About API 13A Section 12 Attapulgite
API 13A attapulgite is the clay viscosifier specified for drilling fluids made up with salt water. Obsidian Minerals produces this Section 12 grade, widely known as salt water gel or salt gel, for seawater, brackish water and saturated sodium chloride muds in which sodium bentonite cannot hydrate properly.
The reason is structural. Bentonite thickens when water enters between its platelets, and dissolved salt suppresses that swelling. Attapulgite works differently. Its needle-shaped crystals disperse under shear and form a random, interlocking lattice that holds water mechanically. Since the lattice does not depend on swelling, viscosity and gel strength are maintained in high-chloride brine and in make-up water carrying calcium and magnesium. Mud engineers use it to clean large top-hole sections drilled with seawater, to suspend cuttings and weighting material in salt-saturated systems, and to build viscous sweeps from the water already on location.
Every production lot is tested in our NABL-accredited laboratory against the three Section 12 requirements: a viscometer dial reading of at least 30 at 600 r/min in saturated salt water, residue above 75 µm of no more than 8.0 % by mass, and moisture of no more than 16.0 % by mass. Results appear on the batch Certificate of Analysis supplied with each shipment. The applicable API 13A edition is confirmed at order, and the grade is packed in bags or jumbo bags suited to rig-site and mud-plant handling.
Typical specifications
| Parameter | Typical Value | Test Method |
|---|---|---|
| Viscometer dial reading at 600 r/min, saturated salt water | ≥ 30 (API 13A requirement) | API 13A, Section 12 |
| Residue greater than 75 µm (wet screen) | ≤ 8.0 % by mass (API 13A requirement) | API 13A, Section 12 |
| Moisture | ≤ 16.0 % by mass (API 13A requirement) | API 13A, Section 12 |
| Typical 600 r/min dial reading, saturated salt water | 32–38 | API 13A, Section 12 |
| pH (5 % suspension in distilled water) | 7.5–9.5 | Internal method |
| Appearance | Free-flowing cream to light tan powder | Visual |
API 13A requirements are shown as stated for Section 12; the applicable edition should be confirmed at order. Other values are typical and for guidance only. Guaranteed limits are stated on the Technical Data Sheet and batch CoA.
Key features & benefits
Performs in salt water
Develops viscosity and gel strength in seawater, brackish make-up water and saturated sodium chloride brine, where conventional bentonite yields poorly. Rigs can mix with the water available on location instead of trucking in fresh water.
Tested to API 13A Section 12
Each lot is checked for 600 r/min dial reading in saturated salt water, wet-screen residue above 75 µm and moisture, the three API 13A Section 12 requirements, and the measured values are reported on the batch CoA.
No pre-hydration step
The needle-shaped crystals disperse under hopper and pump shear and build structure directly in brine. There is no need to pre-hydrate in a fresh water tank, which saves pit space and mixing time at the rig.
Suspension for cuttings and barite
Gel strength helps carry drilled cuttings up the annulus and keeps barite or other weighting agents suspended during connections and trips, supporting hole cleaning in salt-based mud systems.
Clear division of mud functions
Salt water gel supplies viscosity rather than filtration control. Pairing it with starch, PAC or other fluid-loss additives lets the mud engineer adjust rheology and filtrate independently to meet the well programme.
Applications
Seawater spud and top-hole muds
Offshore and coastal top-hole sections are often drilled with seawater. Attapulgite salt gel builds the viscosity needed to clean large-diameter holes without converting the system to fresh water.
Saturated salt muds through evaporites
Salt-saturated sodium chloride muds help prevent dissolution of halite beds and hole enlargement. Attapulgite stays effective at saturation, providing suspension alongside the fluid-loss polymers in the system.
Brackish and bore-well make-up water
Onshore rigs relying on brackish or bore-well water can hold consistent viscosity with less dependence on fresh water supply, which simplifies logistics on remote locations.
High-viscosity salt water sweeps
Viscous pills built with salt gel help lift cuttings from large-diameter or deviated sections. They can be mixed quickly in a slugging pit using the rig's existing salt water supply.
Usage & handling
- Typical field addition is 15–25 lb/bbl (approx. 43–71 kg/m³), adjusted to the mud programme and pilot test results.
- Add slowly through the mixing hopper into salt water with the highest shear available; viscosity develops as the needles disperse, and no fresh water pre-hydration is needed.
- Add starch, PAC or other fluid-loss additives separately, since attapulgite contributes viscosity and suspension but little filtration control.
- Store bags dry, under cover and off the ground, and reseal or use opened bags promptly so moisture stays within specification.
- Wear a dust mask and eye protection while mixing and follow the MSDS/SDS for handling and disposal guidance.
Packaging & supply
- 25 kg or 50 kg HDPE or paper bags for sack mixing at the hopper
- 1 MT or 1.2 MT FIBC jumbo bags for mud plants and bulk mixing systems
- Custom or private-label packaging for mud service companies on request
- Batch CoA, Technical Data Sheet and MSDS/SDS supplied with every shipment
Frequently asked questions
What is API 13A Section 12 attapulgite?
API 13A is the specification for drilling fluid materials, and Section 12 covers attapulgite. It sets three requirements: a 600 r/min viscometer dial reading of at least 30 when the clay is mixed in saturated salt water, residue above 75 µm of 8.0 % by mass or less, and moisture of 16.0 % by mass or less. Material meeting these limits is sold as API attapulgite or salt water gel.
Why use salt water gel attapulgite instead of bentonite in a brine mud?
Sodium bentonite needs fresh water to swell, and in seawater or saturated brine its yield falls sharply unless it is pre-hydrated and protected. Salt water gel attapulgite builds viscosity through the physical entanglement of its needle crystals, so salt has little effect on its performance. It can be added straight into the brine system, which is simpler and usually more economical on salt water wells.
Does API 13A attapulgite control fluid loss?
Only to a limited extent. The needle structure gives viscosity and gel strength but does not form a tight, low-permeability filter cake the way bentonite platelets do. In salt water muds, filtration is normally controlled with starch, PAC or similar polymers added alongside the attapulgite. Pilot testing the full formulation confirms filtrate against the well programme.
How is API 13A conformance shown for each shipment?
Each production batch is tested in our NABL-accredited laboratory using the API 13A Section 12 procedures, and the measured 600 r/min reading, residue and moisture are reported on the batch Certificate of Analysis. Please confirm the API 13A edition your tender references when ordering. Buyers are welcome to verify results with their own laboratory or a nominated inspection agency.
Can I get a sample of salt water gel for pilot testing?
Yes. Samples of API 13A attapulgite are available on request for laboratory and pilot testing in your own brine. Tell us the make-up water type, target mud weight and quantity required, and we will send the sample with its Technical Data Sheet and MSDS/SDS so your mud engineers can evaluate it against current supply.