the entire slurry volume and squeeze with the drilling fluid as this will prevent the weighted slurry from setting up in the pipe. After allowing the slurry to dehydrate check to see if the hole stands full. If the hole stands full then close pipe rams and pump through fill up line at a 1/4 to 1/2 bpm rate until 50 psi is obtained; then discontinue pumping for 10-15 minutes. Repeat this procedure with the goal to obtain the desired pressure. The hesitation squeeze allows the loss zone the best opportunity to become sealed-off. The final squeeze pressure should not exceed the equivalent maximum mud weight hydrostatic pressure for the interval. Once the desired pressure is obtained, shut down for 2-4 hours and wait for any additional fluid left in the slurry to bleed off. Two hours for a non-weighted slurry and 4 hours for weighted slurry. This method is the most effective but is best to limit drilling to about 500 feet because of the buildup of drill solids in the mud system.