Tech Report Quantity of Mud Lost to Highly Fractured Limestone Reduced by 97%
Circulation was performed at the top of the FORM-A-BLOK AS pill, increasing the flow rate gradually.
FORM-A-BLOK AS
Acid-soluble lost circulation pill
The FORM-A-BLOK AS acid-soluble 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 pill which, depending on the application, dewaters or deoils rapidly to form a high-strength plug.
The pill can be used in water-base or nonaqueous drilling fluids and at temperatures up to 350 degF [177 degC]. The recommended concentration of FORM-A-BLOK AS pill is 32-lbm/bbl [91-kg/m3] for all fluid densities in freshwater, seawater, or oil- or synthetic-base systems. Mixing a water-base pill will provide the maximum strength. The slurry is weighted with SAFE-CARB ground marble bridging agent. M-I SWACO recommends continuously agitating the pill until it is pumped and pulling the pump screens prior to pumping.
Water-Based Pill Formulation
| Density, lbm/galUS [Relative Density] | Freshwater Volume, bbl | FORM-A-BLOK AS Pill Concentration, lbm/bbl | SAFE-CARB 40 Agent Concentration, lbm/bbl |
|---|---|---|---|
| 9 [1.08] | 0.95 | 32 | 14 |
| 10 [1.20] | 0.88 | 32 | 81 |
| 12 [1.40] | 0.75 | 32 | 210 |
| 14 [1.60] | 0.62 | 32 | 340 |
NAF-Based Pill Formulation (Based on 0.81-Relative-Density Oil)
| Density, lbm/galUS [Relative Density] | NAF Volume, bbl | FORM-A-BLOK AS Pill Concentration, lbm/bbl | SAFE-CARB 40 Agent Concentration, lbm/bbl |
|---|---|---|---|
| 9 [1.08] | 0.86 | 30 | 100 |
| 10 [1.20] | 0.80 | 32 | 160 |
| 12 [1.44] | 0.68 | 32 | 280 |
| 14 [1.68] | 0.56 | 32 | 397 |
| Physical Properties | |
|---|---|
| Physical appearance | Gray powder |
| Relative density | 2.50–2.60 |
| Solubility in water | Insoluble |
| Solubility in 15% HCl <212 degF [100 degC] | 92%–96% |
| Solubility in 5% HCl >212 degF [100 degC] | 92%–96% |
Toxicity and handling
Bioassay information is available upon request. Handle as an industrial chemical, wear protective equipment, and observe the precautions described in the material safety datasheet (SDS).
Packaging and storage
The FORM-A-BLOK AS pill is packaged in 32-lbm [14.5-kg] multiwell paper sacks. Store in a dry, well- ventilated area. Keep container closed when not in use. Store away from incompatibles. Follow safe warehousing practices regarding palletizing, banding, shrink-wrapping, and stacking.
Applications
- Wellbore strengthening
- Partial to wide-ranging severe lost circulation
- Openhole remedial and preventive lost circulation squeezing
- Improving casing shoe integrity
- Cased hole squeezing for sealing perforations and casing leaks
Advantages
- Compatibility with freshwater, seawater, and nonaqueous drilling fluid (NAF)
- Temperature stability up to 350 degF [177 degC]
- Easy mixing in density up to 14.0 lbm/gal [1.68 relative density]
- Simplified deployment that requires no activator or retarder
- Temperature-independent plug formation
- Premixable in advance of pumping if pill is continuously agitated
Helpful links
About SLB