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• $ Pozmix Cements The use of Halliburton's bulk cement blending corresponding Portland cement. The rate and amount of equipment makes it possible to properly proportion this heat generation accompanying this reaction is dependent material with either portland cement or hydrated lime into upon the character and fineness of the pozzolan.*The heat ' blends which are offered to the oil industry under the liberated in the hydration of Pozmix Cement is sufficient ' trade names of Pozmix Cement, Halliburton "Light" to locate the fill-up behind a cemented casing by the use of Cement and Pozmix 140, respectively. a temperature survey. Field practice confirms the location of Pozmix Cement with temperature surveys at periods ' ADVANTAGES OF POZMIX CEMENT IN OIL comparable to those for neat cement. WELL CEMENTING Water Solids Ratios Pozmix Cement has been in general use throughout The ratio of solids to water in Pozmix Cement is such ' the United States and Canada as well as in many other that a large portion of the slum volume is occupied with parts of the world since 1949. Many thousands of wells solid cementitious material. Unlike some additives to oil have been cemented with this type of material. Due to its well cements, Pozmix Cement does not require large special properties, it has had wide usage under diversified volumes of water to obtain pumpable slurries with ' field conditions. Supported by extensive laboratory data satisfactory properties. Since the use of excessive water is for various applications in oil well cementing, Pozmix well known to be detrimental to the qualities of cement, Cement offers these significant advantages: the use of Pozmix Cement offers an improvement over ' Lighter Weight Slurries most other types of oil well cementing admixtures. A characteristic of Pozmix cementing slurries is a Low Permeability reduction of slurry weights with a minimum quantity of The combination of Pozmix with the soluble ' water. Pozzolans have a specific gravity of 2.3 to 2.6 compounds formed during the hvdration of cement makes depending on the source, as compared to 3.1 to 3.2 for this material less subject to the leaching action of portiand cement. This difference results in a lighter formation waters and maintains less permeability over a ' weight slum for Pozmix Cement as compared to portland longer period of time. cement slurries of similar consistency. The reduction of slum density ultimately results in an increased fill-up of Permeability measurements have been made on cement between the casing and formation for a given cement containing 0 to 65percent Pozmix setunder e , hydrostatic pressure.The use of a light weight slurry will, conditions ranging from 800 (271C) to 200'F (930 C)and in many cases, greatly assist in the protection of highly 1,000 (6895 kPa) to 7,500 (51713 kPa) pounds per square `- permeable formations from excessive pressure during inch pressure. These permeabilities were less than one- cementing. tenth millidarcy in all cases. Economic Savings Pumpabilt'ty Pozmix Cement offers the oil industry a material The addition of Pozmix to portland cement reduces having premium properties at a substantial monetary the thixotropic or gelling action often experienced with saving in most areas. neat cement slurries. This gelation characteristic could be detrimental if the movement were stopped while mixing or ' Resistance to Corrosion displacing neat cement that had not reached its maximum Probably the most important factor that has led to the thickening time. use of pozzolans in concrete has been the increased Laboratory tests, confirmed by field performance, resistance that is thus gained to attack by sea water.*The have shown that Pozmix Cement may often be allowed to increased resistance to sulfate attack obtained by the set in a well under static conditions for long periods of time addition of pozzolanic materials to cement is attributed to and still be moved with no appreciable increase in pump the removal of free calcium hydroxide formed in the pressure. ' hydration of portland cement, by combination with the Volume Change on Setting pozzolan.** Much research work has been done by the Chemical Laboratory tests at temperatures between 1000 ' Research & Development Department of Halliburton in (380C) and 1800F (820C) show that both Portland and evaluating the chemical resistance obtained by the use of Pozmix Cement tend to expand slightly upon setting, if pozzolans in oil well cementing slurries. Results indicate mixed with the proper amount of water and maintained in ' the resistance of common construction cement to sulfate a moist atmosphere. The proper amount of water is that corrosion is improved by the addition of an equal absolute amount which will produce a pumpable slum but not volume of pozzolan to the cement. *^Chemisrry of Cement and Corscrere"by F.M. Lea andC. ' Low Heat of Hydration H. Desch The heat of hvdration of any mixture of pozzolan and **"What You Should Know About Pozzolans" by cement is less than that of the same weight of Raymond E. Davis. 2