API Barite used for drilling petroleum wells can be black, blue, brown, buff, or gray depending on the ore body. It must be finely ground so that at least 97% of the material, by weight, can pass through a 200-mesh [75-micrometer (µm)] (Tyler) screen, and no more than 30%, by weight, can be less than 6 µm, effective diameter, which is measured using sedimentation techniques. The ground barite also must be dense enough that its specific gravity is 4.2 or greater, soft enough to not damage the bearings of a tricone drill bit, and both chemically inert and containing no more than 250 milligrams per kilogram (mg/kg) of soluble alkaline salts (American Petroleum Institute, 1993, p. 6-11). A small percentage of iron oxide is allowable. An additional feature of barite is noninterference with magnetic measurements taken in the borehole, either during logging-while-drilling or in separate drill-hole logging.
Barite, a name that was derived from the Greek word “barus” (heavy), is the mineralogical name for barium sulfate. In commerce, the mineral is sometimes referred to as “barytes.” As used in this report, the term “primary barite” refers to the first marketable product, which includes crude barite (run of mine) and the products of simple beneficial methods, such as flotation, heavy media separation, jigging, magnetic separation, tabling, and washing. Most crude barite requires some upgrading to minimum purity or density. api Barite that is used as an aggregate in a “heavy” cement is crushed and screened to a uniform size. Most api barite is ground to a small uniform size before it is used as a filler or extender, an addition to industrial products, or a weighting agent in petroleum well-drilling mud [American Petroleum Institute (API) or Oil Companies’ Materials Association (OCMA)] specification barite.
Density: 4.20 g/cubic cm, minimum
Water soluble alkaline earth metals as calcium: 250 mg/kg, maximum
Residue greater than 75 microns: 3.0 % by weight, maximum
Particles less than 6 microns in diameter: 30 % by weight, maximum
In addition to the above API barite specifications, some drilling companies also focus on heavy metals’ contents as specified by EPA:
Cadmium: 3 mg/kg, maximum
Mercury: 1 mg/kg, maximum
Additional heavy metals may also need to be taken into account, like silver, arsenic, chromium, copper, lead, selenium and zinc.
As with all the testing done at Ana-Lab, the barite testing is done to exacting API specifications, with fast turn-around time.