Pre-Job Preparation for a TTCBP

The following recommendations will help to achieve a successful plug-back. Although some of these recommendations might not be feasible, it is important that the Project Engineer be aware of their importance.

1.If your well has a column of fluid to the surface and a positive shut-in tubing pressure, contact HPI for recommendations. Successful plug-back of these wells is very sensitive to pressure maintenance throughout the project. Wells with a gas cap are much less sensitive to pressure maintenance during plug-back operations. A positive shut-in tubing pressure with a gas cap is very common and not a serious concern.

2. Determine if one of the following deleterious elements is present at the plug setting depth:

Contact HPI for consultation if any one of these damaging elements is present at the plug depth. Their presence can reduce or eliminate the bond between cement and casing. Oil and condensate can retard cement to the point where it takes weeks for it to set. For best results, cement should be dumped in clean casing and clean wellbore fluids (fresh water or brines having less than 100,000 ppm salt concentration).

3.If possible, pump 5-10 tubing/casing volumes of sea water or other suitable brine into the well. This should flush the well and leave a clean fluid at the plug setting depth. After pumping, allow the well to stabilize for at least 48 hours prior to running the plug.

4.If the well is on gas lift, bleed all pressure off the casing and tubing. If possible, pump brine into the well as described in No. 3, above. Allow the well to stabilize for at least 48 hours prior to running the plug.

5.Generally, it takes days for a wellbore to achieve psuedo equilibrium. Fluid entering the wellbore and gas "percolating" into the wellbore can induce channels in a cement plug. Therefore, shut the well in and allow it to stabilize for at least 48 hours prior to running the plug. This will help to minimize the fluid and gas movement during plug-back operations.

6.Run a stiff full length drift down to the plug setting depth. The drift should have the same running diameter and length as the dump bailer tool string.

7.Read the Recommended HIP Running Procedures before commencing plug-back operations. These procedures address important operations which will help to maximize project success.

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