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' • 0 Pozmix Cements enough to cause settling prior to setting. These tests For high temperature conditions, chemical retarders conducted on 1 x 1 x 10 inch bars show that pozzolans can be added to Pozmix and portland cement for use in generally increase this expansion over that obtained with wells to 20,000 feet (6096 m). neat portland cement. This expansion characteristics Slurry Weights ' assists in obtaining better bonding and sealing. The slurry weight of Pozmix Cement is less than neat THE PHYSICAL PROPERTIES OF POZMIX cement because of the specific gravity of the Pozmix. CEMENT Pozmix has a specific gravity of 2.3 to 2.6 depending on the ' The properties of Pozmix Cement vary somewhat source, as compared to 3.1 to 3.2 for portland cement. from those of portland cement and other cementing Slurry Volume admixtures. For this reason the following discussion is Field practice indicates that Pozmix Cement offers ' presented. more fill-up per sack of material as compared to neat Pozmix Cement Mixtures cement. The increase in volume will be reflected in lower cementing costs. The ratio of Pozmix and portland cement used in ' most areas of the oil industry is 50-50 based on the absolute Waiting on Cement Time volume of approximately one sack of cement. A sack of The waiting time on cement is a factor which is cement (94 pounds/42.6 kg) has a bulk volume of dependent on many things such as temperatures,pressure, ' approximately one cubic foot which is composed of 0.52 type of job and strength desired before resuming drilling cubic feet of air (the void spaces) and 0.48 cubic feet of operations. solids.When the 0.48 cubic feet is converted togallons the The W.O.C. time of Pozmix Cement is generally ' number is 3.6 (13.63L), the actual space occupied by the consistent with normal practice for other types of cements solids of one sack of cement when mixed with water to or admixtures under the same conditions.Even on shallow form a slurry.These 3.6 gallons(13.63L)of actual cement surface pipe where low temperatures exist, Pozmix solids are referred to as the absolute volume of a sack of Cement can be adapted to fit the condition and have a ' cement. W.O.C. time comparable to neat cement. In many areas, When using a 50-50 Pozmix Cement mixture, 47 where such conditions are common,it is general practice to pounds of cement will occupy 1.8 gallons (6.81L) in the use calcium chloride with all or particularly that part of slurry and 37 pounds of Pozmix A will occupy 1.8 gallons Pozmix Cement around the lower joints of pipe on surface (6.81L); or both together will occupy 3.6 gallons (13.63L) jobs. (0.48 cubic feet). Admixtures to Pozmix Cement ' Volumes and Weights of Pozmix Cement The use of admixtures with Pozmix Cement compares very simiarly to that with portland cement. Bulk Vol. Absolute Total There are limitations, however, to such additives as (approx.) Volume Weight bentonite and perlites due to the reduction in strength. Portland Cement 1 cu. ft. 3.6 gallons 94 pounds Complete information on the effect of such (13.63 L) (42.6 kg) admixtures as calcium chloride,HR-4 retarder,Gilsonite, ' 50-50 Pozmix A 1 cu. ft. 3.6 gallons 84 pounds bentonite, CFR-2, Halad 9, perlite and salt on Pozmix Cement (13.63 L) (38.1 kg) Cement is given in the engineering data of the Pozmix . Cement Manual. Compressive Strength ' At early ages Pozmix Cement will exhibit lower strengths than portland cement. However,as the pozzolan reacts with the free lime liberated in the setting of cement, ' these strengths increase and the ultimate strength is more than straight cement.* These low early strengths, however,do conform to the current safe minimum of 500 ' psi as generally accepted by the industry for casing cementing jobs. Thickening Time The total thickening time for Pozmix Cement, as determined by the Pressure-Temperature Thickening- ""Chemistry of Cement and Concrete"by F. M. Lea and Time Tester,is comparable to neat portland slurries of the C. H. Desch same consistency. ' 3