Lost circulation materials (LCM) have traditionally seen wide usage in drilling mud and drilling cementing operations. However, the use of LCM in remedial coiled tubing unit (CTU) cement work has been avoided in the past due to concerns that plugging could occur in the coiled tubing nozzle ports with the potential for cementing up an entire string of coiled tubing.

In certain types of problem wells at Prudhoe Bay, standard CTU squeeze cementing techniques have been unable to effect the desired zonal isolation. Despite multiple CTU squeeze attempts and large volumes of cement pumped in these wells, significant squeeze pressures could not be achieved.

Cement slurries containing LCMs were field tested through coiled tubing in an attempt to squeeze these problem wells. This paper will:

  1. Examine the most common mechanisms for the failure of CTU remedial cement squeeze operations in problem wells at Prudhoe Bay.

  2. Look at recent experimentation with different types of LCM used in CTU squeezes in Prudhoe Bay wells.

  3. Present several case histories of squeezes performed on severe problem wells with one particular LCM, an expanded soil aggregate. So far, this particular LCM has been highly successful in achieving CTU squeezes in problem wells.

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