Where sodium chloride is used in a well

The practical limit is density. A saturated sodium chloride brine reaches about 10.0 lb/gal (about 1.20 specific gravity) at ordinary temperatures, at roughly 26% salt by weight. Beyond that, operators turn to calcium chloride, bromide or formate brines. Completion brines as a class range from about 8.4 to over 20 lb/gal (1.0 to 2.4 g/cm³), according to SLB’s oilfield glossary; sodium chloride covers the lower, cheaper end of that range.

Where salt formations are drilled

Thick evaporite sequences are a routine part of drilling in several of the world’s main basins: the South Oman Salt Basin, salt sections in Kuwait and elsewhere in the Gulf, the pre-salt fields offshore Brazil and Angola, where wells pass through very thick salt layers, and the salt structures of the Gulf of Mexico. Each requires fluids that do not dissolve the salt, either salt-saturated water-based systems or non-aqueous fluids. Salt is also used in completions everywhere, whether or not salt formations are present.

“API grade salt” — check what it means

This is the most important section of this page.

Drilling salt is often advertised as “API grade”. Buyers should ask which document that refers to. API Specification 13A is the industry specification for drilling-fluid materials. It covers weighting agents and viscosifiers such as barite, haematite, bentonite and other clays, along with certain polymers. As far as we have been able to establish, it contains no specification for sodium chloride. If a supplier tells you their salt is “API certified”, ask for the specification number and the clause. If they cannot produce it, the phrase is marketing.

The impurities that matter

Washed Indian solar salt typically reaches 99.0–99.4% NaCl on a dry basis, and vacuum salt usually 99.8% or more, according to Salt Partners (2021). For most salt-saturated muds, washed solar salt is adequate and economical. For clear completion brines, the insolubles figure, not the NaCl figure, usually decides whether washed salt is good enough or vacuum salt is worth its premium.

Packaging for the rig

Oilfield salt travels further than most salt: from the port to a supply base, onto a supply vessel or a truck to a remote desert location, then onto a rig deck, often in heat and humidity. Packaging that works in a warehouse can fail on that journey.

Specification: what should be in the contract

Where Indian drilling salt fits

Trade statistics for salt (HS 2501) do not separate drilling grade from other salt, so there is no reliable figure for the oilfield share of India’s exports and we will not invent one. What can be said is geographical. Gujarat, which produced about 85% of India’s salt in 2021-22 according to the Indian Bureau of Mines, is a short voyage from the Gulf oilfields, and its ports — led by Deendayal (Kandla), which handles more than 80% of Gujarat’s salt exports — ship salt every day of the year. For buyers in Oman, the UAE, Kuwait, Saudi Arabia, Iraq and East Africa, that means short transit times and frequent sailings; for West Africa and Latin America, Indian salt competes on price but with longer transit and higher freight, which is why this guide is published in English, Arabic, Spanish, Portuguese and French.

Packing: private labelling from 1 kg to 50 kg, and bulk shipments

RNG Agro Exports offers private labelling from 1 kg to 50 kg pack sizes, and we also handle bulk shipments. For mud companies and distributors who supply rigs under their own name, we print sacks and big bags with your brand, product name, lot number and handling instructions, in the languages your locations require.

Working with RNG Agro Exports

We are based in Rajkot, Gujarat, in the state that makes about 85% of India’s salt, and we supply washed and vacuum salt from qualified producers there. For oilfield buyers, what we offer is a written specification with real numbers, a certificate of analysis for every lot, packaging specified for the journey to the rig rather than to a warehouse, and delivery dates we can keep. If your completion brine needs vacuum salt, we will tell you; if washed salt will do, we will tell you that too.

Frequently asked questions

What is drilling grade salt used for?

Mainly three things. First, salt-saturated water-based drilling fluids, used when a well penetrates evaporite formations: saturating the water phase with sodium chloride stops the mud from dissolving the salt and enlarging the hole. Second, completion and workover brines: sodium chloride brine is a solids-free well-control fluid, denser than fresh water and without solids that could damage the producing formation. Third, cementing across salt zones, where salt is added to the slurry so it does not dissolve the formation it is meant to seal. Saturated sodium chloride brine reaches about 10.0 lb/gal, or about 1.20 specific gravity, at roughly 26% salt by weight; heavier fluids use calcium chloride, bromide or formate brines.

Is there an API specification for drilling salt?

As far as we have been able to establish, no. API Specification 13A, the industry specification for drilling-fluid materials, covers weighting agents and viscosifiers such as barite, haematite, bentonite and other clays, along with certain polymers, but it does not appear to contain a specification for sodium chloride. If a supplier describes salt as “API grade” or “API certified”, ask for the specification number and clause. Without an industry specification, the buyer’s own purchase specification is the only enforceable standard, so it should state NaCl minimum, insolubles maximum, calcium and magnesium maxima, moisture, particle size, additives, packaging and documentation in numbers.

