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ATTATCHMEN7 A <br />Our research shows there to be several types of sulfate resistant cement <br />available and the cost is very similar to Type I Portland where we have checked. <br />There are two systems for cement classification. The API (American Petroleum <br />Institute) has developed one that identifies different categories as classes. The <br />ASTM (American Society for Testing and Materiaisj has developed another <br />system that identifies different categories as Types. The construction industry <br />uses the ASTM system. <br />The use of sulfate resistant cement is common practice in the oil and gas <br />industry. The recommendations of the API are currently being followed by <br />neighboring states for completion of virtually all oil and gas completions due to <br />the possible presence of SO4. <br />Two factors are commonly believed to affect cements sulfate resistance. <br />1. Grind or particle size. The finer the grind the better cement resists S04 <br />deterioration. <br />2. The C3A (Tricalcium Aluminate) content. The lower the C3A content the <br />more sulfate resistant the cement is. <br />The API classification scheme for sulfate resistant cement is denoted by a C3A <br />number from 1 to 10; 1 being more resistant than 10. <br />Class C, available in MSR (medium sulfate resistance) or HSR <br />characteristics (will set up in brine water) and a C3A number <br />ranging between 8 and 3. <br />Class G (HSR) cement has a C3A number less then 3. <br />Construction grade cements (readily found at local batch plants) include: <br />Portland or type I cement has no C3A limited number. <br />Type II cement (moderate sulfate resistance) generally has a C3A number <br />of less then 8. <br />Type V cement (high sulfate resistance) generally has a C3A number of less then <br />5. The sulfate resistance of Type V can also be achieved by blending Type II <br />with 20% Class Ffly-ash. This mixture is almost as common as Type I. <br />