System, apparatus and methods for blending cement

A system for blending cement and at least one additive during a blending job to create a cement slurry for use in an underground hydrocarbon well, the system comprising:

• a mixing tub having an upper end and a lower end and at least one outer wall extending therebetween, at least one inflow port formed in said outer wall and configured to allow the flow of at least one among cement and at least one additive into said mixing tub to be used to create the cement slurry, and at least one discharge port formed in said mixing tub and configured to allow the discharge of cement slurry from said mixing tub;
• at least first and second adjacent blenders associated with said mixing tub, each said blender having at least a first elongated, rotatable, mixing blade extending into said mixing tub, said first mixing blade of said first blender being configured to rotate in a direction opposite to the rotational direction of said first mixing blade of said second blender;
• and
• at least one inner discharge tube and at least one outer discharge tube disposed within said mixing tub, said inner discharge tube being positioned concentrically within said outer discharge tube, said inner and outer discharge tubes having respective open upper and lower ends, said respective upper ends of said discharge tubes being positioned in said mixing tub closest to said upper end of said mixing tub and said respective lower ends of said discharge tubes being positioned in said mixing tub closest to said lower end thereof, said inner discharge tube being in fluid communication with at least one said discharge port of said mixing tub, wherein said discharge tubes are configured to allow cement slurry to flow from said mixing tub into said upper end of said inner discharge tube, through said inner discharge tube and out said mixing tub through said at least one discharge port therein,
• each said discharge tube having a wall extending between said upper and lower ends thereof and at least one window formed in said wall of each said discharge tube, at least one said window of said outer discharge tube being alignable over at least one said window of said inner discharge tube, at least one among said inner and outer discharge tubes being selectively movable relative to said other discharge tube to move said respective alignable windows thereof between at least one aligned position and at least one misaligned position, said windows in said aligned position allowing the flow of cement slurry therethrough from said mixing tub into said inner discharge tube, and said windows in said misaligned position disallowing the flow of cement slurry through said windows.

System for blending cement and at least one additive during a blending job to create a cement slurry, the system comprising:

• a mixing tub having an upper end and a lower end and at least one outer wall extending therebetween, at least one inflow port formed in said outer wall configured to allow the flow of at least one among cement and at least one additive into said mixing tub to be used to create the cement slurry, and at least one discharge port formed in said mixing tub and configured to allow the discharge of cement slurry from said mixing tub;
• at least first and second adjacent blenders associated with said mixing tub, each said blender having at least a first elongated, rotatable, mixing blade extending into said mixing tub, said first mixing blade of said first blender being configured to rotate in a direction opposite to the rotational direction of said first mixing blade of said second blender, said blenders being configured to mix the cement and at least one additive to form the cement slurry within said mixing tub;
• and
• at least one inner discharge tube and at least one outer discharge tube disposed within said mixing tub, said inner discharge tube being positioned concentrically within said outer discharge tube, said inner and outer discharge tubes having respective upper and lower ends, said discharge tubes being configured to allow cement slurry to flow from said mixing tub into said upper end of said inner discharge tube, through said inner discharge tube, out of said lower end of said inner discharge tube and out of said mixing tub through at least one said discharge port,
• each said discharge tube having a wall extending between said upper and lower ends thereof and at least one window formed in said wall of each said discharge tube, at least one said window of said outer discharge tube being alignable over at least one said window of said inner discharge tube, at least one among said inner and outer discharge tubes being selectively rotatable relative to said other discharge tube to move said respective alignable windows thereof between at least one aligned position and at least one misaligned position, said windows in said aligned position allowing the flow of cement slurry therethrough from said mixing tub into said inner discharge tube, and said windows in said misaligned position disallowing the flow of cement slurry through said windows.