Which impurities matter most in drilling salt?

Insolubles, calcium and magnesium, and moisture. Insolubles become unwanted solids in the mud and add load on solids control; in completion brines, which are filtered to be clear and solids-free, they add directly to filtration time and cost. Calcium and magnesium can interfere with polymers, other mud additives and clay behaviour, so maxima keep fluid chemistry predictable. Moisture causes caking in sacks and big bags, especially in hot, humid supply bases and on deck, which slows mixing and can block hoppers. Sulphate matters if barium or calcium brines are in use. Washed Indian solar salt typically reaches 99.0–99.4% NaCl, and vacuum salt usually 99.8% or more; for clear completion brines, the insolubles figure usually decides which grade is needed.

What packaging should drilling salt come in?

Packaging chosen for the journey to the rig, not to a warehouse. The most common rig sack is 25 kg, because of manual-handling limits; 50 kg sacks suit supply bases and mixing plants with mechanical handling, subject to local handling rules. Sacks should be woven polypropylene with a polyethylene liner or laminated film, UV-resistant for outdoor storage, palletised and shrink-wrapped. Big bags of about one tonne suit rigs and plants with bulk-bag dischargers; specify the safe working load and the safety factor, which ISO 21898 sets at 5:1 for single-trip and 6:1 for multi-trip bags. Small 1 kg to 5 kg packs labelled with the bulk lot number are useful for mud-lab testing.

Do you offer private labelling and bulk shipments for drilling salt?

Yes. RNG Agro Exports offers private labelling from 1 kg to 50 kg pack sizes and also handles bulk shipments. For mud companies and distributors who supply rigs under their own name, we print sacks and big bags with the customer’s brand, product name, lot number and handling instructions in the languages each location requires. Bulk is available as loose bulk in containers for brine plants and liquid-mud plants, quoted on enquiry. Tell us the end use, the destination supply base, the monthly quantity and your packaging and documentation requirements, and we will quote the delivered cost so that you can compare origins on the figure that matters.

• Mainly three things. First, salt-saturated water-based drilling fluids, used when a well penetrates evaporite formations: saturating the water phase with sodium chloride stops the mud from dissolving the salt and enlarging the hole. Second, completion and workover brines: sodium chloride brine is a solids-free well-control fluid, denser than fresh water and without solids that could damage the producing formation. Third, cementing across salt zones, where salt is added to the slurry so it does not dissolve the formation it is meant to seal. Saturated sodium chloride brine reaches about 10.0 lb/gal, or about 1.20 specific gravity, at roughly 26% salt by weight; heavier fluids use calcium chloride, bromide or formate brines.
• As far as we have been able to establish, no. API Specification 13A, the industry specification for drilling-fluid materials, covers weighting agents and viscosifiers such as barite, haematite, bentonite and other clays, along with certain polymers, but it does not appear to contain a specification for sodium chloride. If a supplier describes salt as “API grade” or “API certified”, ask for the specification number and clause. Without an industry specification, the buyer’s own purchase specification is the only enforceable standard, so it should state NaCl minimum, insolubles maximum, calcium and magnesium maxima, moisture, particle size, additives, packaging and documentation in numbers.
• Insolubles, calcium and magnesium, and moisture. Insolubles become unwanted solids in the mud and add load on solids control; in completion brines, which are filtered to be clear and solids-free, they add directly to filtration time and cost. Calcium and magnesium can interfere with polymers, other mud additives and clay behaviour, so maxima keep fluid chemistry predictable. Moisture causes caking in sacks and big bags, especially in hot, humid supply bases and on deck, which slows mixing and can block hoppers. Sulphate matters if barium or calcium brines are in use. Washed Indian solar salt typically reaches 99.0–99.4% NaCl, and vacuum salt usually 99.8% or more; for clear completion brines, the insolubles figure usually decides which grade is needed.
• Packaging chosen for the journey to the rig, not to a warehouse. The most common rig sack is 25 kg, because of manual-handling limits; 50 kg sacks suit supply bases and mixing plants with mechanical handling, subject to local handling rules. Sacks should be woven polypropylene with a polyethylene liner or laminated film, UV-resistant for outdoor storage, palletised and shrink-wrapped. Big bags of about one tonne suit rigs and plants with bulk-bag dischargers; specify the safe working load and the safety factor, which ISO 21898 sets at 5:1 for single-trip and 6:1 for multi-trip bags. Small 1 kg to 5 kg packs labelled with the bulk lot number are useful for mud-lab testing.

Why this matters. With no industry specification to rely on, your purchase specification is the only specification. A mud company or operator that writes “drilling grade NaCl, API” on a purchase order has, in practice, specified nothing enforceable. Write the numbers instead: NaCl minimum, insolubles maximum, calcium and magnesium maximum, moisture, particle size, packaging and lifting standard. It is not more work than writing “API grade”. It is the work that the phrase was pretending to do.