The Situation

While drilling ahead at 624 m (2,047 ft) in the Dammam formation, the operator encountered total losses. At the same point in offset wells up to 17 cement jobs were required to cure losses and drill ahead.

The Solution

M-I SWACO recommended the operator employ its POLYSWELL lost circulation pill (LCM) on bottom where the losses were suspected of occurring. When properly mixed, spotted across the loss zone, and squeezed into the formation, POLYSWELL, in conjunction with CaCO3 F and M, and M-I SEAL*, has been shown to be an excellent solution to avoid additional non-productive time (NPT) associated with multiple cement jobs.

The Results

POLYSWELL effectively eliminated the losses and sealed off the suspected on-bottom thief zone and allowed the operator to drill ahead with no fluid-related problems.

The Details

The operator first began encountering losses at the rate of 160 bbl/hr while drilling the Dammam formation at 562 m (1,844 ft), increasing to an estimated 250-350 bbl/hr while drilling to 648 m (2,126 ft). Complete loss of returns occurred between 648-664 m. The operator reached the top of the Rus formation at 664 m where it was decided to conduct a cement job. After two cement plugs were set, complete losses ensued. Prior to initiating a third cement job, the operator decided to try a 60 lb/bbl LCM pill, comprising CaCO3 Fine and Medium and QUICK SEAL M. The pill was mixed in the slug pit and just before pumping was to begin 8 lb/bbl of POLYSWELL was added to the pill. After the LCM pill was displaced with 35 bbl water, the well was shut in and squeezed with 100 psi back pressure for 20 min. The third cement plug was then pumped and after waiting on cement, the operator went in the hole open ended. Losses were observed every 10 min., with static losses for the first 10 min. reduced to 10-12 bbl/hr. After 20 min., the losses were observed to have stopped.

Summary

POLYSWELL proved highly effective in mitigating total on-bottom losses and allowing drilling to proceed.

Experience shows it is most effective when mixed last in the LCM pill and pumped immediately, thereby allowing it to absorb water from the mud. It is further recommended these pills be pumped with an open-ended drilling assembly.

Questions? We’ll be glad to answer them.

If you’d like to know more about how POLYSWELL is working for our other customers worldwide, please call the M-I SWACO office nearest to you.