FORM-A-BLOK High-Performance, High-Strength Lost Circulation Pill | SLB


High-performance, high-strength lost circulation pill

Schlumberger Oilfield Services

The FORM-A-BLOK high-performance, high-strength lost circulation pill is a single-sack proprietary blend designed for wellbore strengthening applications and a wide variety of lost circulation scenarios, including fractures and matrix permeability.

This product is applied in the form of a squeeze pill which, depending on the application, dewaters or deoils rapidly to form a high-shear-strength plug.

Remedial lost circulation treatments

The FORM-A-BLOK pill can be used in water-based or non-aqueous drilling fluids (NAF) for wellbore strengthening applications and to cure losses extending from partial to a wide range of severe lost circulation scenarios, at temperatures up to at least 350 degF [177° C]. The FORM-A-BLOK pill is designed to be used for: wellbore strengthening applications, curing partial to wide ranging severe loss situations, open hole remedial and/or preventive lost circulation squeeze, improving casing shoe integrity, and cased-hole squeeze for sealing perforations and casing leaks.


The recommended concentration of the FORM-A-BLOK pill is 114 kg/m3 [40 lb/bbl], for fluid densities up to 16 lb/galUS [1.92 sg] in freshwater, seawater or base oil/synthetic (NAF) systems. Fluid densities of 16 lb/galUS or higher require less FORM-A-BLOK pill; 86 kg/m3 [30 lb/bbl] for water-based pills and 57 kg/m3 [20 lb/bbl] for NAF-based pills. While the FORM-A-BLOK pill can be mixed with oil- or synthetic-based fluids, mixing a water-based pill will provide the maximum strength. The slurry can be weighted with barite, calcium carbonate or heavy brine. It is recommended to continuously agitate the pill until pumped and to pull pump screens prior to pumping.

Single-sack system, though higher densities may require the addition of a thinner
Temperature stable to at least 350 degF [177 degC]
Compatible with freshwater, seawater, brines, and NAF


  • Quick-acting plug for wellbore strengthening and lost circulation applications
  • Single-sack system, though higher densities may require the addition of a thinner
  • Compatible with freshwater, seawater, brines, and nonaqueous drilling fluids
  • Temperature stable to at least 350 degF [177 degC]
  • Can be mixed as a pill at densities of up to 18.0 lbm/galUS [2.16 sg]
  • Easy to mix and pump with standard rig equipment
  • Does not require an activator or retarder
  • Does not depend on time or temperature to form a rigid plug
  • Can be premixed well in advance of pumping provided pill is agitated continuously


Approximately 35% acid soluble

Toxicity and handling

Bioassay information is available upon request. Handle as an industrial chemical, wearing protective equipment and observing the precautions described in the safety data sheet (SDS).

Packaging and storage

The FORM-A-BLOK pill is packaged in 20-lbm [9-kg] multiwall paper sacks. Store in a dry, well-ventilated area. Keep container closed. Store away from incompatibles. Follow safe warehousing practices regarding palletizing, banding, shrink-wrapping, and stacking.