Casing cementing calculations 7 steps

http://teacheron.com/tutor/dmQF Fluid catalytic cracking-1 link :https://youtu.be/ZpPgw188LOc Petroleum Refining Technology-1 :https://youtu.be/1Wqnv_gH1fQ Drill bits-Roller cone bit https://youtu.be/78RCKSTXGrY Rotary drilling rig components-1 Reservoir simulation-https://youtu.be/JMeDZD5BibE Petroleum Refining Technology-2 https://youtu.be/3RsaQVKZ1GQ CEMENTING PROCEDURE Cement placement procedures In general, there are five steps required to obtain successful cement placement and meet the objectives previously outlined. 1.Analyze the well parameters; define the needs of the well, and then design placement techniques and fluids to meet the needs for the life of the well. Fluid properties, fluid mechanics, and chemistry influence the design used for a well. 2.Calculate fluid (slurry) composition and perform laboratory tests on the fluids designed in Step 1 to see that they meet the needs. 3.Use necessary hardware to implement the design in Step 1; calculate volume of fluids (slurry) to be pumped; and blend, mix, and pump fluids into the annulus. 4.Monitor the treatment in real time; compare with Step 1 and make changes as necessary. 5.Evaluate the results; compare with the design in Step 1 and make changes as necessary for future jobs. Casing and cementing are essential to drilling oil and gas wells. Lining a hole with casing keeps it from caving in after it is drilled, sealing the wellbore from encroaching fluids and gasses. Cementing the casing in place attaches it firmly to the wellbore wall and stabilizes the hole. Preparing the Hole ¾ Preparation of the hole for the cementing jobs starts long before the cementing operation itself. ¾ Before lowering the casing, usually drill pipes have been out of the hole a matter of 12 to 24 hours while surveys and other information were being obtained prior to the decision to set the casing, for example caliper survey of the hole size are run to know the exact dimension of the hole. ¾ Before pumping the slurry, mud circulation appears necessary to clean the hole and to remove cuttings and mud cake attached to the walls. At the same time the casing is worked up or down or rotated during mud circulation. ¾ Sometimes, immediately before putting cement, water added with 5% hexametaphosphate is pumped down the casing to disintegrate the mud cake. Injection Of Slurry ¾ Most bore holes are filled with drilling fluid when the cementing operation begins and for this reason drilling mud is normally used as the displacing fluid. ¾ After the introduction of, the bottom plug, as the cement is pumped inside the casing the pumping pressure steadily decreases. ¾ When the bottom plug reaches the float collar (joint) pressure slightly increases then drop to indicate the rupture of the top plug. ¾ Then, the circulation pressure steadily increases indicating an increasing amount of slurry outside the casing. The arrival of the top plug on the bottom plug results in a sharp increase of the pump pressure. ¾ During the cementing operation, the return mud will flow back into the mud tanks. ¾ The returning mud should be watched carefully. ¾ If mud returns are not obtained at the surface while the cement is being pumped into the casing, then some fluid, either cement or mud is being lost in the formations. ¾ When this occurs, there is always some doubt about the proper placement of cement. Laws of Cementing Calculations Thickening Time ¾ Thickening Time T.T. = Mixing and Pumping Time + Displacement Time + Plug Release Time + Safety Factor ¾ Mixing and Pumping Time ¾ Mixing and Pumping Time = Volume of Cement Slurry / Mixing Rate ¾ Displacement Time = Displacement Volume / displacement rate ¾ Safety Factor = 30 – 60 min. normally used ¾ Surface Time is the time required for the cement slurry to be prepared at the surface and retained for testing. This time is namely small and can be included as part of the mixing time. ¾ Displacement Time: during mixing the cement slurry is pumped inside the casing until the entire dry volume of cement is mixed. This time is dependent on casing capacity and the displacement rate ¾ Number of sacks = Slurry volume / Slurry Yield ¾ Weight of cement = Volume x density ¾ Number of sacks of bentonite = amount of bentonite / 94 ¾ Volume of mix water = No. of Sacks x water required per sack