Schlumberger

Case Study: FORM-A-BLOK Successfully Isolates Perforations to Reduce Losses, NPT

Challenge: After drilling the cement and shoe and 6 m (20 ft) of new formation, the operator conducted a Formation Integrity Test (FIT). With the objective of achieving a 14.0 lb/gal equivalent, the operator isolated the well with the Upper Pipe Rams (UPRs), lined up the rig choke and began pressuring up the wellbore. When 670 psi was held for 5 min., the operator decided to bump the pressure up to 1,000 psi. The well broke down at 933 psi and total returns were lost. As the operator had previously spotted and squeezed a 100 lb/bbl calcium carbonate pill to contain losses at the overlying perforations, it was suspected that the thief zone was immediately above the shoe.

Solution: The M-I SWACO fluids engineering team suggested the FORM-A-BLOK high-strength, high fluid loss pill be used to isolate the perforations and avoid further losses of the ULTRADRIL high performance water-base mud (HPWBM). The operator immediately displaces the well to seawater and pulled the BHA to 20 ft above the suspected top of the perforations. At the same time, the rig crew began mixing a 40 bbl FORM-A-BLOK pill at the suggested concentration of 40 lb/bbl.

Result: As a single-sack solution that works independently of time or temperature, FORM-A-BLOK required no accelerator or retarder, thereby making it mixed easily by rig personnel. Once pumped into the hole, the pill met all programmed objectives, including:

  • Generating good returns at surface
  • Allowing a successful displacement back to the ULTRADRIL HPWBM
  • Producing only trace amounts of FORM-A-BLOK at the flow line shakers during the displacement
  • Enabling the rig to pull out of hole (POOH), change the BHA and commence drilling operations


Download: FORM-A-BLOK successfully isolates perforations (0.18 MB PDF)

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“FORM-A-BLOK performed just as we proposed to our client and allowed us to continue operations without further Non-Productive Time (NPT).”
Frank Mamaril
Project Engineer
MI-SWACO