Case Study: FORM-A-SQUEEZE Seals Problematic Shoe

Allows Resumption of Drilling

Challenge: After cleaning cement to 9,090 ft (2771 m) within 22 ft (7 m) before the casing shoe, the operator began the 9 5/8-in casing leak off test (LOT) prior to beginning the horizontal section of the Corocoro field development well. The LOT failed as a total of 3000 psi of pressure was applied and could not be maintained. After drilling out the casing shoe and drilling 20 ft. (6 m) of rat hole to 9126 ft (2782 m), the operator discovered little or no cement around the casing shoe. Afterwards, the well was drilled to 9132 ft ( 2783 m) where a viscous pill was pumped and the returns to surface were observed as containing 50% cement, 30% clay and 20% sand. At this point, the bit was pulled up to 9128 ft (2782 m). The operator attempted to strengthen the formation and provide integrity to the casing shoe by pumping a pill consisting of SAFE CARB 20/40/250 formulation. After the operation proved unsuccessful, the operator decided to pump three cement slugs up to 50 ft (15 m) inside the casing. The second LOT also failed to hold pressure and bled off to 164 psi at 9132 ft (2783 m).

Solution: M-I SWACO proposed a sealing pill using a 10 lb/gal (1.2 sg) FORM-A-SQUEEZE high-fluid loss/high-solids slurry. The concentration of the recommended 45-bbl pill would include 75 lb/bbl FORM-A-SQUEEZE and 33 lb/bbl each of SAFE CARB 20, SAFE CARB 40 and SAFE CARB 250. Pumping of the plug would precede a pressurized cement treatment at the casing shoe.

Result: M-I SWACO pumped the FORM-A-SQUEEZE pill as per the operator’s specific request. The plug completely sealed the leaking casing shoe fracture with sufficient integrity to allow drilling to resume as programmed. No further cement squeezes were required. The opertor expressed satisfaction and certified the job as a complete success. The project reinforced the high performance characteristics of a FORM-A-SQUEEZE pill when formulated and applied to the client’s specific requirements.

Well Information
Location Offshore Eastern Venezuela
Rig type Jack-up
Field Corocoro Field
Well type Development
Directional hole 8 ½ in.
Casing diameter 9.625 in
Casing shoe 9,112 ft (2778 m)
Interval length 20 ft (6 m)
Fluid density 8.6 – 10.1 lb/gal (1.0 – 1.2 sg)

The Details

Once the FORM-A-SQUEEZE pill was mixed in the rig tanks, it was pumped and displaced with sea water. Once the column reached 9132 ft (2783 m) the pumping pressure stood at 320 psi at which point the pumps were stopped for 20 min. The bit was pulled up to 8396 ft (2559 m) where the annular was closed and the squeeze process began. The pressure increased to 147 psi, reaching up to 943 psi before the pump was stopped and the shut- in pressure observed for 20 min. Pressure fell to 532 psi, prompting the operator to again close the annular and proceed to squeeze.

When the pressure reached 1300 psi, behavior was observed for two hours. At the end of the observation period, the well exhibited 302 psi pressure and pumping continued until pressure increased to 1315 psi. Again, pumping was discontinued and the pressure observed for one hour, whereupon pressure had fallen to 522 psi before increasing and stabilizing at 793 psi.

The total pumped volume at the beginning of the test was 14.5 bbl, at which point the annular was open, flowing back a total of 2.5 bbl. The drill string was tripped in the hole to 9132 ft (2783 m) and circulated bottoms up with 50-bbl 10 lb/gal (1.2 sg) FLOPRO NT. Afterwards, the operator pulled up the bit to 9060 ft (2761 m) and performed a new LOT with the annular closed. A total of 3.25 bbl was pumped until the pressure reached 1086 psi and observed for 10 min. When the pressure reached 1024 psi, it was released and 3 bbl was returned to the active system. Using a maximum pumping rate, the FLOPRO NT successfully displaced the seawater from the hole at a displacement pressure of 1200 psi. After a flow check revealed no problems, the cleaning BHA was replaced with a directional assembly and drilling operations continued as programmed.

Download: FORM-A-SQUEEZE Seals Problematic Shoe (0.45 MB PDF)

Related services and products

Contact Us